The magical creation of the photon.

[Erasmus00]

I need some help. I want someone to help explain the Stern-Gerlack experiment using the standard model.

 

I was half way through typing up an explanation when I discovered the wiki article on the experiment is rather good. Check it out.

 

If you have any questions, I'm happy to answer.

-Will

[Little Bang]

I am aware of the current explanation of Stern-Gerlack in fact I ran across a description of it about the time I joined Hypography. it was just a description of the results of the experiment and the sole reason that started me on the path of deserting the standard model. It will take me a couple of days to write my rebuttal to the current explanation.

[Little Bang]

I have decided to go ahead and post this preliminary statement because I am sure that it will create a very heated argument.

 

Imagine if you well a 12 inch length of hose. Lay it on a table with its length pointed away from your body. Now place one of your hands on the hose and roll it to your left. I will call this motion left hand spin. With the hose maintaining this left hand spin we glue the two ends of the hose together producing a torus with the above mentioned left hand spin. I will call this configuration an electron. The opposite configuration would of course be the anti-electron. If I hold the electron torus up in front of my face looking at the torus edge on then an astute observer would say, " Wait, if I flip the torus around then it will have right hand spin ". The observer would be absolutely correct. The electron can have both a positive or negative charge depending on the frame of reference of the observer. If that is true how does the electron torus and the proton torus interact? The electron torus and the proton torus will act like two bar magnets, where the north and south pole will always lineup ( left hand spin will lineup with right hand spin). One thing I want to interject here is that the diameter of the proton torus is extremely small compared the electron torus because the creation wave length of the proton is over a thousand times shorter than the creation wave length of the electron

 

I would think if the above idea is correct then an electron stripped from the nucleus of an atom as part of an electron beam would have no orientation meaning that half the electrons in the beam would appear negative and the other half would appear positive at any given instant. Passing the beam between the north south poles of a magnet would split the beam in two. Passing one of the split beams through another magnet would produce the same result.

[Erasmus00]

I would think if the above idea is correct then an electron stripped from the nucleus of an atom as part of an electron beam would have no orientation meaning that half the electrons in the beam would appear negative and the other half would appear positive at any given instant. Passing the beam between the north south poles of a magnet would split the beam in two. Passing one of the split beams through another magnet would produce the same result.

 

If you don't change the orientation of the magnetic fields, then the beam will only split the first time. After that first split, running either of the two beams through the same orientation apparatus again will NOT result in a split.

-Will

[Little Bang]

Your logic eludes me. If the electrons in the first beam have nothing but random orientation then the electrons in the second beam would also have nothing but random orientation.

[Erasmus00]

Your logic eludes me. If the electrons in the first beam have nothing but random orientation then the electrons in the second beam would also have nothing but random orientation.

 

It's not really a question of logic, simply the results of the experiment. If you start with an unpolarized beam (random spin orientation), and run it through an experiment with (lets say) a north/south orientation you get two beams.

 

If you run either of these beams through ANOTHER north/south oriented beam it will not split again. We say these beams are polarized.

 

However, if you take one of these beams and run it through an experiment with an East/West orientation the beam WILL split into two more beams.

 

If you take one of these East/West split beams, and run it back through another North/South detector it WILL split again.

 

Quantum mechanics explains this with the uncertainty relation between different components of angular momentum.

-Will

[Little Bang]

IF my post in 139 is true then my statement in 141 is also true. One of us does not understand the experiment and I'll bet my ace it is not me.

[Erasmus00]

IF my post in 139 is true then my statement in 141 is also true. One of us does not understand the experiment and I'll bet my ace it is not me.

 

One of us has done a version of this experiment. It is also very similar to light polarizers, which might be more intuitive since there is a ready classical system at hand (i.e. light as a wave). I think the quantum book by French, while lacking in a lot of places, has a discussion of sending light through polarizers.

 

Think of splitting the beam as dividing it into two polarized beams.

-Will

[Little Bang]

Will, I spoke in the heat of the moment so I owe you an apology. You are of course right so I'm going to try and come up with another explanation.

[Little Bang]

Ok, I have envisioned a way that the torus idea can work with Stern-Gerlack but first I need some help. If the electron is a charged particle why do they come off the cathode as a beam? Why wouldn't they just spread apart like a shotgun blast?

[modest]

Ok, I have envisioned a way that the torus idea can work with Stern-Gerlack but first I need some help. If the electron is a charged particle why do they come off the cathode as a beam? Why wouldn't they just spread apart like a shotgun blast?

 

There is a direction involved from the cathode to the anode. As I understand things, the cathode is heated up allowing for free electrons. There is then a voltage difference between the cathode and anode accelerating the electrons. Consider your monitor in front of you (if it isn't a flat panel). The cathode is further away from you than the anode.

 

You may be wondering why electrons don't hit the anode and get absorbed by it. In fact, some do, but there is a hole in the anode through which the beam is emitted. It's a small hole, so the beam isn't like a shotgun blast as you say. But, neither is it a perfect beam. It does spread out a bit.

 

~modest

[Little Bang]

Maybe I didn't explain my question well enough. I understand how it works ,the electrons emitted from the cathode impact the phosphor molecule on the anode exciting the molecule causing it to emit visible light. If there are no guide magnets on the cathode then the electron beam produces a small dot in the center of the screen. One would think that the force of repulsion between individual electrons would spread the electrons all over the screen. So what keeps the beam together in order to make that single dot.

[modest]

Maybe I didn't explain my question well enough.

 

You did, I just did a terrible job interpreting it. :doh:

 

I understand how it works ,the electrons emitted from the cathode impact the phosphor molecule on the anode exciting the molecule causing it to emit visible light. If there are no guide magnets on the cathode then the electron beam produces a small dot in the center of the screen. One would think that the force of repulsion between individual electrons would spread the electrons all over the screen. So what keeps the beam together in order to make that single dot.

 

It's a good question and, honestly, I don't know. I would think there is some scattering in the beam - I don't see why they wouldn't be exchanging virtual photons and subject to the coulomb force. Will?

 

~modest

[Erasmus00]

It's a good question and, honestly, I don't know. I would think there is some scattering in the beam - I don't see why they wouldn't be exchanging virtual photons and subject to the coulomb force. Will?

 

There is scattering and repulsion in the beam- in most particle experiments magnetic fields are used to focus the beams to avoid this problem.

 

In shorter experiments, the scattering perpendicular to the beam isn't as noticeable because the electrons are moving at nearly the speed of light along the beam so the longitudinal momentum is much, much greater then the transverse momentum that is developed from the repulsion of the electrons.

 

In the Stern-Gerlach experiments, to avoid this, typically neutral atoms with non-zero magnetic moments are used.

-Will

[Little Bang]

The velocity of the electron is totally dependent upon the potential of the anode. There is of course a minimum potential in which the electron will jump the gap between the anode and cathode but even that velocity is very high so you are right the electron is traveling so fast that they don't have time to spread apart. Does this information preclude the possibility that some force may tend to hold the beam together? What is the widest gap that we can get electrons to jump to the anode?

[Erasmus00]

Does this information preclude the possibility that some force may tend to hold the beam together?

 

Not conclusively, but we can precisely measure the forces between two electrons and only ever find electric and magnetic forces.

 

What is the widest gap that we can get electrons to jump to the anode?

 

I don't understand the question.

-Will

[Little Bang]

Example, I doubt seriously that a potential difference could ever be large enough to start an electron beam between say Alpha Centauri and Earth but suppose we could and passed that beam through a splitter would the beam still be polarized when it reached Alpha Centauri?