The Stern-Gerlach Experiment - particles and spin

The Standard model of particle physics models the subatomic matter particles

As quantum waves that have a wave-particle duality

And a quantum spin

In this physics model

A particle of matter is an ordinary particle, that has spin

And that spin is at a continuous constant rate

In this physics model, the elementary strand shaped particle

Is an ordinary three dimensional particle

That moves continuously at a single constant speed, against a static universal reference frame, in three dimensional space

And

The particles of matter are torus shaped particles

Built using the elementary strand shaped particle

With the strand shaped particles inside a particle of matter, moving continuously at a single constant speed

For a particle of matter to move forwards

The particle of matter's perfectly round torus shape has to distort, with the internal strand shaped particles bunching up onto one side or other in the particle of matter's torus ring

The distortion of the particle of matter's tous shape, alters the balance of the particle of matter's internal circular movement

And the particle of matter moves forward

With the plane of the particle of matter's torus ring pointing towards the direction that the particle is moving

In this physics model

A particle of matter can move freely in any direction that is in the plane of its torus ring, by distorting the shape of its torus ring

But not so easily in the directions that are not in the plane of its torus ring

When a particle of matter changes direction to a direction that is not in the plane of its torus ring

Then the particle of matter has to change the plane of its torus ring

To point towards the new direction

Since the inhomogeneous magnetic field of the Stern-Gerlach apparatus changes the beam of electrons from moving horizontally, to moving vertically, i.e. a change in axis

This forces the electrons in the experiment to change the plane of their torus rings to point towards the vertical direction

(In the first version of the experiment, a beam of silver atoms was used rather than a beam of electrons)

In this physics model, on entering the apparatus

The horizontally moving electrons have the plane of their torus rings aligned to a horizontal orientation

But when the electrons are vertically deflected, the vertical deflection forces each electron to align the plane of its torus ring into the vertical plane, with two possibilities

Either the electron's now vertically aligned torus ring

Is spinning 'clockwise'

With respect to the vertical plane

Or the electron's now vertically aligned torus ring

Is spinning 'anticlockwise'

With respect to the vertical plane

As a suggestion, that is how, in this physics model, the inhomogeneous magnetic field in the Stern-Gerlach experiment

Deflects each electron by a 'quantum amount'

Either as a 'quantum amount down'

Or as a 'quantum amount up'

In this physics model, the cause of the electron's behaviour in the Stern-Gerlach experiment

Is the constant speed of the strand shaped particles

That are inside the electron's torus ring

As a note

A suggestion is required as to what a magnetic field is, in this physics model

As a suggestion, perhaps a magnetic field is an overall neutral electric field that, from each atomic point source of the electric field, the majority of the short positive electric field particles move in one direction, and the majority of the short negative electric field particles move in another direction, the two directions being at an angle to each other

The Standard model of particle physics models the subatomic matter particles

As quantum waves that have a wave-particle duality

And a quantum spin

And a copy of an accompanying comment by Ryan Steinbach, explaining why the result of the experiment isn't a case of the magnetic field twisting the orientation of the electron

Totally reasonable point. It turns out that spin is a little more complex than just a magnetic field. It can be better described as "intrinsic angular momentum"

I didn't have the time to get into this in the three minutes, but basically, we know that the orientation doesn't get twisted by the field

Keep in mind, too, that because of the stronger effect of the south magnet, if they were twisting / becoming magnetized by the field, pretty much every electron would go up. Only those facing directly against the field (of which there are likely few or none) would go down. This isn't what we see

That's not to say that measurement doesn't have an effect, just that it's not the effect you're describing

There's a great Looking Glass Universe video that I'll link to here that explains this in better detail

I encourage you to watch it as it addresses your point and helped me clear up some similar confusion!