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Physics, Astronomy & Cosmology / Re: How many spots are produced from Stern-Gerlach apparatus that rotates?
« on: Today at 03:30:38 »
Hi.
Thank you for your opinions @hamdani yusuf .
If the rate of rotation of the SG apparatus was so slow that it didn't change orientation at all, then we just have a standard experiment with static SG apparatus. We have the results for that and we do get two spots, so you would certainly be correct.
I'm not sure which way to approach that discussion. I've written something and edited it for the last hour. I think it may be best to just keep it short.
An electron doesn't have a complete set of spin information. The SG apparatus cannot be a device that acts on the spin because the spin information does not exist. A measurement of the component of spin in the axis aligned with SG apparatus has to be made first.
If a SG device was a simple machine that just twisted the spin of a particle when it passes through, then it ought to do the same thing every time. It doesn't. See your own diagram, last line and focus on the last or right-most SG apparatus. Send in electrons one at a time. They were all the same as far as you can make them (for example, if we assume the SG is a machine to change spins then they have just come out of the previous machine with spin +1/2 in the x-axis and we would reasonably accept that one electron is the same as another electron). The last SG apparatus spits out those electrons sometimes with spin +1/2 and sometimes -1/2 in the z-axis, that is utterly random. The SG isn't following any deterministic rules that a machine acting on the spin should have.
It is far easier to recognise that a measurement of spin in the z-axis was being made. The randomness of the final result or output from the SG is then adequately explained because the wave function collapse was inherently random.
Once the appropriate component of spin is known, the SG apparatus does nothing at all to change that. The electron is attracted or repelled to/from the North pole but that is a change in trajectory and not in the spin. At no point along the SG apparatus is the spin made more, less or twisted in direction. The only important event for the final spin result was right at the start (where we would assume a measurement was made).
Best Wishes.
Thank you for your opinions @hamdani yusuf .
If the divergence is strong enough, and the rate of change of the axis is slow enough, then the final result is two dots along the axis at the end of the SG apparatus.I'm not sure what you meant by "slow enough" change of the axis.
If the rate of rotation of the SG apparatus was so slow that it didn't change orientation at all, then we just have a standard experiment with static SG apparatus. We have the results for that and we do get two spots, so you would certainly be correct.
The results can be explained by assuming that the passing through SG apparatus changes the orientation of the atoms spin. Just like how polarizers change the polarization axis of the passing light.Sorry, no, it isn't simple to assume the SG actively changes the spin. Polarising filters and polarised light can also have similar problems.
I'm not sure which way to approach that discussion. I've written something and edited it for the last hour. I think it may be best to just keep it short.
An electron doesn't have a complete set of spin information. The SG apparatus cannot be a device that acts on the spin because the spin information does not exist. A measurement of the component of spin in the axis aligned with SG apparatus has to be made first.
If a SG device was a simple machine that just twisted the spin of a particle when it passes through, then it ought to do the same thing every time. It doesn't. See your own diagram, last line and focus on the last or right-most SG apparatus. Send in electrons one at a time. They were all the same as far as you can make them (for example, if we assume the SG is a machine to change spins then they have just come out of the previous machine with spin +1/2 in the x-axis and we would reasonably accept that one electron is the same as another electron). The last SG apparatus spits out those electrons sometimes with spin +1/2 and sometimes -1/2 in the z-axis, that is utterly random. The SG isn't following any deterministic rules that a machine acting on the spin should have.
It is far easier to recognise that a measurement of spin in the z-axis was being made. The randomness of the final result or output from the SG is then adequately explained because the wave function collapse was inherently random.
Once the appropriate component of spin is known, the SG apparatus does nothing at all to change that. The electron is attracted or repelled to/from the North pole but that is a change in trajectory and not in the spin. At no point along the SG apparatus is the spin made more, less or twisted in direction. The only important event for the final spin result was right at the start (where we would assume a measurement was made).
Best Wishes.