3. Wave Mechanics (continued) and Stern-Gerlach Experiment

MIT 8.05 Quantum Physics II, Fall 2013
Instructor: Barton Zwiebach

In this lecture, the professor talked about position and momentum in quantum mechanics, Stern-Gerlach Experiment, etc.

License: Creative Commons BY-NC-SA

[yacc]

57:00 point particle. THE MOST IMPORTANT FRAGMENT about "classical image"

[RicardoQuispeM]

Thanks MIT for this class <3
Greetings from Peru

[Masporquena]

40:00 - Here starts the explanation about Stern-Gerlach experiment

[BaBaBoi-DoYouKnowTheWay]

Very good explanation and flow. Thank you MIT and Sir.

[youcanknowanything]

Just 😂 realized that there are transcripts of the entire lecture in the show notes. Very very helpful for us newbies👍👍😎

[delmercerroncrisostomo]

Un orgullo para mi, ver a un peruano enseñando en la universidad mas prestigiosa del mundo.

[zphuo]

@1:03:20 force goes in the direction that makes u.B grow the fastest. That is what gradient means.

[yeechi]

I yell wow several times during this lecture, Thank you sir.

[yacc]

58:36 IMPORTANT: for the proton, 58:53 neutron, these are "clues" that are "composite"

[yacc]

1:15:34 spin states, bases and superpositions 1:13:00. 1:13:32

[岡安一壽]

I think that an electron has shift in coordinate (1/2π)msλ in r-direction. [ms: spin quantum number, λ: wave length] Accordingly, the angular momentum is as follows: (De Broglie equation: p=h/λ)
And the magnetic moment is as follows:
(area)･(electric (q/2m)L+2(q/2m)S.
Thus, we can know that the g-factor for spin angular momentum is equal to 2.
I'm sorry that I'm not good at English.

[ckkwok]

Very nice teacher, he teaches word by word.

[elnorteno]

UNI is proud of you Barton, String Theory ace.

[MUHAMMADNazar-ik]

Thank you so much for this nice lecture ❤ you are really a nice teacher ☺️

[edwardmacnab]

It is my understanding that in a sequential experiment you indeed get two results from one beam. So which is it, because this is crucial information.you are first to explain inhomogenous. tysm.

[willyou]

g for the electron is not actually exactly 2, i think it would've been a better idea to state that and actually say g ispredicted and have been measured to be 2.00231930436182

The simplest approximation one can give for that is 2(1+2pi/a) where a is the fine structure constant

[charleslafcharis]

I have spent twenty years researching Stern-Gerlach experimental outcomes and their association to electron spin. It is based on a new concept of Magnetic Polarity and Magnetism which transforms an atom from a hypothetical structural configuration, to a real and actual physical entity that accurately depicts each and every known property associated with atomic orbital structure; such as shells, energy subshells, electron spin, quantized energy states, orbital priority, orbital configuration, hybridization, magic number elements, electronegativity, atomic bonding, and much more. Admittedly; it may be claimed that these "SLA" Theories simply confirm existing known features of atomic structure; but they do so based on scientific reasoning which predict, not only the distinct characteristics of an atom, but also the properties associated with those characteristics. In other words; the "SLA" Theories explain how and why these characteristics exist.

Proof comes in the form of Stern-Gerlach experimental outcomes! In that these unique theoretical concepts actually predict each of the inconceivable Stern-Gerlach experimental outcomes; thereby proving that spin can alternate between opposite states, and that these states are indeed quantised. In other words; the research which is soon to be accessible on a website, and published in coming weeks, is in total agreement with the Stern-Gerlach experimental outcomes.

These so called "SLA" Theories are basically a rule book that justify each and every known feature of an atom. But when that rule book, accurately predicts, not only the Stern-Gerlach experimental outcomes; but also predicts the numbers of isotopes of each element of the Periodic Table; then it is time to take notice; for this does not fall within the realm of existing scientific reasoning. This is a world first; which does not only predict numbers of isotopes, but explains why they come to exist.

The research is quite extensive, encompassing 194 pages of notes, incorporating over 62, 000 words, and many illustrations; having taken over twenty years to compile. The findings are far too lengthy to contemplate even a concise entry in a comment section of Youtube. I sincerely believe that science will accept my findings in their entirety, for they are near enough to perfect; and there are far too many revelations on many fronts (Magnetism, Atomic Structure, and Stern-Gerlach experimental outcomes), for it to be a coincidence.

[aussiedog]

I bought Dr Zwieback's new book on QM. Very good.

[annamitchell]

Thanks. Would've failed my project without this video

[whatitmeans]

If every Ag atom have a magnetic random oriented magnetic moment (as a classical magnet), when entering the SG experiment they will be reoriented by the magnets with 50% chance up or down just because they starts randomly oriented, and then flying through the SG experiment it will be deflected up or down given this new reorientation. Then if another SG experiment is introduced for just one of the outputs in the same orientation than the first one, since incoming Ag atoms are all up or down oriented they will have only one output.
Now, if the second SG experiment is aligned in a perpendicular direction, again is the same effect that starting with random Ag oriented atoms because just for slightly small differences they will be splited in one or another orientation with 50% chance.
With this, considering that I am just throwing classical magnets the results have no mistery in a classical point of view.
So I don't understand why they starts with the confussing Spin explanation, when actually it is not required (it could be another explanation too, given that the experiment have completely logical results from a classical viewpoint).
And it is the quantum Spin model what introduces all the counterintuitive phenomenas in the SG experiment explanations.

So my question is, ¿why is never considered that the Ag atoms reoriented themselves when facing the SG experiment magnets?? Surely must have an explanation, smart people doing quantum surely have think about this before.

So, if I replicate the SG experiment in ^z direction and then blocking one of the outputs, and then I place another SG experiment, but sligthly oriented like (75°^z + 15°^x) direction... ¿the output will be again a 50% chance split in +/- 1/2 spin direction?¿or it will have a much bigger concentration in the ^z direction as if Ag atoms are just classical dipole magnets??