The Stern-Gerlach Experiment (ESI College Physics Film Program 1967)
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- čas přidán 20. 08. 2024
- This film on The Stern-Gerlach Experiment featuring MIT Professor Jerrold R. Zacharias was produced in 1967 as part of the College Physics Film Program by Educational Services, Inc. (ESI), later Education Development Center (EDC), which grew out of the project known as the Physical Science Study Committee (PSSC). Some of the content was developed by the Science Teaching Center (STC), later Education Research Center (ERC), at MIT.
This is a 16mm projection filmed by a digital camera.
This apparatus is currently in hibernation but had been used for a number of decades in MIT's Junior Physics Laboratory while having its parts gradually replaced or upgraded with components like stepper motors.
For you young folks out there (I do hope there are some young people watching this video), think for a moment how the plotting machine works. It uses all Analog electronics, which in the days of the making of this film was a relative breeze since they had the transistor available to them. Now think back to the days of Stern and Gerlach, coils of wire, mirrors and a stopwatch if they were lucky. Those guys really must have had their sh*t together, hey.
Current generation aren't putting that much affect that our ancestors used to ☹️
Engineering student here - ever heard of quantum computing?@@komalsinghgurjar
Same with chemistry. I am constantly amazed from the sheer amount of human ingenuity put into preparations made available without all the fancy equipment. As an amateur, I have no other option than to learn from 50 year-old textbooks and use the obsolete methods, because only these are still available to non-professionals who don't have millions to acquire all the special reagents and machinery...
...the vacume tube(thermoinic tube, flemming tube) was invented in 1904, some time after the phototube was invented, the phototube can be considerd as early versions of (by our standards now primetive) the CCD cell and Field effect transistor(think early mosfet 30cm big), the transistor was invented in 1947, and the 'Stern-Garlach' experiment was constructed by otto in 1921, and conducted by walter in 1922... (Otto Stern and Walter Garlach) ... and actually in comaprison the vacume tubes in 1910 was way faster than the early transistors (basicly the only limmiting factor was how fast the gates could be charged) making tubes that operated at 100Mhz+ easy, (not very practical for their size), and since oscilators circuits was mabe with coils the coil cores was the thing that was actually limiting thier speed... (Thechnically a tube can operate well beyond 20GHz)
...but back i the day the limit was at most a few MHz due to the control problem..
@@Patrik6920 Thanks for the technology and time line info Patrik. I was not trying to be detailed, just to question what may be happening to the human mind as time goes on.
How much more fascinating is analog tech to your brain than digital, there’s something about seeing every piece instead of imagining it
Digital is analogue
Literal nuts and bolts kind of stuff.
Let's see if I'm not completely off.
The temp of caesium gas is 400K, which gives an average speed of √(2RT/M) = √(2·8.315·400/133) = 22.4 10³ cm/s
That gives a flight time within the mag field t = L/ = 12cm/22.4·10³ = 536μs.
The transverse force in the mag field is F = μ gradient(B), therefore the transverse acceleration is μ gradB / m,
and the transverse velocity at the exit of the field is v⟂ = acc × t
The transverse deviation on the screen is then L*v⟂/
The peaks are separated by 3.7mm, so the deviation is half of that: 0.185cm
Therefore v⟂ = 82.9 cm/s
The acceleration = 155 10³ cm/s²
(a posteriori we verify the small parabolic deviation within the mag field is 1/2 acc × t² = 0.022cm, which is negligible)
Finally the magnetic momentum of the caesium atoms is acc×m/grad(B) = 155 10³×(133/6.022 10²³)/10000 = 3.4 10⁻²¹ erg/gauss.
Close enough to the Bohr magneton 9.27 10⁻²¹ erg/gauss?
(all calculations in CGS, because the year is 1967)
Back to the days when introductions were blessedly short and backstories did not exist. Fantastic the way he got into it.
Documenting anything on film in those days wasn't cheap.
Backstories? Similar to propaganda after assassination of President Kennedy?
There is a quality of better understanding when you see things done practicaly .
The "old timers" really knew their stuff. I was very fortunate to have learned from them.
They were the creators or generators, not the robbers of knowledge taken from others.
British Royal Pharmaceutical Society was printing misinformation and personal insults of discoveries of Ludwig Brieger concerning PR3 Methyl Indole (Skatole), as an example, in their 1890s publishings. University of Michigan was starting to transfer knowledge from Berlin about the same time up to 1940s.
My dad's mother is Anna Hahn that fled Germany in 1920s , a few years after my father's father, at age 24 in 1924, from the Brieger family to marry in Milwaukee and live in Detroit where Albert Einstein visited in 1930s-40s when my father was born the day Japanese bomb Pearl Harbor in 1941.
This film reminds me of the atmosphere in which I entered the Philips NatLab (physical research institute) in Eindhoven, the Netherlands, in 1989. We obviously used state-of-the-art equipment from the 1980's, but we also used analogue measurement devices, like box-car and lock-in amplifiers, in order to detect small signals from measurements. And, I clearly remember how my mentor taught me to handle analogue displacement registration, so that I could conduct beam measurements of our laser-diodes by using a potentiometer at the axis of an arm, on which a phototransistor was mounted. I knew these things already from my amateur-background, but applying several techniques like that for professional research, was quite intriguing.
The computer power was furnished by our HP 9000 system, on which we used a Pascal operating system. I used it to calculate the Zernike polynomic coefficients from my measurements of the laser-beams. Furthermore, we used HP small computers with BASIC programs to operate some conditions on the experimental table.
Nowadays, all of this seems from an old world, but we made the best out of it.
Ha. BASIC.
Amazing I don’t understand everything but I find it fascinating.
What a gorgeous demonstration! Sheer physicality of apparatus. Convincing experimental controls so we know what we’re seeing and what we’re not seeing. Modelling of the physics with coils and gyro/magnet gadgets. Transparency about doing the films in two halves filmed in opposite order. And use of CGS units! You could almost feel the excitement Stern and Gerlach must have felt as they watched their detector and saw the unfolding emergence of their original results. Beautiful!
It's fake just like most of the garbage the physics department comes up with. You can see the strings that's moving the magnet. Is it some magical powers of physics? Or is a guy just pulling the string. Remember the simplest answer is usually the right answer.
Fascinating!!! I was born 50 years too late. Love this old stuff that holds true today. Analog and drafting tables for me.
One day, this will become a Television.
You made my day with the demonstration of the precession of the bar magnet on the air bearing, starting at 19:06 and particularly 20:32. This is a fantastic film and I wish I was shown these things when I learned about atomic spin and NMR the first time.
.
I JUST LOVE HOW EVEN COMPLEX EXPERIMENTS OFTEN LOOK
LIKE THEY WERE COBBLED TOGETHER IN SOMEONE'S GARAGE
.
Using a car battery really helped that feel!
Brilliant! Better than any other demonstration/explanation I've ever seen
Thank you for this. I have seen many a slick animated illustrations of the Stern-Gerlach experiment on YT, the real thing is SO much better! I swear i did not blink during the whole 26 minutes of this. Thank YOU!
Quantum physics' strongest warrior
This.
Professor Jerrold R. Zacharias has such a wonderful and casual way of explaining.
This is great presentation. It is amazing what people could do in years past with limited technology.
They were more intelligent. Simple. Peak human kind IQ was in the 1940's-60's. Now it's a decline.
Analog thinking vs todays digital thinking
@@GrandePunto8Vthe real IQ at least technically was late 1800a and early 1900s
@@GrandePunto8Vlow-iq take
@@quantumblur_3145 It is supported by psychometric data from standardised tests.
Best explanation so far. This was fascinating.
Thank you for sharing this amazing video. Its good to see the clever mechanisms and techniques employed back then in action, before the widespread use of electrical automation and detective sensors in our modern era.
For several years I have on and off searched for a replication of the SGE, and finally, hit gold when finding this video! Thank you for posting it.
Wow. This makes me want to design lab experiments and apparatus!
Neat. This is some real deal stuff fight here. A good old film like you'd see in science class. Remember those anyone?
Thank you very much for sharing this video. These are fantastic learning/teaching aids!
Good old, hard science. Thank you for sharing.
I wish my life was back in these days so much. Seems like such a great time to be alive. Nobody has any idea what a social media influencer is, and experiments are all analog and the results get plotted on an etch-a-sketch.
What could be better?
1967: Vietnam war, LSD, Cold war. 1968 even worse with assassinations of RFK & MLK. Mass Protests over Vietnam war, etc. Late 1960s & early 1970s just as chaotic as today.
Having to go to the university library to read about physics lol
@@guytech7310 Yep, those were the times. I think I'd be right at home in a war.
Etch a Sketch. Funny.
Classic old school presentation, watch and learn modern teachers who wish to engage with their pupils.
Never heard of this experiment, but it's old-timey and science so I'll let it surprise me.
One of the top three most important experiments in QM for sure.
Americans that know what millimetres, centimetres and degrees kelvin are in 1967. Refreshing.
this movie was the first time someone decided that zooming and blurring were good things sometimes
Are you aware of how old this clip actually is? And that at the time, this level of quality was state of the art.
There also used to be lots of individuals that would make comments that they themselves thought were funny but actually were simply a good indicator of their stupidity. It was thought that the numbers of these people was steadily decreasing but the internet has demonstrated that any decrease is minimal at best.
;)
poor bert cant look at words without being affected emotionally@@Zerpersande
When Classifying arguments, bert doesn't care about word
order... Except when it matters. 😩
The video was most likely made by running a ciné film beamed by a projector onto a screen with a digital video camera pointing at the image, it looks like it was set to autofocus and was ‘hunting’ for focus, manual focussing on an image attached to the screen before running would have solved that.
What an amazing video. Thank you for sharing !
Very good, there should be more of these videos with other experiments. Why don't they have quality in modern times?
Its easier, I think, to just reference a classic paper, do a few on-screen graphics, maybe invoke a thought experiment or a simulation and move on. Meanwhile, we get further and further away from the actual physics and the original hands-on experiment with all its nuances.
Science has become a religion now. LHC is the modern day equivalent to the Egyptian pyramids with Egyptian priests who spout unintelligible/unrepeatable stuff or stuff so cryptic that only Egyptian priests can understand it. Citizen science is stifled and suppressed as "amateurish" or "irrelevant" since they have not sold their soul to the priesthood. I like this quote from Scott TInker:
"When you remove doubt from science, science becomes a religion". -Scott Tinker
@@uploadJ I would guess it's not unlike Calculus. Once you get past the basics you never bother (need?) to differentiate from first principles again. You work on the assumption that that works so you move on to more complex calculations.
Since this experiment showed in essence that QM correctly described what is going on, there is no need to simply repeat the same experiment. It has already been done, probably many times. And as others have pointed out, a conceptual approach becomes easier to understand.
But I agree, this is an excellent movie, and fascinating to see QM at work!
@@timbeaton5045 Good observation. Calculus certainly need not be re-examined, but, for a purist it may be necessary to go back to see what spurred-on its "discovery" which was the relationship in nature between two or more observations of parameters/variables in nature's functioning.
One sometimes needs to go back and look at why 'guardrails' were put up, like, why is the ground state of Hydrogen assumed to be immutable? I have seen studies to indicate that guardrail may not exist after all.
they do have quality in modern times. they even have high resolution video with colours! stop being such an ignorant moron
Good old, hard science. Thank you for sharing.. Best explanation so far. This was fascinating..
I remember well the PSSC books. Extremely well made for teaching.
Please continue sharing those films, you're doing God's work
WTF does your delusional god have to do with it.
Its always amazing, how much more clear and logical old videos are.
Who calibrated that plotter, 1 sq = 1.35mm, scaled to the source. , good Y range, no clipping. The machine at 1:10 might have been my first view of a TV screen, I think ive felt a desire to create one ever since. and i did make a ring motor with helmolts coils just recently , and videoed it. That machine is so, lets do it 2023. Pulley driven vacuum pump, , diff stack , speed frame angle plate structure, and all the beautiful ones on top, That is an astounding instrument, at any time. Physics is such a beautiful science.
Thanks for sharing this! Great demo
Half way through I understood the point of the experiment and shifted to the right in my seat.
Glad to see in the comments that I'm not the only one gawking at the needle mysteriously going up and down and finding that particular analog-driven invention equally interesting as the cesium atoms ablating somewhere and passing through a split, through a magnetic field and hitting a not further explained detector to make said needle move.
It's just voltages and resistances fed into an amplifier, being driven by natural unseen forces that make meticulously set up matter function like an analog graph maker even more enigmatic in its function until one looks at the graphs and takes a few semesters in College/University to even know which courses to take to learn more about it. Our ancestors gave us the tools we took for granted.
I see that this was a important discovery that lead to the Cesium Atomic clock!
It's wonderful to see that the US had embraced SI units by the 1960s.
No doubt full national metric conversion soon followed?
Only for drugs, guns, and soda.
Americans will be all for it, if you Europeans pay for all the costs to retool & relabel everything. Send us a check for $100B Euros so we can get started!
Yes we did then the corporate types and anti sciences types turned it around back to the dark ages .
@@PsRohrbaughwent back to English stuff for drugs except with law
Metric is for people who count on their fingers.
"All the bugs that always beset every experiment" lol.
Lol, how many weeks did take to "debug" that device?😆
Thank you so much for this video
Very cool! I have not seen this experiment in a long time. To be more exact, I only saw it once in an undergrad experimental physics class and that was almost half a century ago. Having said that, I have done lots of nuclear magnetic resonance as a student, which is kind of equivalent, except that it's being done in the time domain.
The audio is pretty clean despite the video getting pretty dirty at times.
Since the audio on film is read optically, it's surprising that the audio isn't clicking and popping when the video is full of artifacts.
Just everyday home DIY experiments for kids playing in the garage with Dad's Physics gear from work.
great lab experiment
Wonder if this is how Earl Strickland learn to spin a pool ball . . .
Excellent series
A closer look into what cannot be seen with the naked eye.
20:57 this must be the behavior that MRI machines look for when they are imaging
Was für ein schönes Experiment.
Am I just too slow for modern day, or was the pacing a lot better back then?
No,it was better.
I used to have that exact same ion gauge controller.
I own the same model roughing Pump used "Welch 1402"
Really?
purely electromechanical
_badass_
This is amazing thanks ☺️
Thanks so much for the video!
In those days, the video presenters did not ask the audience to like and subscribe by clicking on buttons 😁
Thanks to the detail explanation ❤❤
12:58 Bugs were already a thing in 1967.
The term was even used by Thomas Edison.
mass spectromety principe... awesome...
Well MIT knew how to build stuff back then for sure.
Groovy! Slick! Cool Beans!
I argue that that parallel/anti-parallel dipoles get pulled into "temporal-phase" with the relative "now" moment.
Perpendicular dipoles are shifted temporally out-of-phase with the now moment.
I.e. the magnetic field enforces dipole orientation via selective temporal phases.
Terrific I learn a lot here. 👍
Great hobby !
Was that an HP pen plotter? I used a version made ten years later and found some unfortunate quirks of non linearity.
There is an error in the narration at 25:18: "The oven temperature is about 400 DEGREES [sic] kelvin." The SI unit of temperature called the kelvin is not called a degree.
True, but it sounds ridiculous to most physicists' ears., so we say "degrees Kelvin" if we think the audience doesn't understand. Never a mistake when thigs are clarified.
@@karhukivi So you proudly "defend" ignorance, even maligning other physicists. Dumbing things down doesn't make you smart.
25 minutes on the process of a profound physics experiment and and one of the best explained experiments that's on youtube. And your hung up on degrees kelvin. Congratulations you found a way to dumb it down. You did it!
@@kalidilerious In English the words YOU'RE and YOUR are spelled differently because they mean different things.
Oops
I find it annoying that anything quantum has to be weird, strange or bizarre now. That just sounds like unrealistic expectations. No effort is required to make it interesting. It is what it is, nature.
Second part? Where they study only one side of the split beam? Can’t find the video anywhere online.
I don’t think there can be a conclusion made that spin is “quantum”. The rational given is that the axis or angular momentum will precess in the magnetic field and the angle of that will be based on the orientation when entering the magnetic field. The only issue with this is that the particle is charged. As the particle precesses, it should experience a force. Surely that force will eventually cause the particle to completely align with the magnetic field. This would also explain why measuring spin a second time from a different orientation will have a 50/50 chance of being spin aligned or anti-aligned.
This part is explained in the asymetric field, as explained at 20:00; if you increased the field you wouldnt increase the dieflection of the beam symmetrically, it would favor the stronger field of the two differenty inhomogenous fields, leaning on direction. However it doesnt do this, it either goes all left or all right, showing that there is a type of angular momentum which is being unaccounted for which has two values(two peaks) which is called spin.
If they used a homogenous field where both magnets are the same strength and shape, I think you would have a very good point.
I thought I had an ant or something crawling in and out of my laptops bottom bezel at 2:51
This was an excellent video. They presume we know nothing and walk us through the science.
That's how science was back in 1967.
Today science videos still presume you know nothing, and NEVER will, so they don't even both to do the deep explaining anymore.
they are affraid of childish questions anybody could ask, and they can not answer, that is the reason everything gets obscured nowadays
🎵….Our whole universe was in a hot dense state and nearly 14,000,000,000 years ago….
So how expensive would it be to make magnetically sorted metals, and how could it be used? What metal might yield best quality permanent magnets I wonder...
Could these experiments/demonstrations be used to explain the reasons behind the earths magnetic pole movement?😮
When a list of bureaucracies is considered more important THAN ACTUALLY POSTING THE TOPIC OF THE FILM. This must be important since it looks deliberately buried...
The topic of the film is to show experimental evidence for spin quantization. It's important... if you are a physicist. If not... then why do you care? Mankind has been around for 300,000 years without knowing about it. We did, of course, not have MRI scanners, either, for the longest time. ;-)
Now do that using the dreaded double slit apparatus
could have added a velocity selector fairly easily to sharpen the peaks...??
Cool Vid 😎
19:07 how do you know they are randomly oriented? Theres a big magnet in the middle of the room for the experiment
This would be great if the audio could be cleaned up
Omg they didn't shield the oven...
is this what I missed when i ditched physics in high-school? well now I don't feel so bad about wasting all that time in the bathroom smoking weed...
Need more videos
2:37 Does a compass really point to "North" or "to a South"?
The compass points North, but it points towards a "South" magnetic field. The north pole has a south magnetisation.
@@DeShark88Yes, to clarify, it was designated as the direction the magnet pole is attracted to.
So you need a south magnetic pole on the red side of the compass needle for it to point north.
Full answer: Both.
By convention, the 'red' end a compass needle which points north is actually a "south" pole (since, opposites attract) and vice versa.
The North-seeking pole of a bar magnet or compass needle refers to the geographic direction in which it points. In fact, that pole is attracted to the South magnetic pole of separate magnet as shown in the film. Thdd we Earth’s South magnetic pole is located near (not at) the Earth’s North geographic pole, explaining why the North seeking pole of all bar magnets point north.
18:54 The peaks don't get sharper as you turn up the magnetic field... How on earth could you conclude quantization of spin from this?
21:20 the beam IS spread symmetrically...
Something goofy happened when they turned the b-field higher. It coupled back to the oven.
Interesting. Is this the principle behind mass spectrometry?
Actually, no, but there are similarities. The differences are
1. The atoms in a MS are ionised and are thus moving electric charges. In Stern-Gerlach they are neutral atoms
2. The magnetic field in a MS is uniform and at right angles to the ion stream. Moving electric charge in a magnetic field experiences a force which deflects the ions in a curve to the detector. In Stern-Gerlach, a non-uniform field is used
@@andrewalcock461 Thank you for the prompt response Andrew, that’s very clear and helpful. Very much in keeping with this old movie. Cheers and Best Wishes.
Could somebody explain why the magnetic gyros would lead to a symmetric distribution if normal bar magnets would not? I didn't get it from the video.
Because they are in thermodynamic equilibrium with their environment, which means that we are expecting a classical thermal distribution for the orientations. Imagine a classical pendulum that is randomly exited: the amplitude can take an entire range of values. Here the measurement reveals that individual atomic spins are either parallel or antiparallel to the field gradient, but they can't be "in the middle" for instance. The "deeper" explanation comes from quantum field theory: when the atoms interact with the magnetic field, they can only exchange two kinds of photons with the field, one with left-handed and the other one with right-handed helicity (polarization), i.e. an atom can only flip from one direction to the other, but it can never get to the middle.
They are using magnets to manipulate inside apparatus, electric wires with current to heat the metal and detect the beam - I don't see how this arrangement could cause any interference with the experiment 😉
Now imagine if they could measure this not in 2d but in 3d.
It has been measured in 3d and even 4d. ;-)
What moves the magnet back into the centre after the single coil is switched off?
Gravity is doing its thing throughout, right? And so, when the electromagnetic magnetic force (generated by the electric current in the coil) is switched off, the swing/bar magnet just returns to equilibrium?
EVERYONE COMES FROM THE TESTED TUBES
Are the atoms leaving the oven ionised?
these are the kind of questions
I would expect not for the most part, they were only evaporated iirc
walter gerlach? the one german who had the highest security clearance of all civilians in the third reich gerlach?! wow that is one interesting individual if you are into supressed technology.
Gripping conclusion.
Maybe, someday, in the distant future quantum mechanics will be accepted by the scientific elite.
I have a severe headache.....
Big MRI
Fantasyland vocabulary explains everything, where is mechanical model?
There is no mechanical model for this. This is a purely quantum mechanical effect. ;-)
" over half the atoms in the periodic table are as magnetic as Iron " Who knew that ?
Not I.