This Experiment Proved Quantum Mechanics

The Stern-Gerlach Experiment was the breakthrough that showed us the world of quantum physics. Einstein called it ‘the most interesting achievement’... but you’ve probably never heard of it…

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Chapters:
00:00 A Brief History Of Physics
01:46 Understanding The Atom
03:33 Bohr's Atomic Model
05:06 Ad Read
06:28 The Stern–Gerlach Experiment
09:06 How The Experiment Nearly Failed
11:07 The Breakthrough That Changed Physics Forever
12:33 The Twist In The Story

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[JrgenMonkerud-golg]

And btw, no the experiment doesn't really tell you spin is discreet at all, it tells you that in sucb a magnetic field spin aligns or anti aligns with the magnetic field, thats it pretty much. Thats not the same thing as fundamental discreetness. It is easy to come up with a classical model of a magnetic moment acting like this.

[RGF]

I remember the Stern-Gerlach experiment being presented in my undergrad QM and Atomic Physics courses as the experiment that verified electron spin. Thanks for the real “back story”. Interesting how when one sets out to prove or disprove something, the results turn out to verify something different.

[n-da-bunka]

Thanks for the "new" presentation of this scenario. I learned about the second-hand cigar smoke being a KEY to the success of this experiment but did not realize that it wasn't originally designed to identify spin.

[drbonesshow]

I'll give this guy credit he smoothly introduced his sponsor into the discussion. I'm a physics professor, I appreciate skillfulness even when it involves advertising. Better than the getting hit in the puss with a pie approach. Blueberry is my favorite.

[OpieJohansen]

Didn't hear a word of Dr. Miles for the first two minutes because I was waiting for the two pictures on the wall behind him to move on their own again!

[philipsamways]

A great video, and sensibly humorous loved the " not a brothel" sign behind him when drinking his coffee. Master stroke

[waltertoki]

This explanation on Bohr’s model missed a key part. Bohr used Planck’s constant h, that was used to explain Black Body radiation, in his model of the Hydrogen spectrum. This constant h divided by 2pi is the quantum unit of angular momentum that the electron can have when it orbits the nucleus. This was a revolutionary step in modern physics.

[davidwright]

Stern-Gerlach experiment is hardly forgotten; it’s covered in every QM class. Also, it was nowhere near first experiment to show quantum effects: blackbody radiation, hydrogen spectrum, etc. came first.

[Finkelthusiast]

I've heard abou this experiment for years and I am so glad to hear the story of the hurdles and insights that we needed to attain the result. Great video!

[ytashu]

Stern-Gerlach experiment is not forgotten, if mere amatures like myself, born long after that era, have some (small) understanding of it. Gotta say the last point you made about what they thought they were measuring vs what they actually measured, was something i hadn't really appreciated. Thanks for telling the tale in a fun and engaging way!

[cyrilio]

OMG, seeing people smoke cigars while doing lab work is so crazy.

[bhut]

I recall being lectured about the Stern-Gerlach Exp during 1st year, in the late 60's. Thanks, from a stern geezer. This was well presented but definitely not a "forgotten experiment."

[karankakkar]

Literally all quantum textbooks start with explaining the significance of these experiments

[burrahobbithalf]

Forgotten? All physics majors know the Stern-Gerlach experiment. What they don't know is that Stern didn't expect to see quantized angular momentum.

[DrDeuteron]

they were also lucky that a 19th C mathematician named Sophus Lie worked an useless abstract realm that turned out to be not so useless, otherwise this two component spin thing would have never made any sense.

[theophrastus.]

I got married. After that, I knew the reality around me was fundamentally different from what I thought I understood.

[shantanusapru]

So how *did* other scientists discover that they were wrong, and that what the two had discovered was actually electron spin?
Maybe make a video on/explaining that?!! That'd be cool!

[harrybarrow]

This is a really good video.
My first degree is in physics and maths, and I remember learning about the Stern-Gerlach experiment 60 years ago.
Nevertheless you really held my attention and I learned about the personalities involved in determining the physics,
Although it is almost 4 am, you kept me interested. 🙂

[johnpayne]

Nicely done
Once again a triumph of the saying: “I was right but for the wrong reason”

[christophas]

Sorry for being that guy, but you've some errors in the introduction. First, Stern was German and Breslau a German city back then. That changed in 1945.
Secondly, the 19th century refers to 1801 till 1900. 1901 till 2000 is 20th century.