Two guys — Stern and Gerlach — did an experiment in 1922. They wanted to measure magnetism caused by electron orbits. At the time, they didn’t know about particles having angular momentum due to spin. So — as explained by [The Science Asylum] in the video below — they clearly showed quantum spin, they just didn’t know it and Physics didn’t catch on for many years.
The experiment was fairly simple. They heated a piece of silver foil to cause atoms to stream out through a tiny pinhole. The choice of silver was because it was a simple material that had a single electron in its outer shell. An external magnet then pulls silver atoms into a different position before it hits some film and that position depends on its magnetic field.
If electrons randomly flew around the nucleus like a cloud, you’d expect a cloudy line on the film. If the electrons had a fixed number of possible electron orbits, the film would show a series of points. In the end, the result was a big surprise — it was neither of the expected patterns. Instead, they got something shaped like the outline of some lips.
They realized that the horizontal deflection occurred even without the magnet, so what looked like two lines were really two points, and that implies that the electrons must be in one of two positions. However, the truth is more complicated.
In fact, Schrödinger’s equations appeared later and shed more light on how the electrons could orbit. It also seemed to imply that the earlier experiment should have been a single spot on the film. The answer turned out to be quantum spin.
According to the video, this was a lucky mistake. The experiment was perfect for measuring quantum spin, but it was unlikely that anyone would have thought to perform it for that purpose. By trying to prove one thing, they had actually proved another thing that no one understood yet. Science is strange and wonderful.
Spin is a big deal in many quantum computers. If you need a refresher on electron orbitals, it is a topic we cover periodically.
silver is magnetic?
Hot, ionized silver is.
I had a discussion with engineers who kept telling me that magnet will separate stainless steel from carbon steel. Even when facing stainless steel knife attracted by magnet they didn’t change mind. The on my research for some easy paper that would explain them they are wrong (I was young and naive) I run opon paper about some british scientist who managed to make copper magnetic. That made me a bot more open minded and in eyes of my fellows engineers less smart.
The facility where I work makes high purity titanium crystals. Ti is obviously not magnetic usually but occasionally we get a few crystals that stick to our magnetic separators. When we’ve analyzed these they are our standard high purity titanium no bulk contamination. It would make an interesting physics thesis to explain this!
Love this stuff. Eat it up like an old XFiles episode.
Y’all understand that electrons are not really spinning…right?
There are recently tons of yt science propagators with a material about just that.
I’m pleased to see we watch almost the same channels.
spin is so simple that it’s astonishing that it is also so meaningless. “surprisingly, electrons can violate pauli exclusion so long as they have opposite spin, which is a binary attribute invented to resolve this conundrum”. it’s just a name for an extra dimension in the electron exclusion vector space. any attempts to get a deeper meaning “are the electrons really spinning?” are fruitless.
with this shaky tool — the dissatisying explanation — they built the entire practice of quantum mechanics. fantastic!
“They heated a piece of silver foil to cause atoms to stream out through a tiny pinhole.” is a confusing sentence.
A diagram of the furnace would be nice, as would an explanation of what part had the pinhole: was it the foil, or the furnace?
The video is set to private? Who made it? Where did it go? Spin a different way?
Science Asylum said in a Youtube community post that they found an “egregious mistake” in it that couldn’t be fixed using the Youtube editor, and they will be uploading a corrected video.
Spin is weirder than you think. It takes two 260 degree turns to go around once.
Much like this gif: https://en.wikipedia.org/wiki/Anti-twister_mechanism
…like USB A connectors.
260 or 360?