|
Word Gems
exploring self-realization, sacred personhood, and full humanity
Quantum Mechanics
|
Stern-Gerlach experiment and
particle spin
|
return to "Quantum Mechanics" main-page
Editor’s note: See more discussion on particle spin in a later article.
from https://quantumatlas.umd.edu/entry/spin/
The Stern-Gerlach Experiment
Originally performed in 1922, the Stern-Gerlach experiment provided scientists with the first hint that quantum particles had an unrecognized kind of magnetism. In the experiment, researchers fired silver atoms through a magnetic field and measured where they landed on a screen. While an ordinary magnet could end up anywhere (depending on its strength and orientation), the atoms only showed up at two discrete spots.
SEE THE VIDEO, a simple explanation of the the Stern-Gerlach experiment
In fact, spin is an intrinsic property of all quantum particles—not just neutrons and electrons. It provides a way to categorize quantum stuff, like how we lump living things together into families and phyla according to their common characteristics. The catch is that non-quantum objects do not have this property—which makes it difficult to find a familiar analog.
Like many things in the quantum world, spin is quantized, which means that the spin of a particle is limited to particular values...
Editor’s note: One physicist explained “quantized spin” like this. A major league baseball pitcher might throw a fast-ball at 81.2 mph; then, another at 80.4; and another at 82.0. In other words, the speed of the ball is all over the map. But when the silver atoms pass through a magnetic field and land on a screen at the back, there are only two “fast pitches,” so to speak; for the atoms, depending on their up or down spin, causing them to land either near the top of the screen or the bottom, with nothing in the middle. This means that the spin, like so many concepts in quantum mechanics, are quantized, issuing is definite, discrete amounts.
|