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> I don't understand how crystals break spatial symmetry. Imagine doing some experiment in a vacuum. It will work the same no matter which direction you orient
by pdonis 4y ago
> I don't understand how crystals break spatial symmetry.
Imagine doing some experiment in a vacuum. It will work the same no matter which direction you orient the experiment or where in space you put it.
Now imagine doing the same experiment inside a crystal. Now it won't work the same no matter which direction you orient the experiment (because some directions will cause something in the experiment to hit one of the atoms of the crystal, and other directions won't) or where in space you put it (because there are crystal atoms in some places but not in others).
That's how the crystal breaks spatial symmetry.
- raattgift 4y agoA minor addition to clarify: if one did the same experiment inside an ideal gas, rather than a crystal, there are still atoms in the way (compared to vacuum) but there is no preferred direction through the atoms. Crystalline structure gives a preferred direction along the principal axes. This might mean there is less optical extinction along the principal axes from deep inside the crystal, for example, whereas from deep inside the ideal gas optical extinction is the same in every direction. That is, the view varies depending on direction one looks within a crystal. "Symmetrical" means that the view should not vary that way. If we freeze our gas into a crystal lattice, we break this symmetry.