更改

* 考虑一个围绕某个竖直的直径旋转的圆形箍上的珠子。当旋转速度从静止逐渐增加时，珠子最初会停留在环底部的初始平衡点(直观上稳定，重力势最低)。在一定的临界旋转速度下，这一点将变得不稳定，珠子将跳到另外两个新创建的离中心等距离的平衡点中的一个。起初，系统相对直径是对称的，但在通过临界速度后，珠子最终停留在两个新的平衡点中的一个，从而打破了对称性。

* 考虑一个围绕某个竖直的直径旋转的圆形箍上的珠子。当旋转速度从静止逐渐增加时，珠子最初会停留在环底部的初始平衡点(直观上稳定，重力势最低)。在一定的临界旋转速度下，这一点将变得不稳定，珠子将跳到另外两个新创建的离中心等距离的平衡点中的一个。起初，系统相对直径是对称的，但在通过临界速度后，珠子最终停留在两个新的平衡点中的一个，从而打破了对称性。

==Spontaneous symmetry breaking in physics==

==Spontaneous symmetry breaking in physics 物理学中的自发对称性破缺==

[[File:Spontaneous symmetry breaking (explanatory diagram).png|thumb|right|250px|''Spontaneous symmetry breaking illustrated'': At high energy levels (''left''), the ball settles in the center, and the result is symmetric. At lower energy levels (''right''), the overall "rules" remain symmetric, but the symmetric  "[[sombrero|Sombrero]]" enforces an asymmetric outcome, since eventually the ball must rest at some random spot on the bottom, "spontaneously", and not all others.|链接=Special:FilePath/Spontaneous_symmetry_breaking_(explanatory_diagram).png]]

[[File:Spontaneous symmetry breaking (explanatory diagram).png|thumb|right|250px|''Spontaneous symmetry breaking illustrated'': At high energy levels (''left''), the ball settles in the center, and the result is symmetric. At lower energy levels (''right''), the overall "rules" remain symmetric, but the symmetric  "[[sombrero|Sombrero]]" enforces an asymmetric outcome, since eventually the ball must rest at some random spot on the bottom, "spontaneously", and not all others.|链接=Special:FilePath/Spontaneous_symmetry_breaking_(explanatory_diagram).png]]

===Particle physics===

===Particle physics 粒子物理===

In [[particle physics]], the [[force carrier]] particles are normally specified by field equations with [[gauge symmetry]]; their equations predict that certain measurements will be the same at any point in the field. For instance, field equations might predict that the mass of two quarks is constant. Solving the equations to find the mass of each quark might give two solutions. In one solution, quark A is heavier than quark B. In the second solution, quark B is heavier than quark A ''by the same amount''. The symmetry of the equations is not reflected by the individual solutions, but it is reflected by the range of solutions.

In [[particle physics]], the [[force carrier]] particles are normally specified by field equations with [[gauge symmetry]]; their equations predict that certain measurements will be the same at any point in the field. For instance, field equations might predict that the mass of two quarks is constant. Solving the equations to find the mass of each quark might give two solutions. In one solution, quark A is heavier than quark B. In the second solution, quark B is heavier than quark A ''by the same amount''. The symmetry of the equations is not reflected by the individual solutions, but it is reflected by the range of solutions.

An actual measurement reflects only one solution, representing a breakdown in the symmetry of the underlying theory. "Hidden" is a better term than "broken", because the symmetry is always there in these equations. This phenomenon is called [[Spontaneous magnetization|''spontaneous'']] symmetry breaking (SSB) because ''nothing'' (that we know of) breaks the symmetry in the equations.<ref name="Weinberg2011">{{cite book|author=Steven Weinberg|title=Dreams of a Final Theory: The Scientist's Search for the Ultimate Laws of Nature|url=https://books.google.com/books?id=Rsg3PE_9_ccC|date=20 April 2011|publisher=Knopf Doubleday Publishing Group|isbn=978-0-307-78786-6}}</ref>{{rp|194–195}}

An actual measurement reflects only one solution, representing a breakdown in the symmetry of the underlying theory. "Hidden" is a better term than "broken", because the symmetry is always there in these equations. This phenomenon is called [[Spontaneous magnetization|''spontaneous'']] symmetry breaking (SSB) because ''nothing'' (that we know of) breaks the symmetry in the equations.<ref name="Weinberg2011">{{cite book|author=Steven Weinberg|title=Dreams of a Final Theory: The Scientist's Search for the Ultimate Laws of Nature|url=https://books.google.com/books?id=Rsg3PE_9_ccC|date=20 April 2011|publisher=Knopf Doubleday Publishing Group|isbn=978-0-307-78786-6}}</ref>{{rp|194–195}}

====Chiral symmetry====

====Chiral symmetry====