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* 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。
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==Spontaneous symmetry breaking in physics==
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==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]]
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===Particle physics===
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===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.
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在粒子物理学中,载力子通常由规范对称的场方程表示;它们的方程预测到某些测量值在场的任何点上都是相同的。例如,场方程可以预测两个夸克的质量是常数。通过求解方程来求每个夸克的质量可能会得到两个解。在一个解中,夸克A比夸克B重;在第二个解中,夸克B比夸克A重相同的量。方程的对称性不是由单个解来反映的,而是由解的范围来反映的。
    
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}}
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一个实际的测量只反映了一个解,代表了其潜在理论的对称性的破缺。在这里“隐藏”是比“破坏”更好的术语,因为对称性总是存在于这些方程中。这种现象被称为自发对称破缺(SSB),因为(我们所知道的)没有任何东西会打破方程中的对称性。
    
====Chiral symmetry====
 
====Chiral symmetry====
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