Interessantes zu Theoretischer Physik

Symmetry in Physics, Spontaneous Symmetry Breaking

Spontaneous Symmetry Breaking (in physics)

Symmetry of a physical system is a feature of the system — observed or intrinsic — that is "pre­served" under change.

For spontaneous symmetry breaking to occur, there must be a system that is symmetric with respect to certain equally likely outcomes. However, if the system is sampled (actually used or interacted with in any way), a specific outcome must occur.


Though the system as a whole is symmetric,

it is never encountered with this symmetry, but only in one specific asymmetric state.


We say: There is a hidden symmetry spontaneously broken in that theory.



In one of her books Lisa Randall says:

Perhaps the best way to explain how symmetry breaking works is to give a few examples:

Almost any symmetry you care to name is not preserved in our world. For example, there are many sym­metries that would be present in empty space, such as rotational or translational invariance, which tell us that all directions and positions are equivalent.

But space is not empty: It is punctuated by stars and planets which occupy particular positions and are so deforming the fabric of spacetime. You see: This is breaking spacetime's symmetry though it remains imp­licit in the physical laws describing spacetime.


Source: pages 205-207 of Lisa Randall's book Warped Passages ...


Wissenswertes zu "Spontaneous Symmetry Breaking, Symmetry in Physics" zusammengestellt durch Gebhard Greiter.
tags: Symmetry1gegreit Spontaneous1gegreit Breaking1gegreit