Spontaneous symmetry breaking facts for kids

Spontaneous symmetry breaking is a way symmetry breaks in a physical system. The underlying laws do not change, but the system as a whole changes. Symmetry breaking in physics occurs when a system is crossing a critical point. Small fluctuations decide the system's fate, by determining which branch is taken.

Uses for spontaneous symmetry breaking

Spontaneous symmetry breaking can create a particle called a Higgs boson. This is a particle which is the force transferring particle (boson) of the Higgs field. The Higgs field gives mass to fundamental particles such as electrons. Also, many scientists believe in the Higgs effect (which is very similar to spontaneous symmetry breaking) to answer questions that are not answered in the standard model of physics. The standard model predicts that certain types of quarks should have a mass of zero, while in reality they have a non-zero mass value. Some scientists believe that spontaneous symmetry breaking is the answer.

Method of spontaneous symmetry breaking

For spontaneous symmetry breaking to happen, you need an environment which is completely symmetrical, and has at least two outcomes that are equally likely. Spontaneous symmetry breaking starts with two particles that are completely equal; their spin is equal, too. Mathematically, spontaneous symmetry breaking can be extremely puzzling, since you start out with two identical things and end up with two non-identical things. However, in practice, it is not so puzzling. If you have two particles moving at each other with equal speed, it would seem impossible for either of them to do anything but be symmetrical. However, if each particle has an equal 50-50 chance to be spinning one way or another, it is possible–in theory and in practice–to have this symmetry broken. It begins with symmetry to start with because the particles have an equal and symmetrical 50-50 chance of spinning one way or another.

Images for kids

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  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" enforces an asymmetric outcome, since eventually the ball must rest at some random spot on the bottom, "spontaneously", and not all others.

See also

In Spanish: Ruptura espontánea de simetría para niños