Wednesday, 8 July 2009

Symmetry Breaking

Symmetry Breaking:
In the early Universe, pressures and temperature prevented the permanent
establishment of elementary particles. Even quarks and leptons were unable to form
stable objects until the Universe had cooled beyond the supergravity phase. If the
fundamental building blocks of Nature (elementary particles) or spacetime itself
were not permanent then what remained the same? The answer is symmetry.

Often symmetry is thought of as a relationship, but in fact it has its own identical
that is preserved during the chaos and flux of the early Universe. Even though
virtual particles are created and destroyed, there is always a symmetry to the
process. For example, for every virtual electron that is formed a virtual positron
(anti-electron) is also formed. There is a time symmetric, mirror-like quality to every
interaction in the early Universe.
Symmetry also leads to conservation laws, and conservation laws limit the possible
interactions between particles. Those imaginary processes that violate conservation
laws are forbidden. So the existence of symmetry provides a source of order to the
early Universe.
Pure symmetry is like a spinning coin. The coin has two states, but while spinning
neither state is determined, and yet both states exist. The coin is in a state of both/or.
When the coin hits the floor the symmetry is broken (its either heads or tails) and
energy is released in the process (the noise the coin makes as it hits the ground).

The effect of symmetry breaking in the early Universe was a series of phase
changes, much like when ice melts to water or water boils to stream. A phase change
is the dramatic change in the internal order of a substance. When ice melts, the
increased heat breaks the bonds in the lattice of water molecules, and the ice no
longer holds its shape.
Phase change in the early Universe occurs at the unification points of fundamental
forces. The decoupling of those forces provides the energy input for phase changes
in the Universe as a whole.

With respect to the Universe, a phase change during symmetry breaking is a point
where the characteristics and the properties of the Universe make a radical shift. At
the supergravity symmetry breaking, the Universe passed from the Planck era of
total chaos to the era of spacetime foam. The energy release was used to create
spacetime. During the GUT symmetry breaking, mass and spacetime separated and
the energy released was used to create particles.

Notice that as symmetry breaks, there is less order, more chaos. The march of
entropy in the Universe apples to the laws of Nature as well as matter. The Universe
at the time of the cosmic singularity was a time of pure symmetry, all the forces had
equal strength, all the matter particles had the same mass (zero), spacetime was the
same everywhere (although all twisted and convolved). As forces decouple, they
lose their symmetry and the Universe becomes more disordered.

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