Gene

Quantum mechanics

Theoretical physics

Transition (genetics)

Phase (matter)

Phase transition

Astrophysics

Biochemistry

Physics

Chemistry

Universe

Physics Reports

I discuss the reasons for believing that phase transitions occurred in the very early history of the universe, and the topological structures that may have been generated thereby-in particular, the strings and monopoles. The aim is mainly pedagogical, with special emphasis on unsolved problems.

Some implications of a cosmological phase transition