From the point of view of (a) chemical evolution and (b) exobiology (the origin of life in the universe), we discuss the possibility that phase transitions of the type postulated by Salam in 1991 to occur in a racemic mixture of amino acids, may play instead the role of an amplification mechanism in the novel context of chirally-pure samples of amino acids. Salam's seminal contribution referred to the role of phase transitions in the induction of the observed homochirality of protein amino acids. This was assumed to occur in a racemic mixture that, as a consequence of the conjectured phase transition, turned homochiral beneath a certain critical temperature, T_c. In the present review we discuss selected theoretical aspects of the question of homochirality. The relevance of starting a new generation of experiments is pointed out, as suggested by the present author in 1991. These experiments should test a form of condensed matter that has so far not been at the forefront of research from the point of view of the phase transitions. We discuss those aspects of the origin of homochirality which are still valid and require verification
