## 5aPA8. Thermoacoustic onset as a critical transition.

### Session: Friday Morning, December 6

### Time: 10:20

**Author: Eric Smith**

**Location: Appl. Res. Labs., Univ. of Texas, Austin, TX 78713-8029**

**Abstract:**

It is noted that the processes of phase transition in equilibrium
statistical mechanics and onset in thermoacoustic engines have the same
mathematical features, and arise in the same way from the trace over a
statistical density matrix. Onset differs physically in being a process of
spontaneous breaking of time-translation symmetry, while equilibrium critical
systems are by definition time independent. Heat engines thus represent a class
of systems through which the concept of phase transition may be extended to
include a limited range of classical dynamics.

ASA 132nd meeting - Hawaii, December 1996