We describe the two generic instabilities which arise in quasireversible systems and show that their normal forms are the well-known real Lorenz equations and the Maxwell-Bloch equations. We present for the first time analytic predictions for the appearance of Lorenz chaos and we describe a simple mechanical system which experimentally displays this chaotic behavior.

• Received 23 February 1999

DOI:https://doi.org/10.1103/PhysRevLett.83.3820