  We discuss a rejectionless global optimization technique which, while being
technically similar to the recently introduced method of Extremal Optimization,
still relies on a physical analogy with a thermalizing system. Our waiting time
method (WTM) is mathematically equivalent to the usual Metropolis algorithm,
but considerably more efficient at low temperatures. The WTM can be used at
constant temperature or it can be combined with annealing techniques. It is
especially well suited for studying the low temperature relaxation of complex
systems as glasses and spin glasses. In the paper we describe the method and
test it on a spin glass example by comparing its performance to Extremal
Optimization.
