This essay plays with potential consequences of time travels into the past. It argues that at least one of the following statements is true: (1) Time travels that modify history are impossible; (2) ... weiterlesentime travels that modify history occur only a finite number of times; (3) the relevant life time of the physical system under consideration is infinite; (4) the system's evolution with time is constrained a priori. This argument exploits the mathematical concept of "random walks", applied to the evolution of a system with time.
Even though written in rather formal style, this piece should not be understood as a work of scientific research or of rigorous philosophy. Rather, it should be read as an exercise in logic -- providing thought-provoking impulses to explore, and discuss, the boundaries of our understanding of the world.