<human>:  Why is it that a Turing machine can simulate any other Turing machine?
<bot>: Because a Turing machine is a universal machine. A universal machine is a machine that can simulate any other machine. For example, a Turing machine can simulate a Turing machine, a Turing machine can simulate a Turing machine, and so on. This is a consequence of the Church-Turing thesis, which says that any computational task can be performed by a Turing machine.