Is the human brain an elaborate organic computer? Since the time of the earliest electronic computers, some have imagined that with sufficiently robust memory, processing speed, and programming, a functioning human brain can be replicated in silicon. Others disagree, arguing that central to the workings of the brain are inherently non-computational processes. Do we differ from complex computer algorithms? Are there essential features of the physical make-up and workings of a brain that will prevent us from creating a machine that thinks? And if we should succeed in constructing a computer that claims to be sentient, how would we know if it really is?