Final answer:
Alan Turing is considered the father of theoretical computer science and artificial intelligence. He published a paper that is considered the beginning of modern cryptography.
Step-by-step explanation:
The expert widely considered to be the father of theoretical computer science and artificial intelligence is Alan Turing. In 1949, he published a paper titled 'Communication Theory of Secrecy Systems' which is widely regarded as the beginning of modern cryptography. Shortly thereafter, he co-authored a book called 'Mathematical Theory of Communication' with Warren Weaver.