Dr Georges Mordreaux was a professor at the University of Makropyrios during the 23rd century. One of his students was Spock. In the 2260s, Dr. Mordreaux conducted experiments in time travel that resulted in the death of the participants.(TOS novel: The Entropy Effect; Star Trek: USS al-Qazwini) He was later seen as the theorist, who made time travel possible.(TOS novel: Time for Yesterday)