Ronald Lessik was a scientist working on research of the Unified Field Theory at Martin-Colding Labs.
Dr Colding, seeking to claim all credit for any discoveries, sabotaged a major experiment of Lessik's.
This sabotage caused a major explosion in the lab, killing Lessik's girlfriend and transforming those who worked in the lab.
Lessik's future self had a hand in his discovery of the sabotage, both versions merged after the explosion, and so the seemingly infinitely looping story of The Traveler begins again.