Signal Based Time Travel

Essentially firing a laser into the past, or some other barely disruptive signal that minimizes the amount of change introduced into history, but still generates more instances of time travel duplication of the universe. Capable of producing Parallel Sets Of Timelines. Essentially all time travelers of a certain sophistication and above became involved in producing Parallel Sets Of Timelines using Signal Based Time Travel, both sets of times that they controlled, and sets of times other time travelers had created, so that they could learn their characteristics and methods to exploit them. Discovery of one time can therefore quickly lead to the discovery of an entire set of associated, duplicated times.

See: The First True-Screwed Loop 

See: The Second True-Screwed Loop