Star Trek: 11 Huge Comparisons Between Deep Space 9 And Babylon 5
4. A Leads To B Which Leads To C Which Leads To A
A causality loop is a type of temporal paradox where event A leads to event B which leads to event C which leads back to event A. Both Deep Space Nine and Babylon 5 feature such a paradox.
In Deep Space Nine, it is revealed that the United Federation of Planets wouldn't exist if Sisko, Dax, and Bashir hadn't accidentally ended up in 21st-century San Francisco during a crucial period in American history. Sisko took the place of a key figure during events leading to the changes that would eventually allow the creation of the United Federation of Planets. If the Federation didn't exist, Sisko wouldn't end up in the past to ensure the crucial events happened.
In Babylon 5, the Minbari ended the Earth-Minbari War after the religious caste examined Jeffrey Sinclair and other pilots and discovered that Minbari souls were being reborn as humans. They also discovered that Sinclair was actually an important leader from their ancient past who had unified their culture. However, Sinclair only became this leader because he eventually traveled back in time during the Shadow War. If he hadn't, Minbari society wouldn't have become the unified federation that launched the Earth-Minbari War.