One theory is that if they can time travel backward, we don't observe them because within seconds of being created they keep plunging back to the first few mins of the universe, getting lost again in its primordial chaos.
the reason why we cannot see the edge of universe can be that the time in which the the light from that distance reaches us the universe has expanded more than that.
https://www.msn.com/en-us/news/technology/the-universe-may-be-dominated-by-particles-that-break-causality-and-move-faster-than-light-new-paper-suggests/ar-BB1lOqI4?ocid=winp2fptaskbar&cvid=9613b9d9f0234a7da1fcca6bd5ca388c&ei=20&sc=shoreline