Behind the wormhole is the void, and the void has no concept of time. Regardless how long the three space colonization ships have been lost for, as long as they can finally escape, then to the outside world, from the moment they entered to their escape was only a glimpse.
But what was sent to Jiang Chen's world was only a message, not three space colonization ships from the future.
Based on that fact, Lin Lin only had one hypothesis.
The three space colonization ships have been trapped in the void for eternity, they have become relative to the wormhole outside the universe, the quantum state of the general existence - not alive, nor died.
As to the messages sent, it would be easy to understand sending the technology from the future back.
The purpose was to change the history after World War Two to avoid the Third World War from happening.
