Interstellar travel technology. The kind that Ben Rich is talking about in the following excerpt. You may believe or disbelieve in his statements, it your choice and no one else’s.
According to him, civilian scientists are unaware of this tech because Ben Rich and his team never shared the solution to the error in the equations that they found out. Sharing the solution they discovered was not their responsibility but the government’s. However, the government seems to have kept quiet.