How would you find lost worlds if we have already discovered almost everything already?

Question: How would you find lost worlds if we have already discovered almost everything already?
- Keywords:
  achievement,
  discovery,
  geography
Asked by to Phillip on 18 Jun 2014. This question was also asked by .
- Phillip Manning answered on 18 Jun 2014:
  
  The world in which we live today is one that we have extensively explored. However, as we go further back in time, we know less and less about life on Earth. This is the closest we will ever get to time-travel, searching our past for clues that help us to reconstruct past or’ lost’ worlds. In many respects, they are not lost, but just waiting to be discovered!

Question: How would you find lost worlds if we have already discovered almost everything already?