Its difficult best estimates state there is around 60 billion planets in the goldilocks zone just in the milky way odds are that some will harbour life the number is mind-boggling if we take in the whole universe intact some leading experts state that there are so many potential planets that could harbour life that it is possible that not only could humans exist on other planets but infact there could be planets with exact replicas of oursevelves taking various decisions that would lead to our lives panning out differently kind of like a parrarel earth mind blown