or there might be humans who were able built ...no one knows. What is the chance of being of living being outta of iron, carbon, oxygen, nitrogen in this planet. From bacteria to the journey of human being who can think critical things now is able to explore out in the universe. The scientist are chasing for aliens if they are there for 15 yrs but still are not able to trace them....Since man has made their journey to moon and now are able to study different astronomical structure, science still doubt about alliens...but technology has been trying track galaxies and find whether there is any other species outside earth or not...if there are none then only humans will rule the universe. From the journey of a cave man to credit card man...evolution has been favoring mankind..there gotta be scientific proof of allien rather than just a Guess saying humans cannot do this n that in todays technology...If people really want to do it..nothing is imposible in this world.