I am afraid the answer I find compelling is a rather trivial one. The two most important inventions in the past two thousand years are the computer and the atomic bomb. The computer will bring about the greatest change to human life since the neolithic revolution, unless the bomb destroys human life altogether.
To arrive at the edge of the world's knowledge, seek out the most complex and sophisticated minds,
put them in a room together, and have them ask each other the questions they are asking themselves.