Firstly I will say it is impossible to disprove anything.
I heard a guesstimation once that the chance of life evolving on an M class planet(earth is m class) is only 1 in 1 billion. I then used this guesstimation and others to do with average planets per star, average star per galaxy, amount of galaxys detected. Then the possibility of there not being life in the universe is 1 in 5 with 35 zeros.
It is only a matter of time before we meet alien life, and taking that it has taken us this long to evolve to our current level, we will meet a balance of younger and older races undoubtably.
Though I don't believe aliens have visited us as they would have undoubtably made themselves know by conquering/exploiting us or bringing us up to there level. I do beilieve in other life.

• closed but poss right - leonard - February 21, 2002 - 03:58 UTC
  • A twist - gcarr - February 21, 2002 - 04:52 UTC
    • Aware - leonard - February 22, 2002 - 07:18 UTC
  • How you can be sure - changlinn - February 21, 2002 - 08:04 UTC
    • Sure - leonard - February 22, 2002 - 07:32 UTC
  • Equation for LIfe in the Cosmos - tripp - March 25, 2002 - 18:47 UTC
    • Equation For LIfe In The Cosmos: 12,500? - cybervox - April 5, 2003 - 23:38 UTC