On the Fermi paradox debate. Seems to me, we don't see intelligent aliens because there aren't any nearby and also near our level of sophistication.<br><br>Assumptions:<br><br>1) As life progresses technologically it either destroys itself (nukes, nano-tech gone wrong), or it becomes super intelligent and departs this universe (or continues to exist just as energy, or whatever else we can't explain. Among those super intelligent they respect a rule that you don't reveal yourself to younger lives (like star trek).<br><br>2) How long are species intelligent enough to leave the Earth, light up the back side of their planet etc, but not yet super intelligent? It might only be a few centuries. <br><br>So then what are the chances species both in this very short window exist closely enough at the same time period?