These can be very stupid questions; but I always ponder over it 1. Is this our assumption that extra terrestrial life will have same chemistry/ biology/ consciousness as human beings? 2. What is definition of Life and Intelligence for E.T life. The phenomenon what we call life can be completely different for E.T. being. This is more or less same as que 1 3. It seems we have also assumed that our civilisation is advanced. In terms of what? Is our definition of advancement (and also civilisation) applicable to E.T life? 4. Consider a highly advanced civilisation millions of light years away from us finds Pioneer plaques. Even after finding these plaques they don't (wish to ;-)) communicate with us... does it mean that civilisation is not sufficiently advanced?