The search for life in the universe is one of the most challenging
topics of science. It is not a modern topic at all, since more than 100
years ago, it was speculated that on the Moon, there are oceans and
seas; on Venus, there are swamps and also Mars is inhabitated. However,
now we have the scienti?c background and the scienti?c tools to answer
this question and it is also certain that the answer would have deep
imp- cations for our culture, philosophy, and religions. If we ?nd that
life has developed on other planets or satellites of giant planets, then
this would be the ?nal breakdown of our central position in the
universe. But is life a widespread phenomenon? How vulnerable is it to
changing conditions and even catastrophic events? These topics will be
discussed in this book. If life is in the extreme case a unique
phenomenon found only on planet Earth, which seems to be highly
unrealistic, then also it is important to discuss how it is adaptable to
changing external conditions. Can we survive a cosmic catastrophe? How
do these catastrophes change habitability? Which forms of life are more
v- nerable? It was mentioned that now science has made great progress to
answer such qu- tions. Let us give some examples. In modern biology, in
connection with organic chemistry, the origin of life is studied.