Lecture and book by Sir Martin Rees http://www.youtube.com/watch?v=3qF26MbYgOA
After some 6 billion years the Sun will die. But before that happens, any type of intelligence that exists then will be as different from us as we are different from bacteria.
Our century is very very special: humans can change themselves. Any scientific discovery has benign consequencies as well as dangerous ones. We have to accept the risks if we are going to enjoy the benefits of science.