Aliens must exist

Came across this interview of Helen Sharman (the first British astronaut and first woman to visit the Mir space station):

Aliens exist, there’s no two ways about it. There are so many billions of stars out there in the universe that there must be all sorts of different forms of life. … uch-i-know

Sharman has no uncertainty that aliens exist. However, there must be does not mean any actually exist. So, here is another case where a scientist has complete belief in something where there is no actual empirical evidence for its existence.

Again, if a scientist can believe in the existence of something without any empirical evidence for it, it is not ridiculous for a Christian to believe in God even if there is no supposed empirical evidence.