The chances we give a definitive answer to the eternal question whether we are alone in the universe in the current century are yet very slim. Nevertheless, there are many scientists that suggest otherwise.
According to some experts in the scientific fields of astronomy and astrophysics human knowledge has never stopped expanding since the very beginning of our existence. For example, nearly 15 years ago we believed that there is no other planet like the Earth but scientists have already observed nearly 800 other planets that are orbiting around stars in our own Milky Way Galaxy. What is special about these planets is that they could potentially have liquid water due to their appropriate proximity to their stars which provides the necessary life harboring conditions .
Another reassuring reason for believing there is an alien life form out there is the mind-boggling number of stars in the universe. Based just on statistical evidence there is a probable chance that a planet which has gone through the same evolutionary processes like our Earth really exists.
Last but not least, scientists are encouraged that we will discover alien life forms one day just because we have already done it in a way multiple times here on Earth. We have discovered numerous lifeforms that are flourishing in the most extreme environments. Raging from extremely hot to cold to extremely dense, life tends to always find a way to survive.