Are there really aliens in the universe?

There are no aliens in the universe.

Since mankind’s exploration of extraterrestrial life, no traces of extraterrestrial life have been found, let alone aliens. If they really exist, it will be a sensational event around the world. Obviously, whether everyone speculates that there is or does not exist, the result is the same "no evidence".

But science pays attention to evidence. Since no evidence of aliens has been found so far, the answer must be "no". Therefore, from the perspective of existing science, it means no. This does not need to be controversial.