I have to admit I had a chuckle at the comment on page one that "there's trillions of other planets out there." Yes it's technically correct but underestimating it significantly. It's the same as saying there are "dozens of other planets" - there are but it grossly understates the number. Quadrillions, quintillions, sextillions, septillions - none of them come close to reflecting the real number.
I think it's almost certain their is other life in the universe. 99.9% (recurring) sure. There's always an element of doubt because until we have proof we have to allow for the very slim possibility there isn't.
People make many mistakes in falsely equating our current lack of proof as meaning we are alone. One, the distances are huge. Two, life is likely to exist in many places, so there is no specific reason for an alien species to happen to visit us.
Three, think about how old this planet is. Humans have only existed for a tiny proportion of our planet's existence. For most of our history we wouldn't have recorded alien visits anyway. Further, it's only in the last century or so that we've been sending and receiving radio messages. Any messages targeted at us would have gone unanswered. Messages we've sent will take millenia to reach other civilizations and their responses will take millenia to come back. Assuming we can understand each other and the other civilization is at a point where they can and want to reply. Large areas of our planet are still empty and aliens could visit undetected. Yes we have radar and so on, but think about missing flight MH370 - we couldn't even track a plane reliably when it veered off course. A plane we knew existed and one which complied fully with our knowledge of physics.
It's remarkably unlikely that an alien race would decide to visit this planet in this solar system in this galaxy in this part of the universe at this point in time.
Let's make some sweeping and inaccurate assumptions. Suppose 1 in 10 planets are capable of supporting life. Of those 1 in 10 will actually develop life. Of those 1 in 10 will develop intelligent life. Of those 1 in 10 will exist for a few hundred thousand years without being wiped out by disease or asteroid impact or natural disaster. Of those 1 in 10 will have a civilization that evolves to the point of taking its first steps in space travel. Of those 1 in 10 will develop the capability to travel vast distances in space. We've already whittled 1 in 10 down to 1 in a million, and the real numbers would be much less than 1 in 10.
Life almost certainly exists out there but intelligent life which has the capability and interest in contacting us is likely to be extremely rare. We've never travelled beyond the moon. Next up is Mars. It will be a very long time before we would be capable of visiting another solar system, let alone cast the net much wider.