The question of whether we are alone in this universe has gone on for a long time. One can even trace it back to as far as when humans started recording history, of course we probably thought of such things before that time.Such question has fascinated humans for centuries inspiring a quest for such knowledge.
Astronomy emerged as a method to acquire such knowledge. For once there was a field dedicated to the studying of the skies. Astronomy over time evolved from studying stars through telescopes here on earth to telescopes out in space; expanding our understanding of such skies to include an entity much larger then we could have ever imagined.
Once we realized such a huge entity, we gave it a name-the universe. Most people however don't understand the magnitude of how big it is. The size of the universe is indeed the answer to our question of whether in fact we are alone in the universe?
Our planet belongs to one solar system, such a system has at the center our sun with earth and other planets circling around it. But our sun is just one star out of the billions if not trillions of stars in our galaxy; each star respectively has its own planets, moons, and satellites which form its solar system. But it doesn't stop there, our galaxy is one of a billion if not trillion of galaxies clustered together in a super galaxy; you would think it would stop there but it doesn't,such a super galaxy is once again one out of a billion if not trillion super galaxies which can be theoretically called super super galaxies. However current science stops here we can't determine what is farther out there than this because we are unable to see this far.
Space is huge. It is so huge the nearest stars are light years away. A light year is the distance one would travel in a year going at the speed of light. We don't have the technology yet to even go a fraction of the speed of light not even 1% of its speed; this has limited how far we can explore, limiting us to our solar system.
Some scientists would argue that earth is unique because out of all the planets earth is the only one habitable; they would also argue that the chances of the conditions present on our planet when it started forming and the conditions which sustain life to be present in other planets would be very rare if not non existent. The only problem with such a theory is that it forgets to take into consideration the size of the universe, such a size in fact not only gives the possibility of there being life out there but it's size is so big that it makes it impossible for there to be no life in the universe other then our own.
So why do we have no evidence of life being out their in the universe? Why have our satellites not detected anything out there? Or why haven't we been visited by aliens? Many things can explain this, technology for one can explain this. Either our technology is too primitive to attract any other life forms or it is too advanced for other life forms to detect. What about the possibility of the knowledge we posses as humans is totally different from other life forms. Such a problem would make communication between us and them impossible. What we might consider as math might not even exist in their world, their bodies might be composed of different elements acquiring them to use different methods of sensory they might be so unlike us that we don't know what to check for.
One day technology might be able to prove that there indeed is life out there. But until then we must blindly accept that life does exist out there. Humans throughout history have made pretty blunt assumptions, the sun revolving around the earth, the earth being flat, all thanks to our lack of technology and understanding. However as technology improved we were able to diminish such assumed truths and replace them with facts, even though it contradicted everything we ever believed in. We have to understand that we are still incapable of proving that no life exists out there in the universe and that the probability of there being life out there is much greater.