In a universe as massive as our own, it would be selfish to even fathom the possibility of solitude in such an astronomical place. If we are truly alone, then what's with all the wasted space? Allow me to change perspectives for a moment. Let's hypothetically say you just built an aquarium the entire size of Earth. But instead of keeping billions of fish in the giant tank, you've decided to let one measly goldfish reign alone over it's very private sea. As you can clearly see, both ideas of loneliness are one in the same. Only the selfish would believe that we Earthlings have the entire Universe all to ourselves. But did you know we already have suggestive proof of life lurking in our own Solar System? To see it for yourself, all you have to do is look up. Our own Sun can literally help shed some light on this rather dim subject.
Our closest star, the Sun, is just beyond our reach at 93 million miles away. Light from the Sun takes only 8 minutes to bathe Earth with it's awesome power. This light is a necessity for life to have in order to exist. By soaking up water, another byproduct of the Sun, plants also soak up light from the Sun and emit oxygen as it's waste product. Without this wasted oxygen, we Earthlings would surely parish. But thanks to our closest star, everyday life on Earth abundantly thrives. As Earthlings, we know first hand exactly what a star is capable of. Given the right conditions, the marriage of star and a planet can and do produce life as we know it.
We may not have definitive proof of life outside of Earth just yet, but that does not mean life abroad doesn't exist. The fact alone that our Universe contains billions of stars making up billions of galaxies, I would say that it's not possible for alien life not to exist in such a massive universe. But until we find that definitive proof of life beyond Earth, the question of are we alone in the Universe will still go unanswered. But perhaps on a planet, in a galaxy far far away, that very same question also plagues advanced minds just as ours have for centuries.