The fact that we exist as carbon based life forms makes it somewhat likely other life forms exist. We're made of the most common elements, whose signatures we o

The fact that we exist as carbon based life forms makes it somewhat likely other life forms exist. We're made of the most common elements, whose signatures we observe in other stars. But in order to exist, we needed time for first and second generation stars to create heavier elements. So, space is only part of the limitation, time may be the more key reason we don't hear alien contact.