The universe is 13.8 Billion years old, so we can only observe the universe 13 Billion light years away. However the universe is practically infinite and much l

The universe is 13.8 Billion years old, so we can only observe the universe 13 Billion light years away. However the universe is practically infinite and much larger than the observable universe. It's not possible for us to detect a galaxy and a civilization (if it exists) in the said galaxy outside the observable range. Similarly, for the said civilization we lie outside that observable range and they can't detect us because nothing can travel faster than the speed of light. Now imagine, how huge the unobservable universe is. Probabilistically, it is quite possible for a civilization (or multiple) more or less advanced than us to exist far, far away, or may have existed some point in time. But none can detect each other. Its even possible for a civilization to exist in the spheres of observation of other civilizations but so far away that its almost impossible to make contact. 13.8 Billion years is not a long time on the scale of the universe, but it is also a long time on evolutionary scale for a civilization to have existed and have been extinct.