xMathFanx Their are a lot of solutions. Maybe their is a barry we past or have yet to get to that prevents aliens from adavnsing like say intelligent life is rare then we think or when an alien technology gets to advanced it destroys them and we are approaching that berry. Maybe aliens just stop wanting to spread across the galaxy. Maybe they are so advanced they are every where and we cannot detect them. I mean we do have pretty primitive technology. Maybe they just don't want to interfere with developing races. Or maybe the most scary thought of all we are really all alone. No it is to scary to think about.

I have always held the position that it is not as much a paradox, as a popular misconception with regards to the effects the subject deals with. Here are just a few major objections the "If the aliens were there, we would have already found them" argument:


1) The space is incredibly vast. Even if every galaxy had ~10^15 living beings, the chance of randomly encountering one (assuming they are equally distributed across the space) would be so tiny, we might as well be pointing in a random direction in the ocean and hoping the ocean floor point in that direction holds a drowned credit card with $1m on it.

2) Any alien civilization so advanced as to be able to travel between star systems would have no difficulty concealing their ships from such primitive beings as us.

3) Our technology compared to that of an advanced spacefaring civilization is like comparing an obsidian axe to a nuclear bomb. We cannot even comprehend what kind of energy sources, communication means, etc. advanced civilizations use, hence we cannot know how to look for them.
Modern surveys tend to look for things like radio transmissions... Incredibly short-sighted approach.

4) We are assuming that all intelligent life in the Universe should resemble us. Many even assume that water is necessary for any life in the Universe.
All I can say is that we do not even know all the details of how our own biosphere appeared on Earth. What can we possibly say about other potential forms of existence? It can be anything. Intelligent ocean or a gas cloud? Possibly. Decentralized AI consisting of small pebbles distributed across multiple galaxies? Why not.

5) We underestimate the scale at which civilization develops. We did not even have electricity in our homes 200 years ago.  Our civilization is incredibly young, and we already are fearing that it will soon end due to a horrible mistake on our part. Yet the Universe is 14+ billion years old. The chances of us encountering a civilization at a stage even remotely comparable to ours - is negligibly small.
Any civilization we meet is almost certainly to be either much less developed than us, or much more developed than us. In both cases, we won't know how to interact with them, or even how to look for them.

6) For that matter, we know nothing about how civilizations tend to develop. We are still technologically hairy apes, and our observation sample on civilization development is limited to our own, very primitive civilization. Maybe all civilizations self-destruct in the end. Maybe they reach a technological barrier past which it is practically impossible to develop. Maybe travel far outside one's own star system is impossible due to some physics we are not yet familiar with. Maybe all civilizations are cyclical, repeating the same development cycles and never breaking them due to some fundamental societal problem that plagues every single intelligent being. It can be anything.
We do not know what an advanced civilization would look like, or if it even can exist.

7) Finally, since we do not know what conditions are necessary and sufficient to trigger emergence of intelligent life - we do not even know how many civilizations, even all other points considered, we would expect to encounter. Maybe intelligent life is an incredibly rare anomaly, and the closest civilization to us is a few million light years away. Or maybe it is incredibly common and the life is literally everywhere, in ever square meter of space - we just have not learned to recognize it due to its state of existence being so different from what we are used to.


To conclude, there is no paradox. There is just our complete ignorance on the subject of alien life. Until this ignorance is overcome, we really cannot make any assumptions about what we expect to see in terms of life outside Earth. Incidentally, SETI and other "alien search" surveys, while interesting conceptually, are not very sound as far as pragmatic science goes. We are literally shooting in the sky, hoping to land somewhere, rather than doing any sort of organized search.