I have what I’m sure are not original answers to the Fermi Paradox as to why we have seen no signs of extraterrestrial life. I may, at a later date go into some of my reasons on why I find fault with the Paradox, but not here.
The first, and simplest, is that it is just not possible to travel between the stars. That there is no ‘Space Drives’. That ‘slow boats’ just can not be made to support life for any extended period of time so it is not possible to travel the decades, or life times, sub-light travel needs. All life is trapped around it’s own star therefor no visits.
I know this is a real downer, but it is a possibility. In the history of science there are many many things that we have wanted to do but we have found out are just not really possible. There is no Philosopher’s Stone that can convert ‘base’ metal into gold. An while we do now how to convert a metal like mercury into gold it takes way to much energy and time to actually do it. An eventually we come to the point of saying ‘why do it?’ In the case of building and meaning a slow boat sub-light craft it may just be that the cost it resources make it totally prohibitive.
On to the second answer. That any contact between life of one planet with another is immediately fatal. That even the slightest contact will kill the visitors. Or even worse kill the live on the planet until the contamination is eliminated (aka destroyed). Once this fact becomes evident to the space fairing Race they will see little reason to visit stars that might have life bearing planets. At best they would be able to exchange ideas, aka information, and at worse create an vengeful enemy thru some tragic accident. Best not run the risk and steer clear of the problem entirely. Wait until they can meet up with someone at a lifeless star where it is safer all round.
So that is it, what do you think?