I had a thought the other day that sort of blew my mind somewhat. When I talk to people about whether or not they believe in aliens they tend to fall into 3 categories. The first camp says “absolutely not, we are the only living things in the universe”. The next says “Yes! And they routinely visit!”. The last says “I think it’s possible that something is out there somewhere but I think the chances of anyone finding us is so small that it doesn’t really matter if they exist or not”.

I tend to fall into the third group. Given what I know about the size of the universe (as humans perceive it) and what I know about probability I will confidently say that there is some non-zero chance that there is life of some sort elsewhere in the universe. The second half of group three’s argument is essentially based on the fact that there is a lot of space in space. The probability of two races finding each other by pure random chance in something as large as the universe are so close to zero that you could safely believe that we would never make contact with extra-terrestrials and the whole discussion is moot.

But what if it’s not driven by pure random chance? Since taking a recent position as a satellite designer I have been introduced to just how many people in the world are actively looking for “habitable” planets around other stars. Scientists claim to actually have discovered almost 200 planets so far and there are several missions either recently launched or currently in design which expect to find dozens of planets that may be capable of holding life. For the sake of argument, lets assume that those scientists are really smart guys and know what they are talking about. So, if they tell me that a planet 1 parsec away has an atmosphere capable of sustaining life, I will believe them.

Given what I know about technology and how fast it tends to advance, I think I can safely assume that as time goes by we will be able to see any discovered planets with increasingly better resolution. Also, our ability to measure a planets mass, chemical makeup, and atmosphere content will only get better with time.

Now lets fast-forward in time to the day we have the technology to build a ship capable of inter-stellar travel. Where do you suppose we would go? I can only imagine that the first destination on the list would be the planet that we have rated as the most likely to contain some form of life on it. That would eliminate all the random chance from the equation. We would have detected what we think might be life and then set out on a mission to go check it out. If we didn’t find anything we could keep bouncing around to the next place we think there might be life… and so on.

Granted, this would not happen any time in the near future… but the universe is a very old place. What if something else out there detected us a few (hundred?) thousand years ago and are already on there way… or have already been here?