📖 Why Haven't We Seen Aliens?

If there really is alien life elsewhere in the Universe, then it's reasonable to ask why we haven't seen it. Surely our planet Earth would have been visited by aliens by now? Does that mean that alien life doesn't exist? This book uses some simple maths to take a sober look at the chances of our actually meeting alien life. After all, we will only meet up if both we and they are in the right place at the right time. The Universe is a big place - and it has been around for a long time. Perhaps we were out when they visited us.