And yet we are all alone.......no aliens.
No Aliens who have bothered to (a) come and have a look at us, and/or (b) make themselves known to us. If they are sufficiently advanced to have mastered FTL travel, it's unlikely that we would even recognise them as life forms. Does an ant recognise a human?
And if they haven't mastered FTL, then if they were expanding beyond their own solar system, it's mostly likely that they be mining asteroid and building Orbitals or Dyson Spheres around local stars before bothering to come and have a look at us - especially when you think that the first transmissions any alien civilisations might have detected from us are the TV broadcasts of Hitler's speeches at Munich. We're hardly an attractive proposition based on that.
I quite like Cixin Liu's 'Dark Forest' theory, and Alistair Reynold's Inhibitor theory too. Both pretty interesting hypotheses as to why advanced alien civilisations would do everything they could to avoid being discovered.
