It's an interesting point.... but mathematically, or scientifically to be more precise, I would say that it's more likely that if aliens do exist then they are so far far away that contact is hitherto not practical to all intents and purposes. That Hawking is an idiot (ahem..... probably just rubbish bbc reporting as usual... or it's me that's an idiot heh ehhehe hehe ehe ehheheheh hehheh hhehe hhehe ).