Thanks for the URLs. Very interesting reading.
> Not to sound too pessimistic, but if an alien race did want to conquer us, for
> whatever reason, and they had the means to reach our planet, it would probably
> be not that difficult to do so. A few well-aimed planetoids or comets and we
> would be finished in one form or another - no fancy laser weapons or exotic
> technological bombs required.
It wouldn't even be that hard. Given the advancements we've made in
biological science and assuming a more advanced race would have solved
all the biological problems we're still working on, they could engineer
a germ or something that made all humans infertile. Spray it in to the
atmosphere, come back 100 years later, and take over an empty planet.
No destruction of natural resources or habitat required and no risk to
any of your own species.
Scary thought! Not enough action for a good science fiction story,