Lots of ways to look at it. H.G. Wells was the first to suggest it in "The War of the Worlds." Really, it depends on what the aliens want, what their technological level is compared to ours, and the means by which they plan or are capable of getting what they want.

Look at the reverse angle. Rather than wait for a contact, if there ever will be, we should expand quickly. Economically, the West is in a dead end. Cost competition will reduce most industries to R+D labs run by multinational in secure western countries, and factories where its cheapest. The rest of the jobs will be burgerflippers or management of mulitnationals. Investing in exploration and exploitation of et resources will establish new capital flows that the west can dominate. Also, it'll get mankind of this rock before someone really blows it.

Bombard is right. We need to get off out buts and get out into space. It's going to cost alot of money but it'll eventually make alot of people rich. Private Companies are the ones that need to pick up the pace. NASA, ESA, and the Russians aren't going to ever get us anywhere in the long run. Personally I hope we are the ones that find the aliens, not them finding us.

How would you sleep at night knowing something wants your house for its self ?

I reconcile it by the fact that in all of recorded history, there has been no absolute proof of previous alien contact with humans(there is some ancient, significant evidence to doubt that, but that is going beyond accurate history). The fact that they haven't contacted us yet, or invaded yet, is a decent enough sign we are safe for now. The galaxy is a big place, we have no idea how populated it really is. We could be the only ones out there, for all we know. Or we could have interstellar neighbors next door. Time will tell. Bombard is right, we need to get off this rock, and soon. Otherwise we are begging for a disaster to ruin this little experiment we call human civilization.

Im reading some Larry Niven now. "Footfall" The people didnt even notice them for 15 years while they were in Saturns Orbit

If Earth is invaded in the mext millenia or so it will be by the sovereign states of Jupiter or Mars. If we develop FTL or spacedrive, who knows?

We're not going to be invaded. Reason being for that is that it simply isnt worth it. Our planet doesnt have THAT many resources that an alien culture will need, and what they do need can easily be gotten from other places, such as the asteroid belt or another uninhabited planet. So that leaves the only reason they could possibly have is that we pose a threat to them, and that simply isnt true. We might have a nice big rock in thermonuclear weapons, but we also have the arms of a child, so we really cant throw them that far. So, therefore, we cant pose much of a threat just because we simply cant reach them, and its likely we wont be able to reach them for quite some time to come. And if they DO invade use, we'll be pretty well screwed just because of the fact that it is INCREDIBLY hard to completly conquer a planet, so its likely they will just burn everything to the ground and isolate whoever is left while they go about their business.

None. Any civilization with the technology to travel between the stars will more then capable of defeating our military. Think of the 4th Infantry going up against the XIIth Legion. Only it won't be that close. It will make killing baby seals look dangerous. Think Cortez and the Aztecs only worse. 919( the only possible defense is throwing Maddy Albright clones at them until they beg for mercy. But that is probably against the intergalatic conventions on War).

TankboiKelarius said: "Our planet doesnt have THAT many resources that an alien culture will need, and what they do need can easily be gotten from other places, such as the asteroid belt or another uninhabited planet." Except of course, cheap labor & water.