As I've said a number of times:
Just because Aliens possess space travel technology does not mean that they are also going to be more advanced than us in all other areas as well. The assumption that this has to be the case is based on the believe that scientific progress is linear, and will be the same for everyone. This is not, and never has been the case.
Scienctific development is primarily guided by the imagination, in general people come up with ideas and then try and find scientific ways of making those ideas a reality. In the course of pursueing that goal, a lot of things are typically discovered by accident. For example there is an entire field of laser technology out there that has influanced everything from medicine, to communications, to visual arts like holograms. All of this was discovered because someone thought zapping ants with a lens was cool, and it would be neat to make a weapon that could do the same thing to people. The rest of the technologies were found playing around with focused beams of light, trying to achieve an imaginitive goal (which people are still working on, the lasers get smaller and more powerful every generation). The odd thing is that there are more efficient ways to kill, but lasers captured the imagination.
The thing is that an Alien species might have had OTHER ideas capture their imagination instead and missed entire areas of scientific inquiry. Space travel might simply be a side effect of another area of research that never captured humanity's imagination.
By the same token, for there to be conflict with aliens there needs to be something to fight over. It's a big assumption to assume that Aliens will want, or need, the same things we do. A species of sentinent, tentlecle equipped floating gasbags that breathe argon for example might have entirely differant needs for colonization from humanity, and have developed tech from an entirely differant perspective using resources that don't conflict with ours... basically, an entirely differant ecosystem.
What's more I feel that to some extent any sentinent being of sufficient advancement is going to ask a lot of questions about morality, the nature of the universe, etc... As the world has advanced for us, moral codes have also changed, arguably one of the big weaknesses we face is simply becoming TOO moral to function effectively. That could very well be a problem for alien species as well.
To put things into perspective, today someone who talks about using a "total war" doctrine (which I do frequently) in current conflicts is a minority opinion. On top of this for all pretensions of empire it takes a lot of effort to motivate people to engage in a conflict, a powerful nation deciding "hey, let's go take over these third world nations and steal all their resources" just doesn't happen that much anymore.
What's more one also has to consider that there were a lot of extenuating circumstances in some of those conflicts between vastly more advanced cultures meeting inferior ones centuries ago. While guys like Columbus were arrogant, and treated savages like savages, it should be noted that most of the REAL bloodshed at least in America didn't take place until much later down the road, after events like the "French and Indian War". You can look at other situations in other parts of the world as well, but one of the big issues facing people today is historical re-inventionism, with people trying to change history to meet their feelings of guilt. For example every year around Thanksgiving, you have some party poopers who miss the point and talk about massacres that happened much later down the pipeline, missing the entire point that to begin with the relations between Natives, and early american settlers were very friendly. Indeed some tribes like the Mohegans were *very* close allies for a very long time, however that ended largely due to greed on the side of the Mohegans. While things could have ended better, even after the fact guys like Chief Uncas are local legends down here in Connecticut. There are places like "Uncas' Leap" where he jumped his horse over a waterfall and lived.
Now I suppose if you collected the most callous behavior globally and used that exclusively as a profile of "this is definatly what would happen", yeah... we'd be looking at a nightmare situation. But in reality such situations weren't as common as many would have you believe.
The point being that when it comes to alien contact, I'm pretty much willing to roll the dice (so to speak).
The bottom line is that for all theorists which range from scientists like Mr. Hawking, to tons of Science Fiction writers, nobody knows for sure. I actually think the "OMG, they will destroy us" theory is not very likely.
Truthfully I look towards some of Larry Niven's concepts about the "Uplifting" of civilizations as being more likely. The idea being that an alien species becomes the patron of less advanced species, sharing technology, in exchange for a percentage of whatever that species in turn discovers. Creating something of a galactic pyramid scheme of vassals and client races. When your dealing with races that are truely alien, though sentinent, there is probably more to be gained in the long term by doing things this way, than to simply come in with Nova Bombs and forced terraforming... assuming the aliens even have that kind of tech. Again look at my point about imagination and the development of science.... Stargate SG-1 touched on this kind of thing somewhat with The Asgard, and them using humans to help solve problems simply because we thought differantly. Slug throwers being a weapon technology that never occured to The Asgard, and proved unusually effective (to begin with) against The Replicators who were used to fighting species who almost universally developed energy based weapons (although in this case, this runs sort of counter to my earlier point about lasers).
Ah well, enough rambling, for those that read this far the simple version is I think the odds are that Hawking is wrong.
