broadcast to the Universe

“Professor Stephen Hawking, the Cambridge cosmologist, warned in 2010 that humans should keep as silent as possible because alien civilisations may be attracted to Earth and have the technology to travel here and exploit its resources. “If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans,” he said.”

Let’s accept for the sake of the argument that an ‘imperialistic and inconsiderate’ civilization (like the western Europeans were during the time of Columbus) manages to reach the technological prowess of being able to travel at velocities higher than the speed of light – otherwise no one would bother to leave their native planet except for a real emergency since building an empire in this circumstances is impractical.
Would you think they would wait for an invitation from us? Or that they would even need one to know that the Earth is a ‘hospitable’ planet?
If ‘they’ are as belligerent as we were, and still are, the Universe would be either divided into at least two empires busily trying to bite each other’s throat or a huge one who continuously gobbles up new and new planets.
We are still free after so many eons since the galaxy has been in place so chances are that either ‘they’ are a lot more peaceful or interstellar travel is not a feasible thing. Not in any recognizable – by us – form of animal life, anyway.

What we are left with is another, and for me a lot more plausible, hypothesis.
Long range travel has indeed been mastered, in one form or another. After a prolonged interstellar war or even from the very beginning the ‘travelers’ have understood that peace is a lot more ‘profitable’/nice/cozy than generalized war so they don’t allow ‘beligerant’ civilizations to get out of their planets until the would be new-comers ‘grow up’ from their ‘waring’ pubescence.
For instance by installing monitoring stations around ‘promising’ planets and actually sabotaging their efforts at ‘conquering the space’ until they reach a comprehensively peaceful stage of social development.

I remember that one of the conditions for Romania to be accepted in both European Union and NATO was for it to have good relations/’friendship treaties’ with all its neighbors. If we were wise enough to do such thing don’t you think that a civilization that has mastered space travel should have reached the same conclusion way back in their development?

It seems that our fright about the ‘aliens’ tells more about the way we are than about anything else…