Stephen Hawking Is Terrified Of An Alien Invasion, And The Reason Makes Nothing But Sense

[Shankapotomus]

49. ^This

Any alien civilization scientifically advanced enough to cross the Universe would probably be incredibly peaceful.

In order to create such technology you'd have to get your planet's resources under a unified direction. And in order to do that you'd have to overcome competition on your planet for those resources so they can be managed effectively. That means your species has long stopped wasting its resources on wars competing for them and its efforts all go to non-military scientific research and development. A peaceful civilization, one cooperating on a global scale and in peaceful management of its resources, is going to be what it takes to organize and direct technology for interstellar travel.

Such a civilization would be used to existing on that cooperative level and would probably be afraid to contact us as we are afraid to enter a gorilla exhibit at a zoo. They would conclude we do not know enough about cooperating to interact with us.