As a civilization advances, it tends to let machines do its dirty work. Cars replace horses, nuclear bombs replace infantries, drones replace fighter jets; it’s all about increasing efficiency. This rule of thumb can be generalized as an effort by living things to resist the second law of thermodynamics or the rule that disorder tends to increase in the universe. In fact, “life” is sometimes even defined as an entity that struggles for order. The tenet of physics holds true cosmos-wide, and so any race of beings would be expected to advance in a similar fashion to humans, gradually becoming more and more efficient through the invention of machinery. By the time an alien race is sophisticated enough to trek between stars, they’ll more than likely do it from the comfort of their home planet.
“Chances are, the first invaders will be some sort of artificially intelligent machinery,” Shostak said.