Sebastiaan gave me a link to an interesting
article by Michio Kaku about the physics of advanced alien
civilizations
(PDF in case the link doesn’t
work) and how far we are of becoming an advanced civilization.

Kaku asks himself the question “How advanced could they possibly be?” and
answers it in this article. He divides civilizations in different types:
Type I, II, and III, which have mastered planetary, stellar and galactic
forms of energy, respectively. Earth’s society is a Type 0 civilization
currently and he expects us to reach level I in about 200 years. Read this
article only if you’re interested in planets!