The Empty Skies Problem is: If life exists elsewhere in the universe, and it naturally evolves toward intelligence, where is everyone? Why don't we get radio signals from other civilizations? If it's possible to go out to other stars and colonize other planets, why haven't we seen any evidence of this? Assuming other intelligences, some should have evolved earlier than us, and been able to cross the stars millions of years ago. Hundreds of millions. The galaxy should be thick with aliens, an interstellar Manhattan.
Yet the sky seems empty.
Now some people grumpy pants about how the Large Hadron Collider under Geneva could create a black hole. This black hole could then absorb all the matter it came in contact with. The collider, Geneva, and the Earth.
The nice thing about this theory, is that it could explain why the sky isn't full of evidence of intelligent life. Before a species becomes advanced enough to expand into space, it hits upon the idea to build a Large Hadron Collider. Thus avoiding filling the universe with annoying little space people.
Now if only I can write a story with this premise, and get it published before the Swiss destroy the Earth...
Of course this probably won't happen. But still. Maybe there is another experiment, another collider, another thing that makes it easy to destroy your own planet that intelligent species are sure to stumble across. Sure, it sounds grim, but at least it solves the empty skies problem.
I mean, you can't have everything.