>grey goo (level 10)
A sci-fi doomsday scenario. A nanobot is created and given a simple set of instructions: Find materials. Disassemble materials. Construct more nanobots from materials. Repeat.
The result is a swarm of nanobots consuming everything in their path and creating more of themselves. It's called grey goo because the resulting mass of nanobots would look exactly like that. With exponential growth an entire planet could quickly be consumed.
>China never went communist (level 11)
I-IT WASN'T REAL COMMUNISM!!
>Library of Babel (level 12)
A 1941 short-story by Jorge Luis Borges. The story introduces the library: an infinite expanse of identical hexagonal rooms. Each room has 4 bookshelves filled with books, each book is 410 pages, and each page is a completely random arrangement of the english alphabet, including dots and commas. The library stretches on infinitely, and thus contains every single combination of the 22 letters.
Therefore, the library contains every single text that has ever been written and ever will be written. Every single book is there somewhere, every single password, every single conversation, every secret, every thought. The exact time and place of your death is there, somewhere among the gibberish.
The story inspired a website of the same name (http://libraryofbabel.info/) where you can go right now and explore the bookshelves. Every book in the library is randomly generated, but it is also possible to search for a specific text.