What If? Book answers absurd hypothetical questions

When will Facebook contain more profiles of dead people than of living ones? If a printer could literally print out money, would it have that big an effect on the world? How many unique English tweets are possible?
These are some weird and hypothetical questions which Randall Munroe, creator of stick-figure webcomic xkcd, answers in his new book called "What If: Serious Scientific Answers to Absurd Hypothetical Questions".
Millions visit xkcd.Com each week to read Munroe's webcomic. Fans ask him a lot of strange questions. In pursuit of answers, he runs computer simulations, pores over stacks of declassified military research memos, solves differential equations and consults nuclear reactor operators.

His responses are regarded as masterpieces of clarity and hilarity, complemented by comics. They often predict the complete annihilation of humankind, or at least a really big explosion.
So Facebook may contain more profiles of dead people than of living ones either in the 2060s or 2130s as there are not a lot of dead people on the social networking site, whose majority users are young.
And if a printer could literally print out money, one can print USD 200 million a year, thus having a negligible impact on the Earth. There are 7.8 billion USD 100 bills in circulation.

And Munroe gives the number of unique tweets as 2 x 1046.
He terms his book, published in India by Hachette, as a collection of answers to hypothetical questions.
"These questions were submitted to me through my website wherein in addition to serving as a sort of Dear Abby for mad scientists, I draw xkcd, a stick-figure webcomic," he says.