What If? Serious Scientific Answers to Absurd Hypothetical Questions

Anyone who is familiar with Internet culture has either heard of xkcd, or either encountered one of the webtoon's inimitable comics. Randall Munroe's famous style has spawned a huge variety of comics on science, technology and philosophy, and has helped to make daily webcomics great again.
Right from its inception, xkcd and Munroe were asked to answer a variety of hypothetical scenarios by its readers - ranging from the curious (‘What would happen if a bullet as dense as a neutron star was fired into the Earth?') to the slightly macabre (‘What if the Earth was made entirely of protons and the moon entirely of electrons?'). Munroe started answering these absurd questions with a ton of Math and physics - that is, to say, seriously. The series of QnA was spun-off into a separate section of the site and was termed ‘What If' - this book is simply the entire section in print form, plus previously unseen questions.
Not everything in the book is about anarchy and destruction though - that is reserved for the second half of the book. The first half of the book is comprised of innocuous questions, mostly relating to lightning, time travel, and astronomy.
Even if you're not interested in computation and weird thought experiments, this book is a must-read, if only as a testimony to human imagination. Mind-blowing doesn't even begin to cover it. This is a work of art, and deserves to have space on every bookshelf.