What If?: Serious Scientific Answers to Absurd Hypothetical Questions

by Randall Munroe

I later learned that the reason the sparks didn’t hurt him was that they were tiny; the heat they carried could be absorbed into the body without warming anything more than a tiny patch of skin. The hot molecules in space are like the sparks in my dad’s machine shop; they might be hot or cold, but they’re so small that touching them doesn’t change your temperature much.1 Instead, your heating and cooling is dominated by how much heat you produce and how quickly it pours out of you into the void.

The world is big,[citation needed] but there are a lot of people.[citation needed]

But I’ve never seen the Icarus story as a lesson about the limitations of humans. I see it as a lesson about the limitations of wax as an adhesive.

Here’s a question to give you a sense of scale. Which of the following would be brighter, in terms of the amount of energy delivered to your retina: A supernova, seen from as far away as the Sun is from the Earth, or the detonation of a hydrogen bomb pressed against your eyeball?

The ISS moves so quickly that if you fired a rifle bullet from one end of a football field,7 the International Space Station could cross the length of the field before the bullet traveled 10 yards.

Rule of thumb: One person per square meter is a light crowd, four people per square meter is a mosh pit.

High up in the North in the land called Svithjod, there stands a rock. It is a hundred miles high and a hundred miles wide. Once every thousand years a little bird comes to this rock to sharpen its beak. When the rock has thus been worn away, then a single day of eternity will have gone by. —Hendrik Willem Van Loon

Q. If you call a random phone number and say “God bless you,” what are the chances that the person who answers just sneezed? —Mimi A. It’s hard to find good numbers on this, but it’s probably about 1 in 40,000.