The following facts are from What If?: Serious Scientific Answers to Absurd Hypothetical Questions by xkcd creator Randall Munroe.
1. Create a global windstorm:
Q: What would happen if the Earth and all terrestrial objects suddenly stopped spinning, but the atmosphere retained its velocity?
A: If the Earth stopped and the air didn't, the result would be a sudden thousand-mile-per-hour wind.
The wind would be highest at the equator, but everyone and everything living between 42 degrees north and 42 degrees south — which includes about 85 percent of the world's population — would suddenly experience supersonic winds.
The highest winds would last for only a few minutes near the surface; friction with the ground would slow them down. However, those few minutes would be long enough to reduce virtually all human structures to ruins.
2. Pitch a baseball at 90% of the speed of light:
Q: What would happen if you tried to hit a baseball pitched at 90 percent the speed of light?
A: Suppose you're watching from a hilltop outside the city. The first thing you would see would be a blinding light, far outshining the sun. This would gradually fade over the course of a few seconds, and a growing fireball would rise into a mushroom cloud. Then, with a great roar, the blast wave would arrive, tearing up trees and shredding houses.
Everything within roughly a mile of the park would be leveled, and a firestorm would engulf the surrounding city. The baseball diamond, now a sizable crater, would be centered a few hundred feet behind the former location of the backstop.
3. Build your own periodic table:
Q: What would happen if you made a periodic table out of cube-shaped bricks, where each brick was made of the corresponding element?
A: You could stack the top two rows without much trouble. The third row would burn you with fire. The fourth row would kill you with toxic smoke. The fifth row would do all that stuff PLUS give you a mild dose of radiation. The sixth row would explode violently, destroying the building in a cloud of radioactive, poisonous fire and dust. Do not build the seventh row.
4. Switch off the sun:
Q: What would happen to the Earth if the sun were suddenly switched off?
A: What would the consequences be for us here on Earth?...
…We would all freeze and die.
5. Have a Richter 15 earthquake hit the United States:
Q: What if a Richter magnitude 15 earthquake were to hit America at, let's say, New York City? What about a Richter 20? 25?
A: A magnitude 15 earthquake would involve the release of almost 1032 joules of energy, which is roughly the gravitational binding energy of the Earth. To put it another way, the Death Star caused a magnitude 15 earthquake on Alderaan.
Sometimes it's nice not to destroy the world for a change.
Randall Munroe, a former NASA roboticist, is the creator of the webcomic xkcd and the author of What If?: Serious Scientific Answers to Absurd Hypothetical Questions and xkcd: volume 0. The International Astronomical Union recently named an asteroid after him; asteroid 4942 Munroe is big enough to cause a mass extinction if it ever hits a planet like Earth.
Excerpt from What If? by Randall Munroe, published by Houghton Mifflin Harcourt on September 2nd, 2014. Copyright © 2014 by xkcd Inc. Used by permission of the author. All rights reserved.
To learn more about What If?, click here.