Home > Clement's Game > Science Fiction Round 37: What If?

Science Fiction Round 37: What If?

Randall Munroe of XKCD wrote a book called What If?, based on the same segment on his website as well as a number of questions not posted on the web.

And it is amazing.

It’s also a little difficult to classify.  It’s being sold as non-fiction, but I’m putting it under our local sci-fi listing, in large part because it has a lot of segments that start with absurd, impossible proposals before attempting to follow them to their logical (and frequently world-ending) conclusions.


Apocalypse How

There are a surprisingly large number of ways for everyone to die horribly.  Munroe focuses on the planetary-level destruction and smaller, for the most part.

The options range from global windstorms to near-lightspeed baseballs to turning off the Sun to draining the oceans using a magic portal between Earth and Mars.

I think the reason for this is simple: if someone wants to ask an interesting but impossible what-if scenario, they either go big or go home.  Why slow the Earth down a little bit when you can stop it from spinning completely?  Others — such as the baseball traveling near light-speed and the giant raindrop — result in disasters comparable to the amount of energy involved in each scenario.  Which often ends up being impressively large.

But, on the smaller and more personal scale…

Don’t Try This At Home, Kids

And also a surprisingly large number of things that are a very bad idea to try in practice.

For instance, swimming in a pool containing spent nuclear fuel rods.  Not recommended.  For various reasons, ranging from “don’t get too close to the radioactive bits” to “the security folks won’t let you in.”  But this is something that’s actually done — very carefully, to perform needed maintenance in the pool, with workers whose dive suits are layered in radiation sensors.

A large number of the questions also involve dropping people or things from orbit/assorted high places, and seeing what happens.  I think these are also an understandable set of questions — falling is both fascinating and terrifying.

Also, I don’t care how many helium canisters and how large a balloon you’re filling with them, don’t jump off a building with all that.  Especially with the plan of filling the balloon before you hit the bottom.


Of course, this being our job, it’s time for complaining about minutia.

In the very first section, I think he gets the direction of the horrible winds and waves wrong.  The question suggests that the Earth stops spinning entirely, but the atmosphere keeps going.  The Earth normally spins counter-clockwise around its axis, which makes the sun rise in the east in the mornings as it should.  If the Earth stopped, but the atmosphere keeps going, the air should be going in that same direction — west to east.  From Munroe’s description, it sounds like he has the impossible winds going in the other direction.

Second, although he gets it right, I was curious enough to check: would crunching the entire mass of the Empire State Building into a bullet-sized object have strong enough gravity on the surface that a human couldn’t pull away from it?

According to the Internet, the building has a mass of roughly 400 million kilograms.  A distance of 1 cm away from such a mass (it’s a large bullet, to make the math easier), the acceleration from gravity is a = Gm/r^2, which actually ends up being about 270 m/s, or about 27 g’s.  Holy cow!  That is, it’d feel like your fingertip weighed 27 times as much… and that’s way more force than even fighter pilots handle.  Nope, don’t touch that.


Read them.  They’re one of the most hilarious parts, whether debating the correct spelling and punctuation for “LEGOs” or making requests for a time-travel pickup.

I was particularly impressed by one footnote, which led me on an unfortunate wikipedia search: there’s a kind of salamander that reproduces entirely by self-fertilization.  It’s called Tremblay’s salamander, and yes, all the members of the species are female.  They’re a hybrid of two other species of salamander, and reproduce by what Wikipedia calls kleptogenesis — they need males from one of the other species to stimulate ovulation, but that’s it.  Their genes go nowhere.  Oh, and the Tremblay’s salamanders have three sets of chromosomes, instead of just two, which helps with the inevitable inbreeding problem.

Further, there’s a second species, called the Silvery Salamander, which does the same kind of thing as Tremblay’s, and is descended from the same two initial species of salamander.

So, let’s end on a cute note — the Ann Arbor city website suggests that this is a Tremblay’s salamander:

Aw, isn't she cute?

Aw, isn’t she cute?  Also, she is not likely to destroy the world using any of the scenarios in Munroe’s book.

  1. 2014/10/18 at 7:01 pm

    Nice review. I did not catch that east-west slip. I’ve started trying to tackle the questions Randall wouldn’t answer on my blog, starting with the infamous teeth question. (Answer: no, it’s probably not possible.)

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