What If? is a blog by Randall Munroe, the creator of the Stick Figure Comicxkcd. Updated every Tuesday, he answers off-the-wall reader questions using math, science, and xkcd-style cartoons. Randall has a Twitter feed, @whatifnumbers, of numbers he comes up with while writing the blog.Not to be confused with the trope Speculation (formerly known as What If) or WhatIf, a Marvel series speculating on changes to the Marvel universe.
This blog provides examples of the following tropes:
Alt Text: The first few entries didn't have any alt text for the images. However, around the time that "Tie Vote" was published, the author started adding xkcd-style jokes and comments to the alt text. He's since gone back and added them to every single image, but these after-the-fact versions are only short descriptions of the image rather than jokes (although some of them are still funny).
Bait and Switch: In "Bouncy Balls", after noting that a bucket of 3,000 one-inch bouncy balls weighs about as much as a small child, we see a "thought experiment" of a kid being thrown at the hapless test subject, as if the intent is to see the result of the impact of the child and the test subject. The test subject catches the child and admonishes the guy throwing the kid. The guy then chucks yet another one-inch ball at the test subject.
Big "NO!": The pilot in this segment doesn't want to fly a Cessna around different planets and moons in our solar system. The rest of the post makes it clear why it's a potentially awesome and very bad idea.
Will Evans: I was absentmindedly stirring a cup of hot tea, when I got to thinking, "aren't I actually adding kinetic energy into this cup?" I know that stirring does help to cool down the tea, but what if I were to stir it faster? Would I be able to boil a cup of water by stirring? Randall: No.
Randall: If it's going fast enough, a feather can absolutely knock you over. Alt Text of last image: Dude, AGAIN? Can you just pitch like a normal person?
invoked A double brick in "WWII Films". Near the beginning, it goes off on a tangent about IMDb's tagging system, noting that in addition to this making the site a Browser Narcotic, (direct copy-paste, pothole not included) "many people are using the database to catalog every movie containing a scene that satisfies their particular prurient fascination"; a footnote mentions quicksand enthusiasts as an example. Once the entry gets back on track, near the end it hypothesizes a 10-minute movie about the Anglo-Zanzibar War (which lasted only 38 minutes). The very last image is of someone shooting said movie with a phone camera... and labeling it with a bunch of IMDb plot keywords. The Alt Text extends the list of keywords, and the very last one is "possible victim of quicksand".
In "Mariana Trench Explosion" the alt text has, over a picture of the affected area from detonating a nuclear bomb underwater to create waves, "a map showing a thing happening in the atlantic ocean and then another thing happening to the east coast of north america".
In the first entry, the question is "What would happen if you tried to hit a baseball going 90% the speed of light?" The end result is the complete annihilation of the batter, pitcher, ballpark, and everything within a mile radius. But, for what it's worth:
A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered "hit by pitch", and would be eligible to advance to first base.
The entire point of Sunless Earth. Since explanations of what would happen if the sun suddenly went out were both plentiful and not particularly interesting (basically, we'd all freeze and die), Randall instead wrote a long list of awesome things that we'd be able to do if the sun wasn't there...mediated, of course, by the fact that we'd all have frozen to death.
(left hand) Ferret sex at great rates Alt TextMEET SINGLE FERRETS IN YOUR AREA TONIGHT (right hand) Buy my puppy milk, LOL (home row)Galahad has a Flash SSD (top row) We owe it to you to pepper your puppy
Chad Macziewski: What if you strapped C4 to a boomerang? Could this be an effective weapon, or would it be as stupid as it sounds? Randall: Aerodynamics aside, I’m curious what tactical advantage you’re expecting to gain by having the high explosive fly back at you if it misses the target.
Deconstructed Trope: "Everybody Jump" is a question that's been answered by multiple other places including a ScienceBlogs post. However, while Randall comes to the same conclusion for the basic question ("not a damn thing happens"), he then proceeds to tear into it and prove that it would result in a Planetary/Societal Disruption-grade Apocalypse How because nobody would be able to get home, or eat, and civilization would collapse.
Before we go any further, I want to emphasize something: I am not an authority on lightning safety. I am a guy who draws pictures on the internet. I like when things catch fire and explode, which means I do not have your best interests in mind. — Randall, on this page.
disclaimer: i am a cartoonist. if you follow my advice on safety around nuclear materials you probably deserve whatever happens to you. [sic.] — Alt Text of the third picture on this page.
After reading this article, don't try to drive over speed bumps at high speeds. Here are some reasons: • You could hit and kill someone. • It can destroy your tires, suspension, and potentially your entire car. • Have you read any of the other articles on this blog? — Near the beginning of this page.
In "Growth Rate" he gives the birth size of the typical baby as a fraction of the diameter of the Death Star's exhaust port (then as a fraction of the length of a womp rat, in the Alt Text of the corresponding image). Multiple Yodas stacked on top of each other are also used.
Icarus Allusion: Mentions Icarus in a post about how the concept could work on Titan (Saturn's sixth moon, not the mythical giants) but was worried about the wings freezing and falling apart. He figures engineering could solve the freezing issue, and that the real moral of the Icarus tale was not of the limits of humanity, but of the limits of wax as an adhesive.
I Fell for Hours: Averted. As demonstrated in "Free Fall" jumping off the tallest sheer cliff in the world would only result in 26 seconds of air time.
"If you're like me, when you first saw this question, you might've imagined the puck leaving a cartoon-style hockey-puck-shaped hole. But that's because our intuitions are shaky about how materials react at very high speeds. Instead, a different mental picture might be more accurate: Imagine throwing a ripe tomato—as hard as you can—at a cake."
I can pick up a mole (animal) and throw it. Anything I can throw weighs one pound. One pound is one kilogram. The number 602,214,129,000,000,000,000,000 looks about twice as long as a trillion, which means it’s about a trillion trillion. I happen to remember that a trillion trillion kilograms is how much a planet weighs.
...if anyone asks, I did not tell you it was ok to do math like this.
Randall: The lesson: If the optimist says the glass is half full, and the pessimist says the glass is half empty, the physicist ducks.
Missing Steps Plan:"Pyramid Energy", asking if the energy it took to build the Great Pyramid would be enough to send a mission to the moon and back, uses this in the second image. Said image consists of the pyramid broken down and fed through a box marked "?", then launching a rocket.
Moving the Goalposts: Done in "Train Loop" in order to allow for an interesting answer (as in, other than "no"). "Could a high-speed train run through a vertical loop, like a rollercoaster, with the passengers staying comfortable?" becomes (changes bolded) "Could a modified and reinforced high-speed train with a jet engine on top run through a vertical loop, like a rollercoaster, with the passengers surviving?"
Mythology Gag: Since the illustrative diagrams are drawn in the same style as xkcd, they sometimes feature guest appearances by characters from there.
Most obviously, the Black Hat Guy has made several appearances.
The Alt Text for 21 of the planetary bodies ("Interplanetary Cessna") has the pilot being Killed Mid-Sentence. Sadly, Randal removed the image map making Alt Text for different parts of the image possible (presumably to reduce the load on his webserver), causing the Alt Texts to be lost. Thus, we present all 32 of them here:
Sun: [fwoosh] Jupiter: why did you send me here Saturn: i'm not sure this is better Uranus: this planet is the george lucas prequel version of neptune Neptune: blue is good. stick with blue. Earth: it's hard to fly on earth because i don't actually know how to fly this thing. Venus: aaaaaaaaaaaaaaaaaaa Mars: do we actually have to do this? we have the simulations. Ganymede: crap, there's no-- Titan:wheeeeee! hmm, it's getting chilly. Mercury: another one with no atm-- Callisto: aaaaaaaaAAAAAAAAA Io: the ugliest solar system body Moon: ok do we really hav-- Europa: do we have to do all-- Triton: wait can we-- Eris: not ANOTHER one with-- Pluto: ok listen i didn't-- Titania: i didn't sign up for-- Rhea: sign up for-- Oberon: WILL YOU STOP-- Haumea: STOP THIS FOR-- Iapetus: not another-- "Snow White": AAAAAAAA-- Charon: charon made the cut? Umbriel: i don't even know where-- Ariel:are we almost don-- 2002 TC3O2R: this one doesn't even have a name! Dione: just let me-- Tethys: what are you tr-- Sedna: are you trying to pro-- Ceres:you could have done just 10. you seriously could have done just 10.
Reality Ensues: A segment asked if you swam in a spent fuel pool of a nuclear facility, how deep would you have to dive to suffer fatal radiation poisoning? After the physics filled conjecture suggesting that you'd be pretty safe as long as you stayed away from the casks, Randall then asks a real life friend who works at a research reactor what would happen if he tried to swim in their pool.
Friend's response: "In our reactor? You’d die pretty quickly, before reaching the water, from gunshot wounds."
Recoil Boost: "Machine Gun Jetpack" provides the page picture and is Exactly What It Says on the Tin: how much gun do you need to launch yourself into the air? It turns out that an AK47 has a higher thrust-to-weight ratio than the Saturn V rocket, though bringing more than 250 rounds of ammunition would not work well.
A recurring theme, frequently after the question is answered as asked, Black Hat Guy comes in and asks some variation of, "What if we did more?" Several times. Any topic that can be pushed to extremes (that isn't already) will be pushed to those extremes and then some.
"Dropping a Mountain" shows why this doesn't work in real life. After a series of Up To Elevens where Mount McKinley is lifted and dropped from increasing heights, it is taken to the edge of Earth's gravitational well, the highest point an object could fall from, and hits Alaska at 10 km/s. The Black Hat Guy asks to drop it from even higher, which fails because Earth no longer has enough gravitational force to overcome that of other bodies in the solar system. Randall even hangs a lampshade on it.
Black Hat Guy: What if we dropped it from higher up? Randall: Oh. You again. Alt Text: I see where this is going.
The second time Black Hat Guy says it, the alt text is "Fine, but put your hat under it, first." Then, near the end:
Randall: And that's that. We've dropped the mountain from as high as it can be dropped, and I hope John-Clark is proud of the resulting devastation. Thanks for reading, and— BHG: What if we dropped it from higher up? Alt Text: I'M BACK Randall: No, that doesn't actually make sense. The Earth's gravitational pull doesn't— BHG: What if we dropped it from higher up? Alt Text: I DIDN'T DIE WHEN THE MOUNTAIN FELL Randall: Dropping it from higher up won't do anything; there won't be enough force pulling it toward the— BHG: What if we dropped it from higher up? Alt Text: I WILL NEVER DIE Randall: Ok. Fine. You win. We'll try it.
Sequel Hook: From "Free Fall", Randall decides that people jumping off a cliff land in a pit of cotton candy, then wonders in a parenthetical if that would work.
Tim Taylor Technology: A number of the questions get MythBusters-esque answers amounting to "What would happen? Not very much. But that's no fun, let's ramp up the power until something crazy happens!"
The Triple: The first image of "Free Fall" labels the parts of Mount Thor with "East Slope", "Summit", and "AAAAAAAAAAAAA" (pointing at the sheer cliff).