2712: Gravity

2022-12-20T20:15:56Z

Eschew Obfuscation: Fixed a minor typo.

{{comic
| number = 2712
| date = December 16, 2022
| title = Gravity
| image = gravity_2x.png
| titletext = It's a long way down.
}}

*To experience the interactivity, visit the [http://xkcd.com/2712/ original comic].
==Explanation==
{{incomplete|Created by THE UNIVERSE FROM A PIECE OF FAIRY CAKE- Please continue expanding and describing the various bodies. Do NOT delete this tag too soon.}}
In this interactive comic, the viewer pilots a small spaceship throughout a vast area in space. The viewer is capable of exploring various bodies and planets within the play area, many containing easter eggs alluding to the book What If? 2 and previous xkcd comics. The flight mechanics are largely, if not entirely, Newtonian, so the vessel is capable of using the gravity of planets to alter its trajectory or even enter orbit. The spaceship has indicator circles around it which appear when a gravitational body comes into range, showing the direction towards their center of gravity and the size of the body. A circle also appears around the spaceship whenever it collides with a gravitational body, acting as a shield. The shield remains until the player orients the spaceship upright so its landing gear can deploy.

With a keyboard the arrow keys rotate the spaceship and accelerate it forward and backward. You can also use the standard first person shooter keys 'w', 'a', 's' and 'd', and the standard vi text editor navigation keys 'h', 'j', 'k', and 'l' to control the spaceship. Despite some ships having no unique backward texture, all ships can reverse. On mobile the comic will full screen, pressing either side of the center rotates the spaceship, and pressing in the center accelerates it forward.

It is fairly easy to fly between planets as long as you pay attention to orbital mechanics; don't just floor the accelerator. The background stars show your velocity and orientation relative to the nearest gravity well. If you are having difficulties navigating space, point towards a gravity orb and accelerate for only a few seconds. Wait until the background stars spin wildly, and then reduce your velocity to 0 before gently accelerating towards the object.

'''Playing on mobile:''' Various additional glitches may occur. Having a starting position slightly below the take-off pad means you're already 'glitched' inside the planet from the off. Escaping the planet may need inverted 'accelerating' (turning perpendicular to the local vertical, and thrusting ''backwards'' until you can glitch back out into more open space. You may also be trapped within the cannonball 'orbit', with seemingly inconsistent collision-detection, such that you can be sat ''with landing gear extended'' upon features (projectile tracks, etc) that seem not to count as solid for most other purposes.

There is no "universal" point of view — the bottom of the window, "down", is oriented towards the object exerting the most gravity upon the player. Multiple things found in this comic draw attention to this, such as how on Earth Ponytail says to White Hat, "I checked downforeveryoneorjustme.com and it says just me", and he replies "Yeah, I guess down isn't down for everyone."

Throughout the play area are coins that change the spaceship into different rockets and non-space based vehicles, including humans.

The comic promotes Randall's new book [https://xkcd.com/what-if-2/ What If? 2], which was released in September and is available for purchase. Many of the planets contain references to various What If? articles.

The comic is similar to [[1608: Hoverboard]], which celebrated Thing Explainer instead.

===Celestial Bodies===

The following is an incomplete table of features:

{|class="wikitable sortable"
!
!
!
!
! colspan="4"|References
!
|-
! ID
! Description
! Transcript
! Tiles (X, Y)
! What If
! XKCD
! Movies
! Other
! Explanation
|-
|<code>origin</code>
|'''Starting planet'''
|
Cueball: "To celebrate the world of ''What If? 2'', here is your very own tiny planet to explore!

Megan: "Welcome!"

Ground caption: "Give someone the science question-and-answer book ''What If? 2'' for the Holidays: xkcd.com/whatif2"

Cueball feeding T-Rex: "Burger?"

Isaac Newton: "Robert Hooke must be down there ''somewhere!''"

Megan to Cueball: "If you ever get lost in space, just fly down. That's where the ground is."

Beret Guy to squirrel: "Hi!"
|(0, 0)
|Y
|
|
|Y
|The starting planet. The player begins on the launch pad in a landed position. Collecting the orbiting cannonball will transform you into a different rocket, although it does not improve your abilities.

Cueball feeding the T-Rex is possibly a reference to What If #78: {{what if|78|T-rex Calories}}.

{{w|Isaac Newton}} is referencing the {{w|Newton's cannonball}} thought experiment, where a cannon is fired at greater and greater speeds until the cannonball goes into orbit. Newton's comment suggests that instead of demonstrating orbits, he is firing repeatedly to hit his rival, {{w|Robert Hooke}}.
|-
|<code>earth</code>
|'''Earth'''
|
"How am I supposed to cause the extinction of the dinosaurs if they keep moving out from under my comet?"

"Unusually high-speed squirrels."

"Jump in! The water's fine!"

"Ugh, the frame rate is really bad out today."

"I don't know why people complain about going down rabbit holes. These lil guys are adorable!"

"Ahh, the mysterious natural wonders of sailing stones"

"I'm Bananas Georg.
Every year our company publishes global per capita banana consumption numbers, so to make the printing easier, I eat enough bananas of December 31st to make sure it's a round number."

"Weird, I feel ''heavier''."

"Hey"

"I checked downforeveryoneorjustme.com and it says just me"
"Yeah, I guess down isn't down for everyone"
|(27867,-35648)
|Y
|Y
|
|Y
|A planet with among other things:
* A [https://what-if.xkcd.com/162/ crane dropping a comet] onto a dinosaur,
* Unusually high speed squirrels (creating a sonic boom)
* Megan inviting Cueball into a pool
* A region where the frame rate is intentionally limited
* A flagpole
* A literal {{w|burrow|rabbithole}} referencing the figuratively speaking [[wikt:rabbit hole|rabbit hole]]
* Someone aiming at a satellite with an arrow
* A lake with an eel
* The [https://what-if.xkcd.com/157/ earth-moon firepole]
* A "doot cone," a reference to [[Volcano Types]]
* Two figures being attacked by a third with a sword
* Two kids playing soccer (Catching the ball will turn the ship into a soccer ball)
* A farmer on a tractor being stuck in gooey candy
* A banana pile being consumed by "Bananas Georg" to make the per capita annual banana count round, referencing the "[https://reallyreallyreallytrying.tumblr.com/post/40033025233/average-person-eats-3-spiders-a-year-factoid Spiders Georg]" meme.
* Megan and Cueball digging a hole (in the center of this planet is the "earth's core", referenced below)
* The [https://what-if.xkcd.com/147/ Niagara Falls water being redirected into the LHC] (Large Hadron Collider)
* Japan(?) leaving earth
* A tube to the bottom of the ocean
* Ponytail and White Hat making a reference to [downforeveryoneorjustme.com]
* Two mini asteroid moons: A tiny version of B612 with Little Prince and the rose, plus one with just Cueball standing on it. They can be found by flying straight up from the Super Mario flagpole.
|-
|
|Earth's core
|
| (28850, -28570)
|
|
|
|
|[[Cueball]] and [[Megan]] floating in a small space in the center of the planet in inverted rotations. Can be legally accessed using a high velocity collision onto the surface of the planet, although requires tapping the up arrow afterwards many, many times.
|-
|<code>europa</code>
|'''Europa'''
|
|(13180, -2540)
|Y
|
|
|Y
|Europa, one of Jupiter's many moons (in real life). A broken, icy crust has a single path into its core.
|-
|
|Europa's crust
|
"It's so unfair we don't get to compete in EuroVision."

"The region of the solar system where liquid water can exist on the surface is the habitable zone, and the region where it can exist beneath the surface of moons is the Eurozone."

"WHIRRRR"
|
|Y
|
|
|
|Europa's crust, with a single entrance into the core demarcated by an octopus leaving a hole.
Cueball states that Europa is in the Eurozone, a pun on the ''other'' Eurozone, with liquid underneath its surface.

A roomba whirs across the icy crust.

Cueball has a hairdryer and is melting the surface of the crust. A direct reference to [https://what-if.xkcd.com/35/ What If's Hairdryer].
|-
|
|Europa's core
|"We've always used neutrinos for astronomy, but if we place my 'optical telescope' in orbit above the kryosphere, we could potentially observe the universe using electromagnetic waves. Who knows what else there is out there besides stars! There could be other worlds!"

"Hi, I'm Annie. Welcome to the depths of Europa. There's some weird stuff down here."

"We were caught in a powerful November gale on the Great Lakes outside Whitefish Bay. Our ship foundered and sank here." "This is Jupiter's moon Europa." "It was a REALLY powerful gale."

"Does our book club really need this much secrecy?" "That sounds like a question a SPY would ask."
|
|
|
|
|
|A watery ocean with octopi looking out into the great unknown using telescopes. This is a reference to octopus's intelligence here on earth! It may also be a reference to (Spoilers!) a certain 2013 science-fiction film featuring Europa, if not a 1987 book. There's also a secret path leading to a book club, through the wreck of the Edmund Fitzgerald.

The woman presenting herself as Annie is a reference to Annie Rauwerda, the creator of the popular social media accounts [https://en.wikipedia.org/wiki/Depths_of_Wikipedia Depths of Wikipedia].
|-
|<code>b612</code>
|'''B-612'''
|
Probe: "Asteroid deflection mission to earth. The package is delivered. Commencing planetary threat neutralization."

Sign: "Welcome to B-612"
|(2610,3700)
|y
|Y
|
|Y
|A reference to [[618: Asteroid|Asteroid]]. In a tragic turn of events, the Earth-bound asteroid being blown up is the home of [https://en.wikipedia.org/wiki/The_Little_Prince the little prince].
|-
|<code>dogplanet</code>
|'''Dog park planet'''
|
[Dog Park]

"I want more dogs!"

"Ball! Again!"

"I hope it lands soon."

"English adjective order means that you're "Clifford the Red Big Dog" but not "Clifford the Red Big Dog""[sic]

"You can't have too many dogs!"

|(1240, 11230)
|y
|
|
|
|A planet covered in dogs, along with dog walkers, some fences, and a sign that reads "Dog Park". Two dogs watch a ball which is traveling in what appears to be a circular orbit around the planet. One dog is much larger than anything else on the planet. A hole is being dug by two dogs. Visible at the bottom, there is an empty space in the center of the planet in the shape of a dog bone.
|-
| <code>goodhart</code>
|'''What If? 2 scenario planet'''
|
Cueball to White Hat: "The tower over there is the Vehicle Assembly Building, and then behind it is the Vehicle Disassembly Building."

Ponytail to Cueball: "You know how tires pollute the environment with rubber particles? Well, I've developed a solution."

"MMM SPIDERS HOMF HOMF"

Shooting star caption: "THE MORE YOU KNOW"
Sauropod: "Oh no!"

Person on uncontrolled helicopter: "AAAAAA"

Geyser: "Fwoosh!"
Cueball and Megan: "Oooh!"

Giant phone crushing city: "ALERT" "Giant phone crushing city" "Dismiss" "More"

Cueball with jetpack: "Wheeeee!"

Cueball to Megan: "Do you ever look up at the night sky and think, "Wow, I bet those little white dots taste ''delicious!''"

Neighbor: "Why is my house on fire ''again?!''
Cueball: "Dunno"
Laser captioned: "Laser"

Person with Washington Monument: "Okay, let it drop!"
|(-13300,-3260)
|y
|y
|
| Y
| Contains a reference to Kerbal Space Program, whimsically referring to the launchpad as the Vehicle Disassembly Building.

Contains a figure in a cave saying "MMM SPIDERS HOMF NOMF", which refers to [[1268: Alternate Universe|Alternate Universe]] and may also be a reference to the [https://reallyreallyreallytrying.tumblr.com/post/40033025233/average-person-eats-3-spiders-a-year-factoid Spiders Georg] meme.
|-
|<code>sun</code>
|'''The Sun'''
| "The sun is governed by magnetohydrodynamics, or 'Magic' for short"

"My countertop!"

"This will make a good soup base"

"Can I touch it yet?" "No, be patient. It's still too hot. Give it another 20 or 30 billion years."

"It's okay. I'm wearing five layers of sunscreen."

TV Anchor: "The forecast for today is lots of sun"

"This should be enough sunscreen"
|(-14950, 12080)
|y
|
|
|
|Difficult to escape from if you hit the core.
|-
|
|Sun's core
| Cueball: "The core of the sun may seem hot, but it only produces about as much energy per volume as a lizard" Megan: "Wow. So how many lizards are there?" Cueball: "No-one knows."
|
|Y
|
|
|
|Difficult to escape from. Can be escaped by rotating around the sun until an escape-like velocity could be reached.
|-
|<code>soupiter</code>
|'''Soupiter'''
|"I think it's chicken noodle? Hard to tell."
|(-800, -9040)
|Y
|
|
|
|A model of the solar system filled with soup out to the orbit of Jupiter. As commented by Cueball, noodle soup.
|-
|<code>nojapan</code>
|'''Earth without Japan'''
|"Something is missing."
|(-7680, -5850)
|Y
|
|
|
|Earth, except it's missing japan.
|-
|<code>japanmoon</code>
|'''Just Japan'''
|
|(-5930, -5800)
|Y
|
|
|
|A moon with water surrounding... just Japan.
|-
|<code>pigeons</code>
|'''A blob labeled "Pigeons"'''
|
|(-9020, -2490)
|Y
|
|
|
|A reference to Chapter 6 of What If? 2, where it would take 1.6 x 10^25 pigeons to lift you and a chair up to the halfway point of Australia's Q1 skyscraper.
|-
|<code>enterprise</code>
|'''Starship Enterprise'''
|
|(2389, -60879)
|Y
|
|
|
|Star Trek reference: The Enterprise-C, yes 2344,commanded by Captain Garrett's. While defending a Klingon outpost, the weapons discharges resulted in the creation of a temporal rift, through which the badly damaged Enterprise drifted. In the comic, there is a large, invisible gravity distortion near the Enterprise-C
|-
|<code>qwantz</code>
|'''Dinosaur planet'''
|"Welcome... to Jurassic Park."
| (20403,-49559)
|
|
|Y
|
|An homage to [https://www.qwantz.com/ Dinosaur Comics], a webcomic Randall has mentioned several times before. All the dinosaurs on the planet are black-and-white versions of the clip art dinosaurs in that comic. Also references the Jurassic Park movies, with CEO John Hammond welcoming paleontologists Dr. Sattler and Dr. Grant to the planet. The long grass depicted is a plot point in later films.<br><br>It seems like crashing into this planet hard enough will let you dive into the core, but that only lets you out on the other side. Then the system seems to glitch and have the ship phase into and out of the planet.
|-
|
|'''What If? 1 scenario planet'''
|
|
|
|
|
|
|
|-
|<code>roads</code>
|'''Cat blocking traffic flowing through portals'''
|
|
|
|
|
|
|
|-
|<code>outside</code>
|'''Edge of the Universe'''
|"Welcome, traveler!" (found inside the edge of the bubble universe)
| ( 6081, 26138 )
|
|
|
|
|It looks like a planet labeled "edge of the universe". Outside the universe, so inside the "edge of the universe" planet, is another universe, the bubble universe, whose outside is labeled "edge of the bubble universe". Hidden entrance is between 10 and 11 'o clock. It is a reference to [[Bubble Universes]].
|-
|<code>roads</code>
|'''A tree larger than the planet it's growing on'''
|
|
|
|Y
|
|
|May be a reference to [[2: Petit Trees (sketch)|Petit Trees]]. More probably, a reference to ''The Little Prince'', a French children's novel about a traveler from a distant asteroid. In the novel, baobab trees are a serious threat to the Prince's home asteroid, as they are so large that their roots would engulf the asteroid entirely. Randall has alluded to The Little Prince numerous times before, especially in what-if articles.
|-
|<code>outside</code>
|'''Milliways'''
|
| in code: <code>[0,-14500]</code><br>in game: <code>[0,29000]</code>
|
|
|Y
|Y
|A reference to Milliways, the Restaurant at the End of the Universe from ''The Hitchhiker's Guide to the Galaxy''. On one side of the planet, Ponytail, Cueball, Megan, and other characters gather on the patio of the Milliways restaurant; on the other side, the Sojourner rover examines a rock.
|-
|<code>greatattractor</code>
|'''The Great Attractor'''
|
|(-596048, 247952)
|
|Y
|
|
|Beret Guy stands on the surface of a large ball labeled "The Great Attractor". The gravity is extremely strong (over 200 times that of the black holes), leading to various bugs and collision issues. It's a reference to [[Great Attractor]], in which Beret Guy is gravitationally attracted to the Great Attractor more strongly than usual.
|-
|<code>present</code>
|'''Present'''
|
"I didn't do any of my Christmas shopping yet because I was too busy drawing tiny planets."

"I'm done with my shopping! I got everyone What if? 2"

"...You got me my own book?"

"Yeah! I figured that since you wrote it, it must be right up your alley."

"It does make a good gift, though. You can get it at xkcd.com/whatif2"

"I got you this present!"

"Is it an angry bobcat?"

"It might not be."
|in code: <code>[22820,-18920]</code><br>in game: <code>[45640,37840]</code>
|
|Y
|
|
|The XKCD cast react to giving each other What if 2? as a present. Black Hat gives Cueball a "gift" which he claims "might not be a bobcat", a reference to [[A-Minus-Minus]] A quarter of the planet was missing on the release day, but it's fixed now.
|-
|<code>maw1</code>, <code>maw2</code>, ... <code>maw14</code>
|'''Black hole cluster'''
|
|
|
|
|
|
|A cluster of black holes with extremely high gravitational strength, set to the maximum of 2048. Not particularly easy to land on with multiple conflicting gravitational fields, but once landed on, rather difficult to escape. Likely a reference to the [https://starwars.fandom.com/wiki/Maw_Cluster Maw Cluster] in Star Wars.
|-
|<code>remnant</code>
|'''Remnant'''
|"All right, that's close enough"
"Oh no"

{{w|Walkin' on the Sun|"So don't delay, act now, supplies are running out"}}

"In 5 billion years, the Sun will run out of fuel and suffer gigennial burnout."

"The immense gravity of the sun's remnant means that this is the tallest possible skyscraper."
|(19620, 3800)
|
|
|
|
|A stellar remnant, with high gravity (making it difficult to escape, although it's possible to achieve escape velocity by flying sideways). Has various small landmarks, including a "skyscraper" and suspension bridge. There is a set of images of a rocket descending towards the planet, falling and then trying to escape by sledding.
|-
|<code>steerswoman</code>
|'''Steerswoman Planet'''
|"As a Steerswoman, I have to answer any question anyone asks me, or I'm expelled from the order."
"What's one question that you would be unwilling to answer?"
"Oh no."

"Handle this artifact with great care. It contains a magical wizard's potion which the ancients called 'trinitrotoluene'"
|(-35070,-2500)
|
|
|
|Y
|A reference to the Steerswoman series of books by Rosemary Kirstein. Includes a number of references to the series, including a group of people observing a small object orbiting the planet.

Trinitrotoluene is better known as {{w|TNT}}, a powerful explosive.
|-
|<code>peeler</code>
|'''Peeler'''
|
|(-9270, 620)
|Y
|
|
|
|A reference to the question posed by "What If 2: Lose Weight the Slow and Incredibly Difficult Way". A large potato peeler is seen removing the earth's crust.
|}

===Ships===
{|class="wikitable sortable"
|-
! Name
! Description
! Location
! Filename
! Image
|-
|Default
|The starting ship.
|It is possible to change back to this ship by collecting a dot located within the Black Hole cluster
|ship2
|
|-
| Tintin
|
| On the starting planet; can be obtained by collecting the cannonball in orbit
| ship-tintin
|
|-
| Figure
|Stick figure
|On Goodhart, atop the mountain up which Sisyphus is pushing his boulder.
|ship-figure
|
|-
| Soccer ball
| Soccer ball shaped ship
| On Earth, between two figures playing ball
|ship-soccer
|
|-
|Alternative Ship
|Slightly thicker version of default ship
|Only available by using console to change Comic.ship
|ship1
|}

==Data and Maps==

View the data that is embedded in the comic on [[2712: Gravity/Data|this page]].

Maps created by the Community:
*https://bacontime.github.io/xkcd2712 | A zoomable map of the universe with markers for all planets, coins and with the option to highlight secret passages
*https://www.reddit.com/r/xkcd/comments/zpe7bz/i_rendered_the_entire_what_if_2_universe_as_a/ | The whole universe rendered as one big image

==Hacks==
Various modes and hacks have been found or developed by the community, and can be activated by opening the Javascript Console (F12 [Or Command-Alt-I in most browsers under Mac OS X] to open Developer Tools, then Console tab) and writing corresponding commands.<br>
'''Click to expand:'''<br>

<div class="mw-collapsible mw-collapsed leftAlign" style="width:100%">
<br>
*'''Speedhack:''' <code>ship.engines = "warp"</code> - Speed hacking, sets speed to 1.4x. set to "standard" to reset to normal speed
*'''Teleport to planet:''' <code>[Comic.voyager.pos.x, Comic.voyager.pos.y] = Comic.planetRects.'''''origin'''''.slice(0,2)</code> - teleport near a planet, in this example near earth. You'll still have to fly a bit towards the nearest planet to reach it. Replace '''''origin''''' with the ID of the planet you want to go to, from the table above.
*'''Teleport to coordinate:''' <code>[Comic.voyager.pos.x, Comic.voyager.pos.y] = '''''[0, -2000]'''''</code> - teleport to an exact coordinate. <code>[0, -2000]</code> happens to take you to the starting area.
*'''Improved radar:''' <code>Comic.wayfinderFarDistance = Infinity</code> - make the direction of all objects visible. This can be hard to understand though.
*'''Chaos Mode:''' <code>ship.engines="infinite improbability drive"</code> - Seems to randomly teleports the ship. A reference to its namesake in Hitchhiker's Guide to the Galaxy.
*'''Insta Death:''' <code>ship.shields = false</code> - Kill the player if they land on a planet, the code never sets it to false, so it seems to be always true.
*'''No Clip:''' <code>noclip = true</code> - Enables noclip. Also disables gravity.
*'''Select ship:''' <code>Comic.ship = "ship-tintin"</code> - Select ship (use filename from list of ships)
*'''Autorotate:''' <code>Comic.cameraRotation = false</code> - View does not rotate with ship
*'''Goggles:''' <code>ze.goggles()</code> - returns a warning: "they do nothing!". This is a reference to Hoverboard, where ''ze.goggles()'' would give you the ability to see false walls. Which itself is most likely a reference to the Simpsons where Radioactive man complains that his safety goggles do nothing against a deluge of acid.
*'''Python:''' <code>python("import antigravity")</code> - reverses gravity, so the ship falls away from planets. A reference to [[353: Python|Python]]. Reset with <code>Comic.gravityConstant = 100</code>. Also a reference to 353: Python.
*'''Light Mode''' <code>("Comic.lightMode = true")</code> - inverts the color of the comic. reset with <code>("Comic.lightMode = false")</code>
</div>
<br>

==Trivia==
The objects in the mini-universe of this browser game are all at fixed positions and do not interact through gravity, however, the ship controlled by the player is affected by gravity. While this makes it technically a relatively easy integration problem (of the position of the player ship forward in time), the integrator used seems to be a relatively simple one - and certainly not a symplectic one, because it does not conserve angular momentum. This can be seen when one manages to get into orbit around some object, e.g. the core of the sun. The orbit slowly decays over time.

The logic for extending the landing legs and landing is rather simple. A ship can (normally) land if it is facing away from the surface it collides with, and if its momentum is more-or-less directed towards the surface. Once landing is triggered, the ship will rotate to face directly away from the celestial body it is on, regardless of how sloped the surface is. The only way to get into space again is to accelerate forwards, as neither turning nor accelerating backwards cancels the landed state. All of this can be abused to land on almost everything. To land on the underside of an object, simply point your ship away from the object and slowly accelerate backwards to counteract the force of gravity. Landing on the side of an object is more difficult, as ships cannot accelerate sideways. The first method is to accelerate backwards to launch yourself upwards and towards the object so that at the top of your arc you will collide with the object. Then, rotate your ship accordingly to land. Method two is to just repeatedly slam your back of your ship into the object until you land. Note that with any of these weird landing methods, your ship will turn to face away from the source of gravity and can clip into objects.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

Welcome!

To celebrate the world of what if? 2, here is your very own planet to explore!

Give someone the science question-and-answer book what if? 2 for Christmas:
xkcd.com/whatif2

{{comic discussion}}
[[Category:Space]]
[[Category:Book promotion]]
[[Category:Interactive comics]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Black Hat]]
[[Category:Bobcats]]

explain xkcd - User contributions [en]

2712: Gravity