explain xkcd - User contributions [en]

1452: Jurassic World

2014-11-26T12:32:07Z

Chronometry: /* Transcript */

{{comic
| number = 1452
| date = November 26, 2014
| title = Jurassic World
| image = jurassic_world.png
| titletext = Hey guys! What's eating you? Ha ha ha it's me! Oh, what fun we have.
}}

==Explanation==
This strip refers to ''[[wikipedia:Jurassic World|Jurassic World]]'', the new ''[[wikipedia:Jurassic Park|Jurassic Park]]'' movie. Megan doesn't feel that the T-Rex from the original movie can be improved upon, while White Hat insists they've created an even more terrifying, smarter T-Rex for this new movie. At one point White Hat says that for something "two decades old", art designers and modern computer graphics should be able to create something more convincing; Megan is about to object to the notion that T-Rexs are only 20 years old, setting up part of the punchline. In the final panel, White Hat introduces the new T-Rex, who is immediately recognizable as the T-Rex from Ryan North's ''[[wikipedia:Dinosaur Comics|Dinosaur Comics]]''. The joke is that ''Dinosaur Comics'''s T-Rex is about as far from smart and scary as it is possible for a T-Rex to be (as suggested by the alt text).

Characters from ''Dinosaur Comics'' also appeared in strips [[145:_Parody_Week:_Dinosaur_Comics|#145]] and [[1350:_Lorenz|#1350]].

==Transcript==
{{incomplete transcript}}
:White Hat: In ''Jurassic World'', we've used genetic engineering to create a ''better'' dinosaur.
:Megan: Tyrannosaurus is the most charismatic animal that ever lived, and you think you'll ''upstage'' it?

:White Hat: ''Tyrannosaurus'' was cool, but it's two decades old!
:Megan: I think it's a ''little'' older than that.

:White Hat: We took Tyrannosaurus and we ''improved'' it. Made it scarier, deadlier, smarter. Look - there it is!

:[White Hat and Megan stare up at T-Rex from ''Dinosaur Comics''.]

[[Category:Jurassic_Park]]
{{comic discussion}}

1441: Turnabout

2014-11-04T21:42:55Z

Chronometry: /* Transcript */

{{comic
| number = 1441
| date = October 31, 2014
| title = Turnabout
| image = turnabout.png
| titletext = Whenever I miss a shot with a sci-fi weapon, I say 'Apollo retroreflector' really fast, just in case.
}}

==Explanation==
In the comic, two people are engaging in a battle with laser guns. One appears to gain the upper hand as he jumps on an obstacle, as the other's shot goes wide. He delivers the classic line [http://tvtropes.org/pmwiki/pmwiki.php/Main/AnyLastWords "Any last words?"] and is answered with the confusing phrase "Apollo retroreflectors". The earlier wild shot, reflected off the Moon, promptly lances down from space and hits him in the back.

A {{w|retroreflector}} is a device or surface that reflects light back towards its source. Several such devices {{w|List_of_retroreflectors_on_the_Moon|were placed on the Moon}} and have been used ever since by scientists on Earth to {{w|Lunar Laser Ranging experiment|measure the distance between the two bodies using laser ranging}}.

The title text may be a reference to the common practice of "calling bank" in the game of basketball. In basketball, the backboard may be used to deflect the ball into the hoop. This is called a "bank shot." In casual games, if the player using the backboard in this way does not indicate that it was intentional (usually by "calling bank" before releasing the ball), the basket may not be counted in order to not give the player credit for a wild shot that happened to go in. When a player releases a shot that they realize is off the mark they sometimes quickly say "bank" to try and fool the other players into thinking that they were intentionally trying to "bank" the ball off the backboard into the hoop. In the title text scenario, "Apollo retroreflector" is used the same way "bank" is in basketball, i.e., the shooter meant to hit the target by reflection rather than directly.

[[Randall]] discussed the effect of hitting the Moon with lasers in [http://what-if.xkcd.com/13/ What If: Laser Pointer] and the likelihood of hitting a celestial object with a laser in [http://what-if.xkcd.com/109/ What If: Into the Blue].

Retroreflectors where placed by the American {{w|Apollo 11}}, {{w|Apollo 14|14}}, and {{w|Apollo 15|15}} missions. The Soviet {{w|Lunokhod 1}} and {{w|Lunokhod 2|2}} rovers also carried such reflectors; attempts to use them for laser ranging were unsuccessful from 1971 to 2010, but were successfully renewed after the rovers' positions were photographed by the {{w|Lunar Reconnaissance Orbiter}}.

The likelihood of the wild shot being aimed at the Moon is fairly low in itself, and the probability of accidentally hitting a retroreflector on the Moon is lower still. Even if it did, it is highly unlikely that a pistol-sized generator could produce a beam coherent enough to inflict damage after traveling to the Moon and back, as lasers built for the purpose of hitting retroreflectors on the Moon typically get a return around one quadrillionth of the original beam.

The title text claims you would need to say "Apollo retroreflector" really fast; this is an ambiguous reference (possibly on purpose) between 'calling bank' (which would have to be done quickly before the shot lands, since from Earth you would only have about [http://www.wolframalpha.com/input/?i=2+*+moon+distance+from+earth+%2F+speed+of+light 2.5 seconds] before the light is reflected back to its source) and giving a signal to aim the reflector in time to properly return the shot. In reality, in the latter case no instructors are possible; the reflector would need to be prepositioned, because the laser, at ''c'' can outrun any signal sent after firing, let alone comparatively slow sound waves that can't escape Earth's atmosphere at all.

==Transcript==
[Two people engage in battle using handheld laser guns.]

[The first shot by each person misses. Person 2 is ducking behind a block.]

[Person 1 jumps on top of the block. Person 2 fires upward and misses again.]

[Person 2 falls over backward as Person 1 aims his laser pistol.]
: Person 1: Any last words?
: Person 2: "Apollo retroreflectors".
: Person 1: What?

[A laser shot comes down from the sky and hits Person 1 in the back, knocking the pistol out of his hands.]

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Space]]

1431: Marriage

2014-10-08T06:21:04Z

Chronometry: /* Transcript */ Edits for clarity

{{comic
| number = 1431
| date = October 8, 2014
| title = Marriage
| image = marriage.png
| titletext = People often say that same-sex marriage now is like interracial marriage in the 60s. But in terms of public opinion, same-sex marriage now is like interracial marriage in the 90s, when it had already been legal nationwide for 30 years.
}}

==Explanation==
{{incomplete|Could probably use an explanation of the various shifts and dips of each population graph}}
Randall has compiled a graph of the percentage of Americans who approve of certain breakthroughs in marital freedom over time, and the percentage of Americans who live in states allowing those freedoms.

It shows that same-sex marriage was generally legalized after public opinion supported it, while interracial marriage was legalized before public opinion supported it.

This graph came soon after a ruling by the United States Supreme Court dismissed petitions aiming to review decisions by lower courts striking bans of same-sex marriages in several U.S. states.

==Transcript==
{{incomplete transcript}}
:[A graph with the x-axis showing time in years from 1940 to 2010. The y-axis shows percentage. The graph has 4 lines, 2 dotted and 2 solid, with 2 different colors. The first line from the top left, solid red, shows the percentage of people living in US states that legally allow interracial marriage. The second line, dotted red, shows popular acceptance of interracial marriage. The third line, dotted blue, shows popular acceptance of same sex couples. The last line, solid blue, shows the percentage of people living in US states that legally allow same sex marriages. All the lines show a general upward trend although only the solid red line reaches 100%.]

{{comic discussion}}

1422: My Phone is Dying

2014-09-17T06:40:40Z

Chronometry: /* Transcript */

{{comic
| number = 1422
| date = September 17, 2014
| title = My Phone is Dying
| image = my_phone_is_dying.png
| titletext = When it explodes, it will cast off its outer layers, leaving behind nothing but a slowly fading PalmPilot, calculator, or two-way pager.
}}

==Explanation==
Beret Guy's phone is about to "die". Cueball assumes this just means that the battery is running out and it needs to be recharged, but the phone in question appears to "die" in a way analogous to the {{w|Stellar_evolution|life and death}} of a star: expending its fuel while heating up and expanding before ultimately losing its outer layers and becoming a white dwarf or similar "lesser" star. Stars constantly undergo fusion reactions. The pressure generated by these reactions counteracts gravity from collapsing the star during the main lifespan of the star. As the hydrogen mostly fuses into helium in the core, the core gradually becomes more dense and the region of fusion gradually moves away from the center. Then, the star grows in size, reaching the stage of the Red Giant. Then, most of the "fuel" for fusion will be consumed, and gravity will collapse the star into a white dwarf while outer layers are shed. For stars much more massive than the sun, there will be a supernovae explosion caused by a violent collapse, which is very powerful. Because heavier stars often have shorter lifespans while producing more energy, Beret Guy probably references this when he refuses the charger. Both the supernova explosion and the collapse of red giants into white dwarfs shed their outer layers, which is referenced in the title text. Once extra mass is added to the dying star, analogous to "charging", the process only accelerates. The phone seems to have an certain mass - because [[White Hat]] expects the phone to go {{w|Supernova|(super)nova}}. Charging the phone may lead to a {{w|Nova|type 1a nova}}.
The comic also plays on the release of two new {{w|IPhone|iPhone models}} with {{w|IPhone_6|bigger}} screens, planned for 2 days after the release of the comic.

==Transcript==
[Beret Guy walks on-panel, carrying a smartphone]
: Beret Guy: My phone's about to die.
[The phone is now slightly larger, about the length of Beret Guy's arm]
: Cueball: Where'd you get a big iPhone? I didn't think they were out yet.
: Beret Guy: It's my regular one. It's just dying.
[The phone increases in size again. Beret Guy now holds it in both hands]
: Beret Guy: As it consumes its battery, it heats up and expands. Soon it will swell to enormous size, engulfing us both.
[The phone is now the size of Beret Guy's torso. Cueball is pointing off-panel]
: Beret Guy: Then it will collapse in a violent explosion!
: Cueball: ...do you want to borrow my charger?
: Beret Guy: That would only make it run out ''faster''!
{{comic discussion}}