explain xkcd - User contributions [en]

2115: Plutonium

2019-03-11T22:00:11Z

103.22.200.240: /* Explanation */ "gamer" is just used for computer game players, but this is about games in general.

{{comic
| number = 2115
| date = February 22, 2019
| title = Plutonium
| image = plutonium.png
| titletext = It's like someone briefly joined the team running the universe, introduced their idea for a cool mechanic, then left, and now everyone is stuck pretending that this wildly unbalanced dynamic makes sense.
}}

==Explanation==
{{incomplete|Created by a POWER ORB. The title text has multiple explanations, use them all. Also, the game one has some inconsistencies. Do NOT delete this tag too soon.}}
This comic pokes fun at the properties of {{w|plutonium}}, claiming that it is so unrealistically powerful that it may as well be random science fiction jargon. Indeed, the ability for a metal to radiate energy sounds impossible (this comic leaves out the inherent dangers of highly radioactive material). This is reflected by Megan and Hairy treating Cueball's idea as a joke.

There are devices that need substantial electrical power over long time – in the order of decades – but local sources of energy are insufficient or unavailable, yet constructing a power line or resupplying them with some power source (like fuel, fresh chemical batteries etc.) is either impossible or overly costly. Such devices include maritime beacons and buoys, automatic weather and science stations located in remote areas, and – most importantly – deep space probes and some planetary probes or science packs. Probes sent beyond Jupiter cannot effectively rely on photovoltaic panels for energy, because the great distance to the Sun means that the amount of solar radiation per unit of area is very low, requiring impractically large (and thus heavy) panels to provide enough energy. Carrying a lot of fuel adds mass to the probe, making them more expensive to launch.

Instead, such devices usually use {{W|radioisotope thermoelectric generator}}s (RTGs). In an RTG the natural radioactive decay of some unstable isotope (such as {{w|plutonium-238}} or {{w|strontium-90}}) produces a lot of heat, which is then used to generate energy using {{W|thermopile}}s, which generate electricity directly from temperature differences using the {{W|thermoelectric effect}}. The key element of an RTG, a pellet of radioactive material such as plutonium dioxide, could be facetiously described as a "power orb" – a lump of a substance that gives out heat apparently out of nothing.

Plutonium-238 must be produced from uranium in a nuclear reactor. Unlike plutonium-239, the {{W|Alpha decay|alpha radiation}} emitted by plutonium-238 is relatively harmless, as it is quickly absorbed by surrounding material and turned to heat – but plutonium is still incredibly dangerous if it gets inside a human body unprotected. In pure form it produces a little more than half a watt of heat per gram, which slowly drops as the material decays to lead, emitting a quarter watt per gram after 100 years.

The title text references development of games. In this context, the word ''mechanics'' is a metaphor referring to the set of rules and interactions that govern the imaginary world of the game. The ''mechanics'' of a game define the deterministic or randomized functions of events and/or characters within the game, the outcomes of actions commanded by the players, and so on. This metaphor refers to the {{W|mechanics}} science, and how it describes behavior of physical objects in the real world; However, contrary to real-world mechanics which "just happen" and we only try to describe how things work, in {{W|game mechanics}} every single rule or interaction has to be explicitly defined. The game simulates (to a given extent) an actual world. Game rules do not need to mimic the real world closely and often don't for many reasons; This results in (intended or otherwise) inconsistencies, unexpected behavior or imbalance. Game players complain about “imbalance” when a particular rule, interaction or item present in the game (such as an extremely powerful magical artifact) gives a character exploiting it a great and unjustified advantage. A rule or strategy within a game is often called a ''mechanic'', meant as one particular rule (singular) out of the overall set of rules (game mechanic''s''). Inconsistencies and possible imbalances can lead to problematic game mechanics being unused or left unresolved, after the creator of those mechanics ceases their participation in the game or game development process.

==Transcript==

:[Megan, Hairy, Cueball, and Ponytail are talking.]
:Megan: How will we keep the spacecraft supplied with heat and electricity?
:Cueball: We could use a power orb. They give off thousands of watts 24/7.
:Megan: Huh? How do you recharge it?
:Cueball: You don't. It's just made of a metal that emits energy.
:Megan: OK, come on.
:Hairy: Can we please be serious here?

:[Caption below the panel:]
:For something that's real, plutonium is so unrealistic.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Space]]

Talk:983: Privacy

2019-02-13T23:31:42Z

103.22.200.240:

If your roommate's in a raid, he's not gonna turn around and notice you shacking up any time soon. World of Warcraft is serious business. '''[[User:Davidy22|Davidy22]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 06:55, 2 February 2013 (UTC)

Is the transcript the original one? [[Special:Contributions/108.162.216.45|108.162.216.45]] 21:51, 29 November 2013 (UTC)
:No, the name Cueball is never mentioned by Randall. But in general it is close to the original one at all.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 22:23, 29 November 2013 (UTC)

I don't see how the tour for visiting Nelson Mandela could be interpreted as suggesting that Nelson Mandela was in the rare book collection and the tour was going to visit him - that just seems ridiculous. It's pretty clear that Nelson Mandela's visiting the library. --[[Special:Contributions/199.27.130.143|199.27.130.143]] 13:38, 11 August 2014 (UTC)
:Agreed. I have fixed the entry to reflect the same. It's worth noting that you could have done it first, and explained your edit here. This is, after all, a wiki editable by anyone. [[User:Orazor|Orazor]] ([[User talk:Orazor|talk]]) 09:56, 12 August 2014 (UTC)

Is the fact that the roommate says Tuesday a joke on how long raids can last? That he can reply with a day of the week rather than a time? I think I have seen jokes about the lengths of raids in other places, but I'm not sure. [[User:Athang|Athang]] ([[User talk:Athang|talk]]) 21:43, 20 August 2014 (UTC)
: Well if it's WoW then Tuesday is reset and maintenance shutdown day (usually). -Pennpenn [[Special:Contributions/108.162.250.155|108.162.250.155]] 05:15, 13 February 2015 (UTC)

This is a larger idea, so I didn't want to add it without running it by people: Might it be that the visiting Nelson Mandela is a joke about the stereotypical priorities of college students? I.E. that Megan and Cueball are so engaged with the idea of hooking up that a visit from a notable figure is ignored. {{unsigned|Xkcdeal}}

At first, I thought the "other dorm" one was showing the roommate setting up a {{w|RAID}} array... [[User:Whoop whoop pull up|Whoop whoop pull up]] ([[User talk:Whoop whoop pull up|talk]]) 19:01, 28 April 2017 (UTC)

This is just applied Murphy's Law, isn't it? [[Special:Contributions/103.22.200.240|103.22.200.240]] 23:31, 13 February 2019 (UTC)

2106: Sharing Options

2019-02-02T02:13:53Z

103.22.200.240: Undo vandalism revision 168957 by 162.158.78.106 (talk)

{{comic
| number = 2106
| date = February 1, 2019
| title = Sharing Options
| image = sharing_options.png
| titletext = How about posts that are public, but every time a company accesses a bunch of them, the API makes their CEO's account click 'like' on one of them at random so you get a notification.
}}

==Explanation==
{{incomplete|Created by 300 or a billion BOTs. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
This comic is a satire of social media's presence in our lives and its vulnerabilities.

Randall, who might have never heard of the Facebook option to share with "friends of friends" as well, is making a point that there ought to be some option between sharing posts only with your friends and making them completely public. The title text shows that he would specifically like to know when corporations read his posts.

Randall might be interested in [https://www.scuttlebutt.nz/ scuttlebutt] or [https://secushare.org/ secushare].

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball floating in midair is communicating with a small floating screen that resembles a smartphone. Other people and clouds visible floating by in background.]
:Screen: Welcome to social media! When you put stuff here, you have two options: (1) You can make it available to a small set of 300 or so approved friends.
:Screen: Or (2) you can share permanent copies of it all with billions of people, including internet scammers, random predatory companies, and hostile governments.

:Cueball: Why would anyone pick option two?
:Screen: Two is the default.
:Cueball: Yikes.

:Cueball: So those are the only two options? There's nothing in in between?
:Screen: I don't understand. Like what?

:Cueball: I mean...there are numbers between 300 and a billion.
:Screen: Huh? Name one.
:Screen: ''Pretty'' sure I would have heard of those.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Social networking]]

2106: Sharing Options

2019-02-02T02:13:08Z

103.22.200.240: Undo vandalism revision 168956 by 162.158.78.106 (talk)

2094: Short Selling

2019-01-07T05:40:13Z

103.22.200.240: tried to clarify some terms

{{comic
| number = 2094
| date = January 4, 2019
| title = Short Selling
| image = short_selling.png
| titletext = "I'm selling all my analogies at auction tomorrow, and that witch over there will give you 20 beans if you promise on pain of death to win them for her." "What if SEVERAL people promised witches they'd win, creating some kind of a ... squeeze? Gosh, you could make a lot of–" "Don't be silly! That probably never happens."
}}

==Explanation==
{{incomplete|Created by a SHORT WITCH. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

{{w|Short (finance)|Shorting stocks}} (short selling stocks) is a stock market practice where someone takes a risk because they believe that a certain stock's price is going to drop. The risk-taker borrows stock from a stockbroker (a person with a license to buy and sell stocks on other peoples behalf on a stock exchange), and then sells the stock that they've just borrowed, keeping the money from the sale. They then owe that stock to the stockbroker. But the risk-taker believes that they will be able to buy the same stock back on the stockmarket later on at a lower price, and then give it to the stockbroker to replace what they borrowed. If everything goes according to plan, the risk-taker will walk away with a profit. Of course, if things don't go according to plan, the risk-taker winds up losing money, because they have to buy back the stock for more than they sold it.

Cueball asks Ponytail to explain shorting stocks. Ponytail starts out with a fairy tale story that falls apart almost before she even starts.

Her story appears to begin by mixing up the story of {{w|Rapunzel|Rapunzel}} with {{w|Jack and the Beanstalk|Jack and the Beanstalk}}.

In one version of {{w|Rapunzel|Rapunzel}} a Father breaks into a witches garden to steal the Rapunzel plant for his pregnant wife. The Witch catches him and agrees to let him go and not punish him in exchange for the child.

In one version of the "{{w|Jack and the Beanstalk|Jack and the Beanstalk}}" fairy tale story, Jack sells a cow for magic beans. His mother, thinking the beans are fake, is angry with Jack. Jack plants the beans and a magic beanstalk grows up into the clouds. Jack climbs the beanstalk and explores the land above the clouds. He finds the home of a cruel giant and proceeds to steal from the giant. The giant discovers the theft and chases Jack back down the beanstalk. Jack reaches the bottom of the beanstalk first and cuts the beanstalk down. The giant falls to his death, and Jack uses his stolen wealth to take care of himself and his mother.

The combination of the two stories is similar to the story from the musical "{{w|Into the Woods|Into the Woods}}," in which a Father sneaks into the Witch's garden to steal vegetables, then trades his soon to be born child for the vegetables, but also steals beans in the process.

Ponytail's version starts with a father (not Jack) selling a child he hasn't had yet to a witch. Like short selling, the father is selling something he doesn't own. But unlike short selling, the father is selling something that doesn't exist yet. The child is sold for five magic beans, and the father thinks he will make a profit as he believes the child will only be worth two beans/love once born. The debt comes due, but the value of the child is now 200 beans/love. This is actually closer to the concept of writing a call option. If the witch makes a call option on the child for five magic beans, she has the right, but not the obligation, to buy the child for five beans. If the child turns out to be worth less than that, she doesn't have to do anything, but if the child turns out to be worth more (like, say, 200 beans), she can buy the child for an extreme discount and sell it to some other person for 200 beans, making a profit of 195 beans. The father figures that the child will probably be worth less, so he willingly gives the witch the right to buy his firstborn for five beans, regardless of the child's actual market values.

The somewhat broken analogy breaks further when Ponytail says the father now is going to fight the witch instead of paying the witch with the child. There is no "fighting" if a short selling stock strategy fails. (Or if writing a call option fails) You simply lose money.

Our now definitely broken analogy breaks down even further (if possible) by sending the kid up the beanstalk to fight the giant - a giant that Ponytail says represents high interest rates. Interest rates have nothing to do with shorting stocks. (Technically they can, but the short seller would have / should have calculated that when determining if their investment strategy would work.)

Cueball comments that the analogy is rapidly losing its value to him. Ponytail fires back with the comment that he should have shorted her advice before asking for it, thus making a profit. The decreased helpfulness of her wisdom is analogous to the decreased value of a shorted stock price.

The title text is actually the most useful part of this comic when it comes to investment advice. The witch (the broker) is offering the father (short seller) 20 magic beans now if the father/short seller buys all of the analogies (stocks) later. However, multiple witches/stock brokers trick multiple people into this strategy. Since every father/seller now needs the same analogies/stocks, and multiple witches need the exact same complete set of analogies, a bidding war erupts and it's impossible to please all the witches. The "winner" pays a much higher price than expected (limiting how much of a win it really is). And the losers wind up either dead or enslaved (bankrupt).

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball and Ponytail are walking together, talking.]
:Cueball: I don't understand shorting stocks.
:Ponytail: It's like when you promise your firstborn to a witch for five magic beans.

:[Ponytail close up]
:Cueball (off-panel): Is that a common–
:Ponytail: She's a sucker, right? You know your awful kid will be worth one or two beans at ''best''.

:[Ponytail and Cueball stopped, facing each other]
:Ponytail: But then it turns out you ''love'' your kid, a love worth 200 beans! You can't afford that loss!
:Ponytail: There's only one way out:
:Ponytail: You gotta fight the witch.

:[Ponytail and Cueball stopped, facing each other]
:Ponytail: So you send your kid up the beanstalk to battle the giant, who represents interest rates.
:Cueball: This analogy is getting less helpful by the minute.
:Ponytail: If only you'd somehow shorted my wisdom before you asked.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]

1779: 2017

2017-01-04T14:42:06Z

103.22.200.240: /* Small correction */

{{comic
| number = 1779
| date = December 30, 2016
| title = 2017
| image = 2017.png
| titletext = Things are looking good for the eclipse--Nate Silver says Earth will almost definitely still have a moon in August.
}}

==Explanation==
In this [[:Category:New Year|New Year comic]], [[Cueball]] and [[Megan]] share some of their (or [[Randall|Randall's]]) thoughts about the ending 2016 and the new year 2017 (hence the title). 2016 was a year which many people eagerly awaited the end of because of its increased turmoil (terrorist attacks, controversial political events in numerous countries, among other the election of {{w|Donald Trump}} for president in the United States and Britain voting for {{w|Brexit}}) as well as the the deaths of an unusually large number of well-known and beloved celebrities (several of these died in the first few days after Christmas).

Instead of simply condemning 2016 as a terrible year and expecting 2017 to be significantly better, Megan observes that much of what made 2016 bad is the effect that it will have upon future years rather than the actual events themselves (for instance, a divisive {{w|United States presidential election, 2016|U.S. presidential election}} has caused significant controversy in 2016, but President-elect Donald Trump will actually take office and begin to affect the world — whether for better or for worse — in 2017). Megan specifically states that ''2016 was bad was because of the things it sent us into 2017 without.'' As it is known that Randall is a {{w|Hillary Clinton}} supporter (as shown in the [[1756: I'm With Her]] comic), an additional reading of that line could be that we are headed into 2017 "without" a Hillary Clinton presidency.

Cueball claims that they should still have hope for the future, but Megan states that people had claimed that many of the bad things that did happen in 2016, could not happen (for instance Trump and Brexit). And as these things did happen, she foresees even worse events occurring in 2017, that we did not even think would be possible.

However, Randall also offers a glimpse of hope in the last few panels when Cueball observes that, just as all of the bad things in 2016 were unexpected, good things in 2017 that are unexpected could also happen, which should make us less sure what good may come of 2017. As such, he argues that we should hold on to our hope even though things seem difficult right now.

As the conversation unfolds, Megan and Cueball encounter an uprooted tree and cross it like a balance beam. This is a visual metaphor; the dead tree represents the end of the old year, while the crossing represents the transition into the new year. This is similar to the magical toboggan from {{w|Calvin and Hobbes}} that serves as a metaphor for their conversations, mentioned in [[529: Sledding Discussion]] and [[409: Electric Skateboard (Double Comic)]].

In the last panel Cueball mentioned that 2017 will also have a cool {{w|solar eclipse|eclipse}}, going through the central parts of North America. This may also serve as a reminder that the Earth continues to spin on despite all of the human turmoil going on on its surface. This is literally true, as the eclipse Randall is excited about is caused by the orbits of three celestial bodies lining up just right (the Sun, the Earth, and the Moon).

Cueball then also notes that 2017 is a {{w|prime number}} and states that prime-numbered years (prime years) have always been good to him. He thus illustrates the positive attitude that people can choose to take in order to see all that which is good and to spread a little bit more cheerfulness, and Megan is ready to take this positive view, although she may not totally buy in to it. This could also be a pun referencing the saying "being in his prime years".

If Cueball represents Randall (born 1984) he has lived through the following prime years: 1987, 1993, 1997, 1999, 2003 and 2011. If they have all been good years for Cueball it seems unlikely that he represents Randall, since Randall's wife was diagnosed with cancer in June 2011. Of course they were also married that year, but it would not seem likely that he would consider it a good year. First during the just ending year 2016 could she have been declared free of cancer, as it takes a five year follow up after end of treatment before the disease is declared defeated. Of course, we do not know how old Cueball really is, how much thought he/Randall actually put into his seemingly off-the-cuff remark, or whether those years were actually good for Cueball. But Randall does like math and would likely always know when a year is a prime number.

The title text is a reference to {{w|Nate Silver}} who is well-known (in the United States) as an election polling analyst on {{w|FiveThirtyEight}}. His model allowed for a higher chance that Donald Trump would win the presidency compared to other similar models — though the fact that he still favored a Clinton win may be contributing to getting humor from the idea that he may be "wrong" again, and the Moon could possibly vanish in 2017, making the year definitely worse than 2016. (Earth and Moon are so close in the space order of things, that any event affecting Moon orbit seriously will almost certainly end our civilization too.) This is accentuated by the qualifier "almost definitely", which is of humorously low confidence for presenting a fact as certain as the Moon not somehow disappearing within the next year.

Randall previously mentioned his excitement for the {{w|Solar eclipse of August 21, 2017|2017 eclipse}} exactly three years earlier in [[1302: Year in Review]], where Megan complains about not having seen an aurora during 2013, and she really hopes they don't cancel the 2017 eclipse. So this comic is the second time Randall has expressed concern that he will miss the eclipse.

There have been three previous New Year's comics with only the year used as the title: [[998: 2012]] in 2012, [[1311: 2014]] in 2014 and [[1624: 2016]] in 2016. This is the first odd-numbered years (and thus of course the first prime year) using only the new year as the title. It is also the first that has such a depressive mood. This thus follows the trend of the other negative comics released after Trump's victory, the first being [[1761: Blame]] and the second being [[1773: Negativity]], which both refer to the negativity on the internet spawned by Trump's election (among other things).

==Transcript==
:[Cueball and Megan walking outdoors]
:Cueball: Can't wait for this stupid year to be over.

:[The two approach a fallen tree]
:Megan: I can. This year made the future scarier. So much of why 2016 was bad was because of the things it sent us into 2017 without.

:[Megan has hopped up onto the tree trunk and begins to walk along it]
:Cueball: You gotta have hope, though.
:Megan: You say that, but you also said all this awful stuff couldn't happen, and it did. You're as clueless as the rest of us.

:[Cueball also walks along the tree trunk as Megan stops and turns to look at him]
:Cueball: Well, if we're wrong about which bad things can happen, it's got to make us at least a ''little'' less sure about which good things can't.

:[Closeup of Megan hopping down from the tree]
:Megan: I guess.

:[A distant shot of Megan and Cueball walking along again]
:Cueball: Plus, 2017 has a cool eclipse in it.
:Megan: Ooh, yeah!
:Cueball: And it's prime. Prime years have always been good for me.
:Megan: Sure, I'll take it.

{{comic discussion}}

[[Category:New Year]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Nate Silver]]
[[Category:Comics sharing name|2017]]
[[Category:Astronomy]]
[[Category:Math]]