explain xkcd - User contributions [en]

Talk:516: Wood Chips

2017-11-21T18:04:45Z

172.68.54.88:

The wood chips may be a reference to the 1995 horror movie 'Seven' in which the killer fed wood chips to his victim. Also here the wood chips serve as a starting point for an elaborate scavenger hunt. [[User:MrKaizer|MrKaizer]] ([[User talk:MrKaizer|talk]]) 13:18, 30 May 2013 (UTC)

Near the end of the explanation is a reference to a test of the Shroud of Turin which "appeared to prove the cloth '''was''' medieval in origin (albeit not old enough to have been used by Jesus)." This should say "was medieval in origin and thus not old enough to have been used on the body of Jesus." "Medieval" refers to the Middle Ages, commonly reckoned to cover about 500 to 1500, or in some contexts 1100-1500. As it stands, using "albeit," this sentence is as logical as saying "This equation is relativistic '''BUT''' does not go back to Newton." [[Special:Contributions/172.68.54.88|172.68.54.88]] 18:04, 21 November 2017 (UTC)

1878: Earth Orbital Diagram

2017-08-19T14:05:42Z

172.68.54.88:

{{comic
| number = 1878
| date = August 18, 2017
| title = Earth Orbital Diagram
| image = earth_orbital_diagram.png
| titletext = You shouldn't look directly at a partial eclipse because of the damage that can be caused by improperly aligning the solar-lunar orbital plane with the orbital bones around your eye.
}}

==Explanation==
{{incomplete|Created by a BOT - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
This comic is the third consecutive comic published in the week before the {{w|solar eclipse}} occurring on Monday, {{w|Solar eclipse of August 21, 2017|August 21, 2017}} which is a total solar eclipse and visible in totality within a band across the {{w|contiguous United States}} from west to east. The other comics are [[1876: Eclipse Searches]] and [[1877: Eclipse Science]].

The comic claims that the reason that eclipses don't happen every month is simple to understand by looking at an orbital diagram. Ironically, the cartoon has so many parts and labels that it is far more difficult to understand than is implied. While the graph itself is based on {{w|Orbital elements|astronomical definitions}} all the labels are nonsense in this context. In effect, the comic is a parody of a common joke in which a person asks a scientist a question, the scientist begins by saying "It's really quite simple", then proceeds to give a very lengthy and highly technical explanation that non-scientists would not be expected to understand.

All of the labels in the diagram are complicated words or phrases. Some are related to orbital mechanics (e.g. "equinox" and "perihelion"), while others are wholly unrelated or even made up. Each label is nonsensical in its place in the diagram. Compare/contrast with the standard {{w|Kepler orbit|Kepler Orbit}} diagram.

The title text references warnings to not look directly into the sun, but parodies those warnings by referring to 'orbit', the anatomical term for the eye socket.

===Labels and Their Astronomical Meanings===

;Arctangent
*{{w|Arctangent}} is the inverse function of the tangent function of trigonometry. You can determine a non-right angle of a right triangle by taking the arctangent of the length of the opposite side divided by the length of the adjacent side.
*The angle shown in the comic has no astronomical meaning.

;Astral plane
*The {{w|Astral plane}} is a plane of existence in various esoteric theories. Also used in fictional fantasy context.
*The picture shows the {{w|Orbit_of_the_Moon|lunar orbital plane}}, the plane in which the Moon orbits the Earth, tilted about 5.1 degrees from the ecliptic.

;Declension
*{{w|Declension}} is the inflection of nouns in a language.
*In astronomy, the {{w|Declination|declination}} is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system. It is measured north or south of the celestial equator, like the geographical latitude on Earth. But in the picture the label is at the angle for the axial tilt of the Earth.

;Determinant of the date of Easter
*In Western Christianity {{w|Easter}} always falls on the first Sunday after the first astronomical full moon after the beginning of spring (equinox). Thus it is defined by a combination of a solar and a moon calendar. The position of that angle isn't that bad but it should be not more than 30 degrees (slightly more than one month.)
*In mathematics, the determinant is a function of numerical matrices. In this context, however, it apparently refers to something that directly determines the date of Easter.

;Dimples of Venus
*The {{w|Dimples of Venus}} are indentations sometimes visible on the human lower back.
*In astronomy the {{w|Belt of Venus}} is a shadow cast by the Earth visible in its atmosphere.

;Enceliopsis
*{{w|Enceliopsis}} are small genus of flowering plants in the daisy family, appropriately known as "sunrays".
*In astronomy this point has also no specific meaning. But {{w|Enceladus}} is a moon around {{w|Saturn}}.

;Equinox / Solstice
{{w|Equinox}} and {{w|Solstice}} have very different meanings:
*An Equinox is one of two instants in the year when the sun is exactly over the equator; the length of day and night are very nearly equal that day at all locations on the planet, and (in the United States) it is the first day of Spring or Autumn, depending on the time of year.
*A Solstice is one of two instants in the year when the sun's angle is maximally far from Earth's equator; when one occurs, the length of the day or night is shortest or longest (depending on whether one is in the northern or southern hemisphere), and (in the United States) it marks the first day of summer or winter.

Both types occur because the Earth's rotation axis is tilted (at 23.4 degrees) from its orbital plane (ecliptic) about the Sun.

Jokingly insisting that two different terms are American/British variants of the same word has been the topic of [[1677: Contrails]].

;Hypothecate
*{{w|Hypothecate}} is a legal verb that means something similar to "make a mortgage".
*The depicted angle has no meaning, but a {{w|Hypotenuse}} is the longest side of a right-angled triangle. Here it is the shortest side on a non right-angled triangle.

;Obsequity
*Obsequity means the state of being obsequious (showing an indecorous willingness to obey or serve, or "sucking up").
*In astronomy the correct word is {{w|Obliquity}}, meaning an axial tilt.

;Perihelix
*This is a portmanteau of helix and perihelion.
*The {{w|perihelion}} is the point in a elliptical solar orbit that is closest to the Sun.

;Prolapse
*A {{w|Prolapse}} is a medical condition in which an internal organ is slipped forward or down.
*{{w|Retrograde and prograde motion}} are terms used to describe the apparent motion of celestial objects through the sky.

;Sagittal plane
*The {{w|Sagittal plane}} is an anatomical plane, dividing the body in left and right.
*The correct label in the picture would be the {{w|Ecliptic plane}}. The plane the Earth orbits the Sun.
*{{w|Sagittarius (constellation)|Sagittarius}} is one of the stellar constellations of the Zodiac. The center of the Milky Way lies in this constellation.

;Solar plexus
*The {{w|Solar plexus}} is a network of nerves located in the abdomen.
*{{w|Solar}} is an adjective referring to the Sun, the star in our solar system.

;Tropopause
*The {{w|Tropopause}} is the boundary in our atmosphere between the troposphere and stratosphere, defined as the boundary where air ceases to cool with increasing elevation. It is 9-17 km above sea level, not the thousands of kilometers as depicted here.

;Angle between the Astral and the Sagittal Planes
* The angle depicted is the inclination of the moon orbit. The planes are marked with greeks letter, the angle is marked with a symbol resembling the greek ''phi'' (ϕ).

;Errata
* Errata are corrections in a published text (e.g. a newspaper article) issued after the publication.
* The angle depicted as errata is half the angular size of the sun, which has to match the lunar angular size to cause a solar total eclipse.

==Explanation for "Why isn't there a (solar) eclipse every month?"==

If the plane of where the Earth orbits the Sun and where the Moon orbits the Earth were completely aligned, then there would be a solar eclipse at every new moon (once every {{w|Orbit_of_the_Moon#Lunar_periods| 29.5 days}}) and a lunar eclipse at every full moon (half a lunar period about 14.7 days after a New Moon). However, the plane in which the Moon orbits the Earth is tilted with an inclination of 5 degrees relative to that of the ecliptic plane (the plane defined by the Earth's orbit around the Sun). Eclipses are only possible during two eclipse seasons each year (half a year apart) where for a period of 31 to 37 days the Sun is nearly aligned with the two points in the tilted Earth-Moon plane where the Moon crosses the ecliptic plane. During an eclipse season at the time of a new moon there will be solar eclipses visible from certain locations and during full moons there will be lunar eclipses.

[[Image:Eclipse_Diagram.jpg]]

The real explanation of eclipses is evident from this xkcd comic, but is labeled with a fictional character similar to a Greek phi but with two vertical lines; the remaining labels also do not contribute to this explanation and exist only to distract or misinform the reader.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[An orbital map of the Earth is shown. The Sun is in the center, the Earth is at the right bottom, and the Moon is left below the Earth.]
:'''Why isn't there an eclipse every month?'''
:This is a common question! The answer is made clear by a quick look at the Earth's orbital diagram:

:[Label Sun:]
:Solar plexus

:[Label on the Earth's plane:]
:Sagittal plane

:[Labels on Earth's orbit (beginning at the Earth counterclockwise):]
:Perihelix, Declension, Obsequity, Hypothecate, Enceliopsis, Equinox (''Solstice'' in British English)

:[Two angles in the plane are labeled as:]
:Determinant of the date of Easter, Arctangent

:[The plane of the Moon is pictured in a small angle to the Earth's plane and named Astral Plane. The angle is presented between two lines (Greek Nu or Gamma and a double Greek Chi) and identified by a "Game Of Thrones" 'O' (a character that looks similar to a Greek Phi but with two vertical lines).]
:[The labels at the Moon's path are:]
:Tropopause, Prolapse, Errata.

:[An arrow points to the Earth at the zero meridian on the equator. The label reads:]
:Dimples of Venus

{{comic discussion}}

[[Category:Astronomy]]

1807: Listening

2017-03-22T20:29:11Z

172.68.54.88: /* Trivia */

{{comic
| number = 1807
| date = March 6, 2017
| title = Listening
| image = listening.png
| titletext = Sure, you could just ask, but this also takes care of the host gift thing.
}}

==Explanation==
This comic depicts [[Cueball]] and [[Ponytail]] welcoming [[Black Hat]] and [[Danish]] to their house. Black Hat immediately talks to {{w|Amazon Alexa}} to order two tons of {{w|creamed corn}}. This would be quite expensive (around $10,000), and the hosts would be charged because it was ordered on their {{w|Amazon Echo}} device. It would also be a serious inconvenience, as the purchase would be quite bulky and useless, seeing as an average person would have very little use for two tons of creamed corn.{{Citation needed}}

The caption claims that this is an effort to find systems recording conversations, such as Alexa or {{w|Google Home}}, for the security of the ''guests'', so they aren't being monitored by an always-on listening device without their consent (at least not without any consequences). However, because Black Hat is the one coming up with this it's more likely his motives are on the sadistic side, and it's more likely a warning for the hosts to turn off any voice-activated systems before having guests come over, so that the guests don't take advantage of them. (It should also be noted that such purchasing services encourage the user to set up a PIN code to stem off such exploits.)

A concerned "visitor" may also want to test for voice-activated systems when near any persons carrying an iPhone or Android mobile device, because these are also always-on listening devices. "Hey Siri" and "Ok Google" voice activation use the same technology as "Alexa" and "Echo" detection.

The title text says that this takes care of the "host gift thing", referring to the custom where house guests make gift to the hosts. However, Black Hat is making the hosts pay for it, so it can be as expensive as he wants, thus making this yet another example of his being a [[classhole]], for more examples of this see the [[#Trivia|trivia]] below.

==Transcript==
:[Black Hat and Danish enter Cueball and Ponytail's house. They have hardly passed the door mat, with the door still open showing the road and another house outside.]
:Ponytail: Hello, welcome to our house!
:Black Hat: Thanks for inviting us!
:Black Hat: Alexa, order two tons of creamed corn.
:Black Hat: Alexa, confirm purchase.

:[Caption below the frame:]
:When visiting a new house, it's good to check whether they have an always-on device transmitting your conversations somewhere.

==Trivia==
*In a previous comic, [[1559: Driving]], Black Hat took also took advantage of a cutting-edge AI—there, a self-driving car—by making it drive across the country without its owner or any passenger. And already back in [[596: Latitude]] he took advantage (of course) of people who constantly kept programs running on their phones that could track their movements.
*Another comic about testing if someone is listening is [[525: I Know You're Listening]]. Just as Black Hat may just speak without knowing for sure that there is an active Alexa, Cueball in the old comic also just speak out in case there are someone listening. In that case it was addresses to real surveillance, but as can be seen, in the entries below, Alexa may just end up being used like that later.
*Usually Cueball is paired with [[Megan]], but since Black Hat's girlfriend Danish looks like Megan but with longer hair, this makes is sensible to choose Ponytail as Cueball's partner here. They were also partnered in the next comic [[1808: Hacking]].
*Assuming a standard can of 14.75 oz (418 g) and Black Hat's order was in short tons the order would consist of 4339 cans. Consuming one per day it would last for approx. twelve years. But it's doubtful that the expiry date would be that long.
*In a recent [http://www.npr.org/2016/12/31/507670072/amazon-echo-murder-case-renews-privacy-questions-prompted-by-our-digital-footprints court case] authorities believed that an Amazon Echo may have recorded the identity of a murder suspect, leading to a debate about the privacy and safety implications of such devices.
*Another recent [http://www.theverge.com/2017/1/7/14200210/amazon-alexa-tech-news-anchor-order-dollhouse event] resulted in Alexa ordering several people unwanted doll houses.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Danish]]
[[Category:Food]]

1809: xkcd Phone 5

2017-03-15T19:12:30Z

172.68.54.88: /* List of features */

{{comic
| number = 1809
| date = March 10, 2017
| title = xkcd Phone 5
| image = xkcd_phone_5.png
| titletext = The phone will be collected by the toll operators and mailed back to you within 4-6 weeks.
}}

==Explanation==
{{incomplete|Seems almost complete now!}}
This is the fifth entry in the ongoing [[:Category:xkcd Phones|xkcd Phone series]], and once again, the comic plays with many standard tech buzzwords and horribly misuses all of them, to create a phone that sounds impressive but self-evidently isn't to even the most ignorant customer. The previous comic in the series [[1707: xkcd Phone 4]] was released almost 8 months before this one.

The slogan beneath the phone, "We're trying to catch up to Apple but refuse to skip numbers", is a reference to inconsistent product numbering, such as {{w|Samsung}} releasing the {{w|Note 7}} after the {{w|Note 5}}, likely in an attempt to catch up to the numbering of either the {{w|iPhone}} or {{w|Galaxy S}} series, both of which were already at 7. Similarly, there was also no official ''iPhone 2''. But there is an [[xkcd Phone 2]] available. The trademark sign behind the word "numbers" probably indicates a reference to the {{w|Numbers (spreadsheet)|Apple spreadsheet app}} with the same name.

This phone seems to have a curved display. But the edges are curved down and not up, as they are on other curved phones.

The title text that says that the phone will be returned to you by the toll operators is a reference to E-ZPass partnership feature; see explanation in the table regarding that feature.

===List of features===

; Hook shot

: In ''{{w|The Legend of Zelda}}'' the [http://zelda.gamepedia.com/Hookshot Hookshot] is a recurring weapon/tool. It is a machine consisting of a chain and hook. When used, the chain extends and sends the hook which is attached to it. It is used to bring items to {{w|Link (The Legend of Zelda)|Link}} or bring Link closer to a goal (''Link'' is the name shared by the main protagonists, each possessing the Spirit of the Hero). Likely a reference to new video game ''{{w|The Legend of Zelda: Breath of the Wild}}'', which was released a week prior to this comic. In the comic the hook shot is shown as a small add on to the phones top.

; Bluetooth speaker

: {{w|Bluetooth}} speakers are often used to play audio from a smartphone wirelessly, usually with more volume and better quality than the phone's small built-in speaker can provide. Embedding a bluetooth speaker into the phone would allow the phone to play audio from outside sources through its built-in speaker, which could be useful if no better speakers were available but would generally be avoided given the previously noted limitations of phone speakers. This is perhaps a jab at the current trend of playing music or Internet content audibly in public through the tiny, tinny speaker embedded in most phones. The Bluetooth speaker is located in the normal place for a phone's speaker.

; Stained-glass display

: {{w|Stained glass}} is colored glass, traditionally used for decorative windows in buildings most often churches. It is generally much thicker and because of the color much less transparent, especially for some colors, than the glass types normally used for touch-screens, making the phone difficult to use as it would remove some of the colors shown on the screen below the glass. A typical feature noticed about the glass for real phones would be its strength, as in work phones for construction workers.

; Gallium chassis remains solid up to 85°F

: Many high-end electronic devices have chassis made of alloys of light metals such as {{w|magnesium}} or {{w|titanium}} rather than {{w|steel}} or {{w|plastic}}. Besides being lightweight and of superior quality and durability than ordinary sheet steel or cheap plastic, these are often perceived as bragging points by the users, boasting about 'rare' metal chassis.

: {{w|Gallium}}, however, is an uncommon metal with a very low melting point of 85 °F (or 29.8 °C), making it one of only four pure metals (along with {{w|Mercury (element)|mercury}}, {{w|rubidium}} and {{w|caesium}}) that can be liquid around room temperature. Because the melting point is lower than the average {{w|human body temperature}} of 98.6 °F (37 °C) a gallium smartphone chassis would melt in the user's bare hand, assuming it hadn't already done so due to heat produced by its internal components. Even if the electronics had good heat management, cooling in smartphones is normally accomplished by distributing heat to the case, not exhausting it.

: A similar real advertisement regarding the chassis would be that it was {{w|waterproof}} down to some depth (say, 85 feet or 25 meters). See also the feature below regarding this.

; Soundproof

: A {{w|Soundproof}} chassis could result in the unwanted effect that the speakers and microphone may not work as no sound may enter or leave the phones chassis. A more likely feature would be waterproof (see above point).

; Can feel pain

: Possibly a reference to {{w|intelligent personal assistant|intelligent personal assistants}} like {{w|Siri}}, {{w|Cortana (software)|Cortana}} or {{w|Amazon Alexa|Alexa}} gaining consciousness (see [[1807: Listening]] for the latter). Such {{w|artificial intelligence}} references is a [[:Category:Artificial Intelligence|recurring subject]] on xkcd.

: This could mean that either the phone feels pain for damages inflicted upon it or it feels the user's pain level (regarding either physical and/or emotional pain). The meaning would quickly become apparent for the user if the chassis melts on contact with exposed skin leaving the phone with "open wounds".

: This could be seen as a similar feature of the first xkcd phone, [[1363: xkcd Phone]], where the title text notices (among many other things) that the ''phone will drown'' if submerged in water. A similar thing is also mentioned for [[1549: XKCD Phone 3]]. That phone is ''waterproof but can drown''. Since this phone is soundproof but not waterproof, per the two points above, the drowning issue may still be relevant. The second phone, [[1465: xkcd Phone 2]], ''cries when lost'' a similar display of emotions/feelings. That phone also mentions waterproofing, but here it is only the interior, and although it is washable, it is only a one-time feature (like the fold-ability of this one; see two points below). Finally it also [[1707: xkcd Phone 4]] mentions that it is waterproof, but not between 30-50 m down...

; E-ZPass partnership: Phone can be dropped into coin basket to pay tolls

: {{w|E-ZPass}} is an electronic toll collection system. The vehicle drives through the toll lane without stopping, and sensors detect the pass and deduct the appropriate amount from the user's account. The phone's integration with E-ZPass is absurd since the phone needs to be dropped into a coin basket to work. Not only would you have to stop in order to throw the phone into the coin basket, which defies the idea of E-ZPass, but you would also lose your phone.

: In the '''title text''', however, it says that the phone will be retrieved by the toll operators and returned by mail within 4–6 weeks. So this slightly mitigates the problem of losing the phone, but there would be about a month where the phone could not be used.

; Foldable (once)

: Almost anything long and slim can be "folded" by simply snapping it in half. But as it says, this can only be done once, because the phone cannot be unsnapped and will not work any more once it has been folded.

: This is a reference to the [http://www.digitaltrends.com/mobile/samsung-foldable-smartphone-news/ rumors of the new Samsung Galaxy X] that is really foldable like a piece of rubber. See [https://www.youtube.com/watch?v=fro_CNjxYwM this video].

: It could also refer to the fact that a version of iPhone had a weak spot that lead it to easily folding and breaking. And it could be a reference to {{w|Flip (form)|flip phones}}.

; Screen transfers images to skin

: Transferring images to the skin sounds like either real {{w|tattoos}} or the water tattoos used by children or other kinds of {{w|temporary tattoos}}. Likely it should be understood that it would be possible to transfer the image displayed on the screen to your skin, hopefully when activating the feature rather than by accident, and, preferably, also not permanently. This may also be a reference to the experimental Cicret Bracelet's ability to project images onto your arm: [http://www.snopes.com/photos/technology/cicret.asp]

; Retina storage

: This is a play on the name of Apple's prized "{{w|Retina Display}}". The joke may be in reference to Apple's possession of a trademark for the word "retina" in regards to computer equipment, which is made to seem absurd by the unusual use. It is not made clear whose retinas are meant to be stored. It could also be a reference to retinally implanted computers. The retina storage is a slot at the bottom of the phone right of the charging port.

; Background task automatically catches and eats Pokémon

: A reference to {{w|Pokémon Go}}, an augmented reality game where the goal is to go to specific locations and play a mini-game in order to catch virtual creatures called {{w|Pokémon}} (see [[1705: Pokémon Go]]). This phone apparently catches Pokémon automatically, similar to the external device {{w|Pokémon_Go#Pok.C3.A9mon_Go_Plus|Pokémon Go Plus}}. However, this feature also eats them, which is something that is not part of the game and wouldn't be desirable, as it is about collection and storing as many different Pokémon as possible. It could be a coincidence, but it seems funny that the label for this background feature is the only one that points at the back of the phone.

; Supercuts partnership: Trims hair fed into charging port

: {{w|Supercuts}} is an American hair salon chain that provides hair cuts and styling. The implication here is that the user can get a haircut by Supercuts by sticking hair into the charging slot. This is not only impractical and would only work for hair long enough to be fed into the port, but it would most likely result in a bad haircut. Also the slot would soon be filled with hair. The charging slot is otherwise placed in the normal spot and looks like a regular charging port.

: This feature could actually be quite dangerous if the hair is not removed from the charging slot afterwards because the hair could melt or catch fire inside the phone.

; Squelch knob

: {{w|Squelch}} is a feature of two-way radios (CB, ham, etc) which quiets background noise when no signal is present. For a smartphone, perhaps this knob could control the "signal-to-noise" ratio of your Facebook feed or other social media platforms. It takes the place of the headphone jack, replacing the normal hole with a small knob.

; IBM buckling-spring Home button

: {{w|IBM}} {{w|Buckling spring|buckling-spring}} keyboards are favorites of geeks for the feeling of quality and auditory feedback (keys click loudly when pressed) they provide. Real smartphones' home buttons, typically located exactly as in this image, provide little to no such satisfaction when pressed.

; Cot-caught merger switch

: This is a reference to the {{w|cot–caught merger}}, a linguistic change happening among English speakers, particularly in some parts of North America and the British Isles, which causes caught (previously pronounced "kawt") to be pronounced the same as cot (pronounced "kot"). The switch is clearly visible on the side of the phone. A real feature physically similar to this is the slide switch on the iPhone and iPad, allowing the user to (un)lock the orientation of the screen or to (un)mute the device.

; 60x optical zoom camera

: A powerful optical {{w|zoom lens}} is usually a desirable feature for cameras. However, as shown in the comic, it results in very bulky lens. If 60× zoom should be achieved the lens needs to be as big as shown on the backside of the phone, and the whole idea of being able to carry the smartphone easily in a pocket would be defied.

: For that reason, such lenses are never used in smartphones, although rarely some devices, like the {{w|Samsung Galaxy Camera}}, use a smaller lens with a similar design. But this is no longer a smartphone.

: This feature would seem to be a jab at the variety of add-on devices, including close-up lenses, handles, and external flashes, that are currently in use to enhance the phone's ability to function like a camera (and the {{w|selfie stick}}).

: Some phones might instead mention their {{w|digital zoom}} level instead. But that is not a popular feature among photo enthusiasts, as digital zooming gains no additional optical resolution. Users would actually be better off using the maximum optical zoom, and then enlarging their images with photo-editing software, which might offer better, but slower, algorithms (e.g. {{w|linear resampling}} versus {{w|Lanczos resampling}}). Likewise, (mobile phone) cameras are often advertised with their high number of {{w|megapixel}}s, while retaining their small {{w|image sensor size}}. As each individual sensor gets less light, it creates more {{w|image noise}}.

: Randall has made several comics about cameras before; see for instance [[1719: Superzoom]] and other comics linked via this.

: Contrast the [https://www.easy-macro.com EasyMacro] band - 4x zoom with little appreciable thickness.

: Assuming 60x is referring to the base focal length of the iPhone and that the xkcd Phone 5 has the same dimensions as the iPhone 7 Plus then in 35mm format this lens would be 30-1800mm f/0.4-f/24. This is a completely infeasible (but not physically impossible) lens in 35mm format, but similar small format lenses (albeit with more reasonable aperture ranges) do exist in mass production, for example the Nikon P900.

; LORAN navigation

: {{w|LORAN}} (Long Range Navigation) was a precursor to modern {{W|Global Positioning System|GPS}} navigation, using land-based transmitters. Once developed for sea shipping, it is accurate to about 300 meters (1,000 feet). The joke, of course, is that all modern smartphones have integrated GPS navigation which is far more accurate. Due to the much lower frequencies involved, reception of LORAN signals though is much better in areas with obstructed view of the sky. However {{w|LORAN#Commercial_use.2C_decommissioning|LORAN has been decommissioned}} more or less completely since before 2000.

: Incidentally, some receivers of the {{w|Decca Navigator System}} (which operates on a similar principle as LORAN) featured moving map displays, something we associate with modern GPS devices.

; 28-factor authentication

: An {{w|Authentication#Factors and identity|authentication factor}} is a way of proving one's identity. There are [http://www.nikacp.com/images/10.1.1.200.3888.pdf 3 generally recognized forms]: something you know, something you have, and something you are. It can be a password, a fingerprint, a physical key, etc.... Secure applications may include two or more factors; a common example is the "PIN and chip" system used with credit cards, where you need both the card and secret code to authorize a transaction. Many online services now provide two-factor authentication to protect against password-based attacks. 28-factor authentication would likely be very secure in theory but also so impractical that it would be unusable. The user will need to prove their identity 28 different ways which would be so time consuming that would outweigh the convenience of a smart phone.

==Transcript==
:[An image of a smartphone with a common optical camera lens attached on its back is shown. Over the entire length the case is slightly rounded. There are several features visible as bottom like features at the top and bottom of the front as well a microphone like slit at the top. A sliding switch is visible on the side, and at the bottom there is a knob, a connector port and a small slit. Clockwise starting from the top left all the labels read:]
:Hook shot
:Bluetooth speaker
:Stained-glass display
:Gallium chassis remains solid up to 85°F
:Soundproof
:Can feel pain
:E-ZPass partnership: Phone can be dropped into coin basket to pay tolls
:Foldable (once)
:Screen transfers images to skin
:Retina storage
:Background task automatically catches and eats Pokémon
:Supercuts partnership: Trims hair fed into charging port
:Squelch knob
:IBM buckling-spring home button
:Cot-caught merger switch
:60x optical zoom camera
:''LORAN'' navigation
:28-factor authentication

:[Below the phone:]
:Introducing
:<big>The</big> <big><big>xkcd Phone 5</big></big>
:''We're trying to catch up to Apple but refuse to skip numbers®TM''

{{comic discussion}}

[[Category:xkcd Phones]]
[[Category:Pokémon]]

1727: Number of Computers

2017-01-08T14:36:18Z

172.68.54.88: /* Explanation */ typo fix

{{comic
| number = 1727
| date = August 31, 2016
| title = Number of Computers
| image = number_of_computers.png
| titletext = They try to pad their numbers in the annual reports by counting Galileo's redundant systems as multiple computers, but they're falling behind badly either way.
}}

==Explanation==
This comic shows a {{w|semi-log plot}} with two red lines. The first line shows the increasing rate that {{w|computers}} have been created since the first came around in the 1940s. The graph shows this to occur around 1946. ({{w|Computer#First_computing_device|The precise date can be discussed}} but it was {{w|Computer#Digital_computers|around that time}} that the concept began to be applied to real working machines.) After the first computer, the number of computers created is shown to increase in a roughly straight line, indicating {{w|exponential growth}}. At the time of this comic's release in 2016, the curve has passed 10 billion computers, and its projection into the 2020s predicts that the number of computers will keep rising exponentially for at least 10 years to come.

The other plot on this graph represents all the computers destroyed by throwing them into {{w|Jupiter}}. So far this has only worked for the computers on two [[:Category:Space probes|space probes]]: those on the {{w|Galileo (spacecraft)|Galileo orbiter}} and its {{w|Galileo Probe|probe}}. The latter's mission was to fly into Jupiter so it went first in 1995; the orbiter went only after it had completed its mission in 2003. That constitutes the first two steps on the graph.

Recently the {{w|Juno (spacecraft)|Juno space probe}} entered into orbit (as only the second after Galileo), and that was celebrated with [[1703: Juno]] on xkcd. Juno's main mission has hardly begun yet; as at the time of this comic's release, it is not even in its final orbit. But once its mission is completed, it will also crash into Jupiter thus destroying a third computer. This is shown as the third step, but this section is shown with a dotted line, as the destruction may still fail if {{w|NASA}} loses contact with the probe before giving it the order to {{w|deorbit}} into Jupiter. This is scheduled to occur in 2018. All three steps on the graph fits with these years. (Note the number of computers created is not drawn with a dotted line into the future, probably because [[Randall]] believes this continued increase in numbers of computers to be quite certain over the next 10-20 years, whereas the outcome of a space probe mission is never certain, even when the probe is already in orbit and only 1½ years before scheduled deorbit!)

Space probes sent to Jupiter are typically scheduled to deorbit and fall into Jupiter's atmosphere. There can be several reasons for this, but one very important reason is to avoid {{w|Interplanetary contamination|contaminating}} {{w|Moons of Jupiter|Jupiter's moons}} with Earth {{w|pathogens}}, especially the four {{w|Galilean moons}} including {{w|Europa (moon)|Europa}} which {{w|Juno_(spacecraft)#Deorbit_and_disintegration|may harbor life}}. Also the huge [[681|gravity well]] of Jupiter that would have to be overcome for such a probe to leave the planet again makes it impossible to have an orbiting probe return to Earth with samples.

The caption below the comic humorously implies that NASA's reasons for causing the probes to deorbit into Jupiter is merely an attempt to destroy all the computers of the world. The caption notes that they are failing horribly, given that they have destroyed only three computers out of more than 10 billion. However, due to the semi-log scale, those three computers appear to have more significance than they actually have. The caption states that NASA really needs to pick up the pace (having only destroyed two since the 1940s, when computers were created), if they wish to actually finish the job of destroying all computers by hurling them into Jupiter. In addition, seeing as there have been many computers destroyed by other means, NASA will never actually catch up, no matter how hard they try, making this statistic even more irrelevant.

Destroying unwanted objects by hurling them into Jupiter pokes fun at the common science fiction trope of destroying objects by hurling them into the Sun [http://tvtropes.org/pmwiki/pmwiki.php/Main/HurlItIntoTheSun]. Hurling objects into the Sun is in fact extremely difficult because of the need to cancel out the orbital velocity of the earth. Randall may be referencing calculations ([https://qntm.org/destroy#sec3], see item 11) that show that hurling items into Jupiter requires 38% less energy than hurling them into the Sun.

The title text continues the caption by mentioning that in NASA's annual reports they try to make their numbers look better by counting the redundant computer systems on Galileo and its probe, thus doubling the numbers of destroyed computers to four. This of course makes no big difference given the exponential growth of computer production, which is also noted. This indicates that this is a top priority for NASA. That NASA might try to make themselves look better in a report by doubling a number could be realistic, presumably for political reasons or to get better funding.

==Transcript==
:[A graph with two red lines. The X-axis is a time-line with eight ticks with every second tick labeled below the axis, ranging from around 1940 to 2030. The Y-axis is a logarithmic count ranging from 1 to 1 billion. There are 12 ticks with the first and then every third tick after that larger than the two ticks in between. All the large ticks are labeled, but only the first two of the small ticks are similarly labeled. Labels are written to the left of the axis. All labels on both axes are written in gray. The first red line is a straight line (thus exponentially growing), starting close to the bottom left corner eventually reaching the upper right edge of the graph. The other red line begins around 1990 and has three straight steps. Each step is labeled with gray text, the last part of the line (after the present 2016), is dotted. Both of the red lines have an arrow pointing to them with a label above the arrow.]
:Left red line: Number of computers created
:Right red line: Number of computers destroyed by hurling them into Jupiter
:Labels on right red line:
::Galileo probe
::Galileo orbiter
::Juno (scheduled)
:Y-axis:
::1 billion
::1 million
::1,000
::100
::10
::1
:X-axis: 1960 1980 2000 2020

:[Caption below the panel:]
:NASA needs to pick up the pace if they ever want to finish the job.

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Line graphs]]
[[Category:Timelines]]
[[Category:Space probes]]
[[Category:Computers]]