explain xkcd - User contributions [en]

1958: Self-Driving Issues

2018-02-22T12:31:01Z

162.158.91.191:

{{comic
| number = 1958
| date = February 21, 2018
| title = Self-Driving Issues
| image = self_driving_issues.png
| titletext = If most people turn into murderers all of a sudden, we'll need to push out a firmware update or something.
}}

==Explanation==

[[Cueball]] explains being worried about {{w|autonomous car|autonomous cars}}, noting that it may be possible to fool the sensory systems of the vehicles. This is a common concern with AIs; since they think analytically and have little to no capability for abstract thought, they can be fooled by things a human would immediately realize is deceptive.

However, Cueball quickly assumes that his argument actually doesn't hold up when comparing AI drivers to human drivers, as both rely on the same guidance framework. Human drivers follow signs and road markings, and must obey the laws of the road just as an AI must. Therefore, an attack on the road infrastructure could impact both AIs and humans. However, humans and AIs are not equally vulnerable. For example, a fake sign or a fake child could appear to a human as an obvious fake but fool an AI. A creative attacker could put up a sign with CAPTCHA-like text that would be readable by humans but not by an AI.

Cueball further wonders why, in this case, nobody tries to fool human drivers as they might try to fool an AI, but [[White Hat]] and [[Megan]] point out the obvious sociological answer; that most {{w|Road traffic safety|road safety systems}} benefit from humans not actively trying to maliciously sabotage them simply to cause accidents.

The [[title text]] continues the line of reasoning, noting that if most people did suddenly become murderers, the AI might be needed to be upgraded in order to deal with the presumable increase in people trying to cause car crashes by fooling the AI - a somewhat narrowly-focused solution given that a world full of murderers would probably have many more problems than that. As Megan sees humans as a 'component' of the road safety system, it might also be suggesting a firmware update for the buggy people who have all become murderers, one that would fix their murderous ways. We are not currently at a point where we can create and apply firmware updates for people, however... unless you count {{w|psychiatry}}, {{w|cognitive behavioral therapy}}, {{w|hypnosis}}, {{w|mind-altering drugs}}, {{w|prison}}, {{w|CRISPR}}, etc.

==Transcript==
:[Cueball is speaking while standing alone in a slim panel.]
:Cueball: I worry about self-driving car safety features.

:[In a frame-less panel it turns out that Cueball is standing between White Hat and Megan, holding his arms out towards each of them, while he continues to speak.]
:Cueball: What's to stop someone from painting fake lines on the road, or dropping a cutout of a pedestrian onto a highway, to make cars swerve and crash?

:[Zoom in on Cueball's head as he continues to contemplate the situation holding a hand to his chin, while looking in White Hat's direction. Megan replies from off-panel behind him.]
:Cueball: Except... those things would also work on human drivers. What's stopping people '''''now? '''''
:Megan (off-panel): Yeah, causing car crashes isn't hard.

:[Zoom back out to show all three of them again.]
:White Hat: I guess it's just that most people aren't murderers?
:Cueball: Oh, right. I always forget.
:Megan: An underappreciated component of our road safety system.

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring White Hat]]
[[Category:Comics featuring Megan]]
[[Category:Self-driving cars]]

==Trivia==
The [[title text]] was published with a typo: "murderers" was misspelled as "muderers."

The theme of human fear and overreaction to the advent of more or less autonomous robots also features in [[1955: Robots]].

{{comic discussion}}

Talk:1952: Backpack Decisions

2018-02-08T10:22:01Z

162.158.91.191:

Great, now I can't decide how to write the transcript [[Special:Contributions/108.162.216.40|108.162.216.40]] 15:00, 7 February 2018 (UTC)

And I now want a new backpack. I'm fine with the one I have, but *I want a new one dammit!* But I can't decide which one [[User:Jdluk|Jdluk]] ([[User talk:Jdluk|talk]]) 15:08, 7 February 2018 (UTC)

The knapsack optimization problem is famous for being NP-hard ([[wikipedia:Knapsack problem|Knapsack problem]]). Seems to be an allusion to it. Sebastian --[[Special:Contributions/162.158.91.191|162.158.91.191]] 15:53, 7 February 2018 (UTC)
: Nope, see below. The knapsack problem is about optimizing the amount of stuff put into something, while Cueball goes through a [[wikipedia:buying decision process|buying decision process]]. [[Special:Contributions/162.158.114.100|162.158.114.100]] 17:49, 7 February 2018 (UTC)
:: But the buying decision process could be solved by a variation of the knapsack optimation problem: You can choose several features, but cannot combine all of them. The difficulty would be linear in the number of available backpacks (but this would/could be a very large number - for all the other listed items like car, phone, college, appartment, laptop there is less choice available and the decision can be made way faster) and nonlinear in the number of criteria. Sebastian --[[Special:Contributions/162.158.91.191|162.158.91.191]] 10:18, 8 February 2018 (UTC)

This comic is an illustration of the [[wikipedia:law of triviality|law of triviality]] aka the bike-shed effect. [[Special:Contributions/162.158.114.100|162.158.114.100]] 17:42, 7 February 2018 (UTC)

: I don't believe the bike-shed effect is related, since that would imply that he is focusing on unimportant issues instead of important ones. In this case, the problem is trying to satisfy a number of important needs that are not fully met by any one backpack, forcing him to decide which can be left unsatisfied by any particular backpack. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 18:59, 7 February 2018 (UTC)

:: Yes, you are right. I had the comparison chart in mind and incorrectly connected the dots here. The correct description of the situation is of course [[wikipedia:analysis paralysis|analysis paralysis]]. Snap decisions apparently aren't infallible, either. :P [[Special:Contributions/162.158.114.100|162.158.114.100]] 19:38, 7 February 2018 (UTC)

:: Now that you point out your reasoning, I can see where someone might think deciding on a backpack is less important than buying a car or picking a college, which is consistent with the bike-shed effect. You deserve points for thinking of it, even though I think it really is more important to Cueball in this case. In fact, I'm surprised that Cueball didn't have a laptop in hand, calculating a composite feature weighted score per backpack to totally geek things up! ;-) [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 22:05, 7 February 2018 (UTC)

The description completely identifies the author with his figure. Mixes them up. That's very bad form and impolite. --[[Special:Contributions/162.158.88.236|162.158.88.236]] 21:39, 7 February 2018 (UTC)
:: On top of that, it makes no sense. Nothing in this comic says anything about laptop choices. [[Special:Contributions/162.158.178.111|162.158.178.111]] 03:08, 8 February 2018 (UTC)
:::Agree. Removed that part and marked it as incomplete, again. [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 10:03, 8 February 2018 (UTC)

Talk:1952: Backpack Decisions

2018-02-08T10:18:23Z

162.158.91.191:

Great, now I can't decide how to write the transcript [[Special:Contributions/108.162.216.40|108.162.216.40]] 15:00, 7 February 2018 (UTC)

And I now want a new backpack. I'm fine with the one I have, but *I want a new one dammit!* But I can't decide which one [[User:Jdluk|Jdluk]] ([[User talk:Jdluk|talk]]) 15:08, 7 February 2018 (UTC)

The knapsack optimization problem is famous for being NP-hard ([[wikipedia:Knapsack problem|Knapsack problem]]). Seems to be an allusion to it. Sebastian --[[Special:Contributions/162.158.91.191|162.158.91.191]] 15:53, 7 February 2018 (UTC)
: Nope, see below. The knapsack problem is about optimizing the amount of stuff put into something, while Cueball goes through a [[wikipedia:buying decision process|buying decision process]]. [[Special:Contributions/162.158.114.100|162.158.114.100]] 17:49, 7 February 2018 (UTC)
:: But the buying decision process could be solved by a variation of the knapsack optimation problem: You can choose several features, but cannot combine all of them. The difficulty would be linear in the number of available backpacks (but this would/could be a very large number) and nonlinear in the number of criteria. Sebastian --[[Special:Contributions/162.158.91.191|162.158.91.191]] 10:18, 8 February 2018 (UTC)

This comic is an illustration of the [[wikipedia:law of triviality|law of triviality]] aka the bike-shed effect. [[Special:Contributions/162.158.114.100|162.158.114.100]] 17:42, 7 February 2018 (UTC)

: I don't believe the bike-shed effect is related, since that would imply that he is focusing on unimportant issues instead of important ones. In this case, the problem is trying to satisfy a number of important needs that are not fully met by any one backpack, forcing him to decide which can be left unsatisfied by any particular backpack. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 18:59, 7 February 2018 (UTC)

:: Yes, you are right. I had the comparison chart in mind and incorrectly connected the dots here. The correct description of the situation is of course [[wikipedia:analysis paralysis|analysis paralysis]]. Snap decisions apparently aren't infallible, either. :P [[Special:Contributions/162.158.114.100|162.158.114.100]] 19:38, 7 February 2018 (UTC)

:: Now that you point out your reasoning, I can see where someone might think deciding on a backpack is less important than buying a car or picking a college, which is consistent with the bike-shed effect. You deserve points for thinking of it, even though I think it really is more important to Cueball in this case. In fact, I'm surprised that Cueball didn't have a laptop in hand, calculating a composite feature weighted score per backpack to totally geek things up! ;-) [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 22:05, 7 February 2018 (UTC)

The description completely identifies the author with his figure. Mixes them up. That's very bad form and impolite. --[[Special:Contributions/162.158.88.236|162.158.88.236]] 21:39, 7 February 2018 (UTC)
:: On top of that, it makes no sense. Nothing in this comic says anything about laptop choices. [[Special:Contributions/162.158.178.111|162.158.178.111]] 03:08, 8 February 2018 (UTC)
:::Agree. Removed that part and marked it as incomplete, again. [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 10:03, 8 February 2018 (UTC)

Talk:1952: Backpack Decisions

2018-02-07T15:53:42Z

162.158.91.191:

576: Packages

2016-01-27T15:45:30Z

162.158.91.191: minor correction

{{comic
| number = 576
| date = May 1, 2009
| title = Packages
| image = packages.png
| titletext = Day six: 'The hell? Who mails a bobcat?'
}}

==Explanation==
[[Cueball]] wrote a script that searches online shopping sites for items that cost US$1 with free shipping. Because the script is programmed to use an account with a $365 balance, this script will buy one random item per day for a full year. [[Megan]] comments that Cueball might just end up with "lots of crap" but he replies that he might get something interesting.

Over five days the script orders a length of rubber hose, a ski mask, a bear trap, a map of {{w|The Pentagon}} and "lube" (sexual lubrication). This pattern prompts Cueball to stop the script out of fear of being placed on a FBI watch list; to a paranoid passerby, the purchased items make Cueball look like a terrorist who plans to kidnap and {{w|Rubber-hose cryptanalysis|torture}} federal employees. And also a pervert; such a contrast is considered funny.

In the title text a sixth item is sent, a {{w|bobcat}}. This may be connected with [[325: A-Minus-Minus]] where [[Black Hat]] delivered a bobcat instead of a chair.

==Transcript==
:[Cueball is sitting at his computer.]
:Cueball: I love getting packages.

:[Megan enters and Cueball turns towards her.]
:Cueball: I set up a script to search eBay et. al. for $1 items with free shipping.

:[Cueball comes home with a backpack on his back and find a package waiting for him on his doorstop.]
:Cueball: I gave it $365, so each day it can buy me something random.

:[Cueball, again sitting at his computer.]
:Megan (off-screen): What if you just end up with lots of crap?
:Cueball: I'll give it away.
:Cueball: But I'm sure I'll end up with some interesting stuff.

:[The next five panels have a caption in a black frame at the top. The caption is written first for each panel. In the first panel Cueball has unpacked a hose. The paper lies in tatters on the floor. Megan stands next to him.]
:Day 1: Length of rubber hose
:Cueball: Could be handy around the house.

:[Cueball stands with a black item and the torn paper it came in. Megan looks on.]
:Day 2: Ski mask
:Cueball: It's spring, but hey.

:[Cueball is standing alone with a bear trap and the box it came in on the floor.]
:Day 3: Bear trap
:Cueball: Huh.

:[Megan is back as Cueball looks at a piece of paper that came in an envelope.]
:Day 4: Tourist map of the Pentagon.
:Megan: Uh oh.

:[Cueball is standing alone with a tube in one hand and the box it came in in the other hand.]
:Day 5: Lube
:Cueball: I'm stopping this before I end up on every F.B.I. watch list ever.

==Trivia==
Someone has set up an [http://bobcatinabox.com/ actual service] inspired by this comic, which does exactly what this comic describes.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Bobcats]]

730: Circuit Diagram

2015-10-07T13:32:33Z

162.158.91.191: /* Explanation */

{{comic
| number = 730
| date = April 21, 2010
| title = Circuit Diagram
| image = circuit_diagram.png
| titletext = I just caught myself idly trying to work out what that resistor mass would actually be, and realized I had self-nerd-sniped.
}}

==Explanation==
Another fine example of [[356|nerd sniping]].
There are pieces of circuit diagrams, road maps, chemical diagrams, and other things all mixed in.
Explanations for each below!

{|class="wikitable table-padding left-align"
!Image Fragment
!width="130px" | Image Location
!Description
|-
{{circuit-diagram-part|X=19|Y=25|W=106|H=37|image=circuit_diagram-019-025-106-037-scale.png|text=A map scale. Lists kilometers and miles as equivalent. And makes the diagram many miles wide.}}
{{circuit-diagram-part|X=15|Y=62|W=40|H=85|image=circuit_diagram-015-062-040-085-antenna.png|text=An antenna. Typical of radio receivers or transmitters. Or the Turtle in LOGO programming language}}
{{circuit-diagram-part|X=53|Y=60|W=41|H=87|image=circuit_diagram-053-060-041-087-inductor.png|text=A coil or inductor. Normal, but unlabeled.}}
{{circuit-diagram-part|X=107|Y=86|W=85|H=93|image=circuit_diagram-107-086-085-093-cloverleaf.png|text=A {{w|cloverleaf interchange}} or junction is a feature of road networks that does not belong in a circuit diagram. Of course, other types of {{w|p–n junction|junction}} are important in electronics.
A cloverleaf junction has previously been used in comic: [[253: Highway Engineer Pranks]]}}
{{circuit-diagram-part|X=184|Y=12|W=87|H=63|image=circuit_diagram-184-012-087-063-battery.png|text=A battery. The voltage of square root of two is strange, but getting about 1.41412... volts is not unheard of. This could also indicate an [[wikipedia:Root_mean_square|RMS]] voltage. The marked polarity is also the reverse of what is implied by the symbol (where the larger terminal is positive).}}
{{circuit-diagram-part|X=187|Y=110|W=94|H=71|image=circuit_diagram-187-110-094-071-resister.png|text=A 120 ohm resistor is normal enough. "Or to taste" is odd for a circuit diagram and more like instructions from a recipe, e.g., "1 tbsp tomato purée, or to taste".}}
{{circuit-diagram-part|X=283|Y=50|W=90|H=63|image=circuit_diagram-283-050-090-063-switch.png|text=A normal switch, with a notation to glue it open. Reminiscent of the [http://catb.org/esr/jargon/html/magic-story.html MAGIC/MORE MAGIC] switch.}}
{{circuit-diagram-part|X=337|Y=101|W=69|H=64|image=circuit_diagram-337-101-069-064-transisitor.png|text=A bipolar PNP transistor, except that it has two emitters and no collector.}}
{{circuit-diagram-part|X=52|Y=141|W=79|H=107|image=circuit_diagram-052-141-079-107-compass-points.png|text=Compass points. A map feature, not a circuit feature.}}
{{circuit-diagram-part|X=415|Y=18|W=63|H=58|image=circuit_diagram-415-018-063-058-resister.png|text=A normal resistor, labeled with color code. Brown-Blue-Orange would be 16000 ohms. Resistor color codes are for reading the value on the physical device itself. They would not normally be shown on the circuit diagram, where it's much easier to just write the number, e.g. 16K.}}
{{circuit-diagram-part|X=517|Y=14|W=42|H=32|image=circuit_diagram-517-014-042-032-diode.png|text=A normal diode.}}
{{circuit-diagram-part|X=615|Y=55|W=73|H=74|image=circuit_diagram-615-055-073-074-666timer.png|text=A chip. The normal timer is a "{{w|555_timer_IC|555}}". "666" would be the number of the beast in [http://www.blueletterbible.org/Bible.cfm?b=Rev&c=13&v=18&t=KJV#18 Rev. 13:18]. The pin connected to "?" is the CTRL pin on a normal 555 timer, which would typically be connected to ground (via a decoupling capacitor) if used at all; the implication here seems to be that it would be connected directly to Hell itself.}}
{{circuit-diagram-part|X=632|Y=138|W=69|H=41|image=circuit_diagram-632-138-069-041-bat.png|text=A Batman logo.}}
{{circuit-diagram-part|X=650|Y=211|W=75|H=71|image=circuit_diagram-650-211-075-071-squirrel.png|text=A squirrel, or perhaps a wire bent into the shape of a squirrel. What it does as a circuit element is unclear. [[Category:Squirrels|Squirrels]] have also appeared in past and future xkcd comics.}}
{{circuit-diagram-part|X=606|Y=165|W=54|H=53|image=circuit_diagram-606-165-054-053-inductor.png|text=A coil or inductor, or a spring symbol in Physics force diagrams, probably the latter as it is labeled with an 11-kilogram mass.}}
{{circuit-diagram-part|X=538|Y=209|W=99|H=59|image=circuit_diagram-538-209-099-059-generator.png|text=A 240-volt AC generator (or other power source).}}
{{circuit-diagram-part|X=483|Y=186|W=111|H=103|image=circuit_diagram-483-186-111-103-shorted-generator.png|text=A shorting wire around a generator. The label reads "Omit this if you're a '''wimp.'''" If this wire is included, it will quickly melt - or worse.}}
{{circuit-diagram-part|X=419|Y=78|W=57|H=75|image=circuit_diagram-419-078-057-075-scarab-beetles.png|text=A jar of {{w|Scarabaeidae|scarab beetles}}.}}
{{circuit-diagram-part|X=482|Y=47|W=28|H=44|image=circuit_diagram-482-047-028-044-variable-resister.png|text=A variable resistor with center tap. Normally, there would be an arrowhead on the center tap.}}
{{circuit-diagram-part|X=507|Y=53|W=22|H=27|image=circuit_diagram-507-053-022-027-capacitor.png|text=A normal capacitor.}}
{{circuit-diagram-part|X=577|Y=318|W=96|H=62|image=circuit_diagram-577-318-096-062-magic.png|text="{{w|Magic Smoke}}" is the legendary stuff inside a chip that comes out when it fails.}}
{{circuit-diagram-part|X=669|Y=315|W=51|H=66|image=circuit_diagram-669-315-051-066-frayed-wires.png|text=Some frayed or dangling wires.}}
{{circuit-diagram-part|X=567|Y=392|W=58|H=48|image=circuit_diagram-567-392-058-048-buoy.png|text=An object which is either a float used in fishing, a {{w|Tippe top}}, or perhaps a {{w|Naval mine|mine}}.}}
{{circuit-diagram-part|X=458|Y=336|W=111|H=86|image=circuit_diagram-458-336-111-086-moral-rectifier.png|text=A {{w|Diode_bridge|bridge rectifier}}, which would normally turn alternating current at the top and bottom into direct current on the left and right. In this case, it is labeled as a "moral rectifier". This is presumably a play on the idea of moral rectitude – it makes your circuit more moral. Why this matters in a circuit is unclear.}}
{{circuit-diagram-part|X=423|Y=259|W=80|H=85|image=circuit_diagram-423-259-080-085-warm-front.png|text=This resembles both the schematic symbol for part of a transformer and the meteorological symbol for a warm front. A {{w|warm front}} is a feature on a {{w|Surface weather analysis|synoptic weather map}}.}}
{{circuit-diagram-part|X=190|Y=199|W=54|H=52|image=circuit_diagram-190-199-054-052-battery.png|text=A normal 50-volt battery.}}
{{circuit-diagram-part|X=173|Y=200|W=89|H=56|image=circuit_diagram-173-200-089-056-shorted-battery.png|text=A battery is grounded on both sides. Something will melt or burn out quickly, unless these are separate "earth ground"s, in which case the ground might get a bit cooked.}}
{{circuit-diagram-part|X=259|Y=198|W=174|H=25|image=circuit_diagram-259-198-174-025-pull-wire.png|text=Text reads "Pull this wire really tight". This kind of physical-property issue may indicate a high-frequency radio device. Or, given the absurdity of the context, it's a silly reference to a "high tension wire."}}
{{circuit-diagram-part|X=141|Y=211|W=41|H=91|image=circuit_diagram-141-211-041-091-3-8-inch.png|text=A specified 3/8-inch separation. This probably indicates a carefully controlled capacitance issue. Also contradicts the scale of the drawing, by which the distance shown would be about 0.8 miles or 0.8 km.}}
{{circuit-diagram-part|X=173|Y=309|W=92|H=59|image=circuit_diagram-173-309-092-059-eel.png|text=An {{w|electric eel}}. This may be an effective power source in the circuit, capable of producing a shock at up to 600 volts and 1 ampere of current (600 watts), but for less than 2 ms.}}
{{circuit-diagram-part|X=266|Y=307|W=35|H=41|image=circuit_diagram-266-307-035-041-resistor.png|text=A normal resistor.}}
{{circuit-diagram-part|X=222|Y=358|W=34|H=29|image=circuit_diagram-222-358-034-029-capacitor.png|text=A normal capacitor.}}
{{circuit-diagram-part|X=130|Y=335|W=44|H=40|image=circuit_diagram-130-335-044-040-resistor.png|text=A normal resistor, labeled "ë". This may be a play on {{w|e (mathematical constant)|Euler's Number}}, which doesn't normally have a {{w|tréma}} or an {{w|umlaut (linguistics)|umlaut}}. Alternatively instead of being an umlaut or tréma it may indicate the second {{w|derivative}} of e with respect to time in {{w|Newton's notation}}, in which case, as e is a constant, the resistance of this element is zero.}}
{{circuit-diagram-part|X=65|Y=249|W=61|H=92|image=circuit_diagram-065-249-061-092-blender.png|text=This appears to be a blender.{{Citation needed}}}}
{{circuit-diagram-part|X=20|Y=342|W=115|H=73|image=circuit_diagram-020-342-115-073-arduino.png|text=An {{w|arduino}}, labeled "Arduino, just for blog cred". May refer to the fact that inexpensive, easy-to-integrate single-board computers like the arduino, which have contributed to the rise of {{w|Maker_culture}}, are used and discussed frequently in that culture, and the use of one might impress readers. The comment implies that an arduino is not otherwise needed in this circuit, although it is necessarily hard to tell, given the other components of the circuit.}}
{{circuit-diagram-part|X=39|Y=423|W=118|H=82|image=circuit_diagram-039-423-118-082-meca.png|text=A chip labeled "Most expensive chip available". The small curve at the top is a part of the packaging designed to show its orientation.}}
{{circuit-diagram-part|X=159|Y=428|W=91|H=50|image=circuit_diagram-159-428-091-050-neck-strap.png|text=Labeled "Neck Strap". Perhaps a piece of torture equipment or indicating that the circuit is part of an {{w|electric chair}}? May also be a reference to the grounded wrist straps people working with electronics commonly wear, to prevent accidental static discharges from frying the circuitry.}}
{{circuit-diagram-part|X=147|Y=480|W=110|H=88|image=circuit_diagram-147-480-110-088-switch.png|text=A switch labeled "Hire someone to open and close switch real fast." Possibly meant to perform the function of an oscillator in a more hackish manner and the reason for the neck strap. Could also be a reference to {{w|Maxwell's Demon}}.}}
{{circuit-diagram-part|X=273|Y=498|W=61|H=64|image=circuit_diagram-273-498-061-064-resistor.png|text=A 5 ohm resistor labeled "(decoy)". One end is not attached to anything. Perhaps this indicates wishful thinking that electrons might be tricked into entering this part of the circuit despite the fact that there's nowhere for them to go?}}
{{circuit-diagram-part|X=307|Y=453|W=103|H=56|image=circuit_diagram-307-453-103-056-tongue.png|text=A pair of contacts, labeled "Touch Tongue Here". Could be referring to the practice of daring someone to touch their tongue to the contacts of a 9V battery.}}
{{circuit-diagram-part|X=301|Y=270|W=45|H=45|image=circuit_diagram-301-270-045-045-frown.png|text=A frowny-face. See the float/mine.}}
{{circuit-diagram-part|X=294|Y=311|W=128|H=124|image=circuit_diagram-294-311-128-124-IC.png|text=A small integrated circuit. The lower gate is an inverter, wired as a free-running oscillator. The upper gate is an XOR wired to act as either a free-running oscillator or a latch. Since the XOR will be slower than the inverter, the overall output of the upper gate is probably very chaotic. Two "input" wires are not connected at all. An additional wire is attached to the top with hot glue. This last wire probably acts to control static electricity and leakage.}}
{{circuit-diagram-part|X=302|Y=235|W=91|H=25|image=circuit_diagram-302-235-091-025-curve.png|text=A caution sign at a curve. Another road feature in the circuit. This is a play on the notion that 90-degree corners on printed circuit board traces can disrupt signal integrity.}}
{{circuit-diagram-part|X=401|Y=455|W=67|H=68|image=circuit_diagram-401-455-067-068-CH3.png|text=A {{w|methyl group}} (chemistry) attached to a corner. If the circuit were an organic chemical, it would be reasonable to find a number of these.}}
{{circuit-diagram-part|X=453|Y=167|W=43|H=93|image=circuit_diagram-453-167-043-093-baloon.png|text=A balloon, possibly blowing in a breeze.}}
{{circuit-diagram-part|X=572|Y=68|W=22|H=43|image=circuit_diagram-572-068-022-043-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=508|Y=96|W=42|H=20|image=circuit_diagram-508-096-042-020-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=534|Y=61|W=22|H=31|image=circuit_diagram-534-061-022-031-ground.png|text=A ground connection.}}
{{circuit-diagram-part|X=472|Y=49|W=134|H=140|image=circuit_diagram-472-049-134-140-solderr-blob.png|text=A solder blob covering a portion of the circuit. Normally, this would not be part of the circuit diagram, but a mistake in building the circuit.}}
{{circuit-diagram-part|X=493|Y=443|W=207|H=158|image=circuit_diagram-493-443-207-158-res-rats-nest.png|text=A rats nest of 1 ohm resistors. It is labeled "Oh, so you think you're such a whiz at EE201?" The name EE201 (Electrical Engineering 201) follows US course naming conventions for what appears to be a basic level course in electrical engineering (compare the term {{w|101 (term)|101}}), which would include being taught how to [http://www.wikihow.com/Calculate-Series-and-Parallel-Resistance calculate the effective resistance of various resistor networks]. Performing the calculation on a network this complex would probably be extremely difficult. It appears to work out to 0.75800964845 ohms.}}
{{circuit-diagram-part|X=315|Y=533|W=232|H=200|image=circuit_diagram-362-531-151-167-arena.png|text=An arena, with a few bodies in it. Note the direction of movement enforced by the surrounding diodes, {{w|Mad_Max_Beyond_Thunderdome|"two men enter, one man leaves"}}, a film reference.}}
{{circuit-diagram-part|X=569|Y=653|W=47|H=51|image=circuit_diagram-569-653-047-051-resistor.png|text=A "{{w|pi}}" ohm resistor.}}
{{circuit-diagram-part|X=610|Y=655|W=75|H=70|image=circuit_diagram-610-655-075-070-generator.png|text=A 500-volt AC generator. The wiring to the right shorts out this generator.}}
{{circuit-diagram-part|X=481|Y=682|W=85|H=64|image=circuit_diagram-481-682-085-064-ground.png|text=A ground connection, labeled "Bury deep, but not too deep". This type of ground connection is called an "earth ground" The "too deep" part might be a reference to {{w|Moria (Middle-earth)|Moria}} in Lord of Rings. The dwarves dug too deeply and disturbed a balrog. See also comic [[760]].}}
{{circuit-diagram-part|X=17|Y=610|W=75|H=73|image=circuit_diagram-017-610-075-073-fishhook.png|text=A ground connection at the end of a curve, looking like a fishhook. Means perhaps "earthed down under", i.e., Australia or the southern hemisphere.}}
{{circuit-diagram-part|X=206|Y=662|W=66|H=45|image=circuit_diagram-206-662-066-045-yarn.png|text=A length of "wire" is labeled "yarn". This probably makes it a terrible conductor.}}
{{circuit-diagram-part|X=102|Y=590|W=93|H=88|image=circuit_diagram-102-590-093-088-fluxcapacitor.png|text=The {{w|DeLorean time machine#Flux capacitor|flux capacitor}} from {{w|Back to the Future}}.}}
{{circuit-diagram-part|X=138|Y=685|W=54|H=24|image=circuit_diagram-138-685-054-024-I95.png|text=A road sign for "I-95". Interstate 95 is the main north-south highway on the east coast of the United States, running from Maine to Florida.}}
{{circuit-diagram-part|X=12|Y=713|W=134|H=36|image=circuit_diagram-012-713-134-036-tothesun.png|text=A connection labeled "To center of Sun". A 93-million-mile circuit is rather large, but...}}
{{circuit-diagram-part|X=31|Y=753|W=144|H=177|image=circuit_diagram-031-753-144-177-rats-nest.png|text=A rat's nest of wires. Everything winds up being connected.}}
{{circuit-diagram-part|X=22|Y=513|W=97|H=61|image=circuit_diagram-022-513-097-061-esf.png|text=A label reading "Electrons Single File". If this happens, the resistance in this section of wire would be rather high.}}
{{circuit-diagram-part|X=256|Y=619|W=29|H=39|image=circuit_diagram-256-619-029-039-ground.png|text=A ground connection.}}
{{circuit-diagram-part|X=589|Y=600|W=58|H=46|image=circuit_diagram-589-600-058-046-vibrator.png|text=A vibrator, which would be a motor with an off-center weight attached to it.}}
{{circuit-diagram-part|X=532|Y=779|W=74|H=52|image=circuit_diagram-532-779-074-052-motor.png|text=A motor, labeled "To Scale". This indicates that the physical size and shape of the motor must match the size of the parts around it, or is consistent with the specified scale of the drawing. }}
{{circuit-diagram-part|X=662|Y=822|W=73|H=109|image=circuit_diagram-662-822-073-109-holy-ground.png|text=A ground connection, in a beaker labeled "{{w|holy Water}}", possibly creating {{w|Holy ground (religion)|holy ground}}.}}
{{circuit-diagram-part|X=197|Y=740|W=48|H=55|image=circuit_diagram-197-740-048-055-speed.png|text=A sign indicating a speed limit of 55 MPH. This is a rather typical road sign, but inappropriate for a circuit diagram.}}
{{circuit-diagram-part|X=238|Y=706|W=100|H=116|image=circuit_diagram-238-706-100-116-flipflop.png|text=A pair of NOR gates wired as a SR (set-reset) {{w|Flip-flop (electronics)|flip-flop}}. The label reads "May use an actual sandal instead", which is a play on the meanings of the term "{{w|Flip-flops|flip-flop}}".}}
{{circuit-diagram-part|X=322|Y=708|W=70|H=54|image=circuit_diagram-322-708-070-054-holdingpen.png|text=Something that could be the side view of a fence, labeled "Holding Pen".}}
{{circuit-diagram-part|X=339|Y=777|W=42|H=49|image=circuit_diagram-339-777-042-049-knot.png|text=A simple overhand knot. Also looks like a pretzel, which would have pretty high resistance.}}
{{circuit-diagram-part|X=191|Y=889|W=149|H=33|image=circuit_diagram-191-889-149-033-ecg.png|text=This appears to be an {{w|Electrocardiography|electrocardiograph}} (ECG) trace, but not the sort that would be seen in a healthy person. If this were a real ECG trace, the absence of large, clear {{w|P wave (electrocardiography)|P waves}} might indicate {{w|Atrial Fibrillation|fine atrial fibrillation}}, but in some recording configurations, P waves are sometimes lost in the noise anyway. Additionally, without a time scale to tell us the ventricular heart rate, it is impossible to make a strong educated diagnosis of any hypothetical disease at all. If we assume it is atrial fibrillation, is not clear if Randall intended this, or if he is just not familiar with how a normal ECG should look.}}
{{circuit-diagram-part|X=223|Y=826|W=82|H=68|image=circuit_diagram-223-826-082-068-photodiode.png|text=A photodiode, labeled "Tear Collector". A photodiode is a light-sensing device.}}
{{circuit-diagram-part|X=373|Y=859|W=49|H=68|image=circuit_diagram-373-859-049-068-lamp.png|text=A lamp. This is not [http://electronicsclub.info/circuitsymbols.htm the symbol used in electrical circuits], but a drawing of a lightbulb.}}
{{circuit-diagram-part|X=450|Y=887|W=65|H=32|image=circuit_diagram-450-887-065-032-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=537|Y=847|W=120|H=72|image=circuit_diagram-537-847-120-072-inductor.png|text=A coil or inductor, labeled "Take off shirt while wiring this part. Ooh, yeah, I like that."}}
{{circuit-diagram-part|X=504|Y=860|W=34|H=41|image=circuit_diagram-504-860-034-041-resistor.png|text=A resistor labeled "?". Presumably this means the resistance is unknown.}}
{{circuit-diagram-part|X=459|Y=828|W=55|H=38|image=circuit_diagram-459-828-055-038-resistor.png|text=A resistor labeled "YES". Likely another improper unit - a reference to boolean values YES (TRUE) and NO (FALSE). Depending on the limits of a circuit, a resistor would still have a YES boolean value. Possibly indicating that this is a real resistor, as opposed to the one above it in the circuit, labeled "not a resistor."}}
{{circuit-diagram-part|X=389|Y=774|W=58|H=53|image=circuit_diagram-389-774-058-053-resistor.png|text=A resistor labeled "8 mm".}}
{{circuit-diagram-part|X=443|Y=747|W=93|H=84|image=circuit_diagram-443-747-093-084-resistor.png|text=A resistor labeled "Not a resistor; wire just does this". Apparently the wire is or must be physically bent into a zig-zag shape, which would not serve much useful purpose, or perhaps it reflects the fact that any wire has a certain (small) amount of resistance just by being a wire.}}
{{circuit-diagram-part|X=415|Y=863|W=82|H=24|image=circuit_diagram-415-863-082-024-unsure.png|text=A symbol for a feedthrough capacitor, labeled "3 Liters". Probable word-play on "capacity/capacitor." Also similar to the symbol for an orifice or flow restriction used on plumbing or hydraulic diagrams, in which case the "3 Liters" might mean 3 liters per minute or per second.}}
|}

==Transcript==
:See table.

==Trivia==

*This is one of the [[:Category:Footer comics|five footer comics]] linked at the bottom part of the {{xkcd}} website.

{{comic discussion}}
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[[Category:Footer comics]]
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