explain xkcd - User contributions [en]

1807: Listening

2017-06-22T19:52:09Z

JoJo: + :Category:Artificial Intelligence

{{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 give a 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 speaks out in case there is someone listening. In that case, it was addressed 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 it 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]]
[[Category:Artificial Intelligence]]

1430: Proteins

2016-11-26T14:31:12Z

JoJo: /* Explanation */ tyop

{{comic
| number = 1430
| date = October 6, 2014
| title = Proteins
| image = proteins.png
| titletext = Check it out--when I tug the C-terminal tail, the binding tunnel squeezes!
}}

==Explanation==
In this comic, [[Cueball]] is asking [[Megan]] what she does, to which she replies that she works on software to predict protein folding. There are many folding prediction software programs. Some of the most well known are {{w|Folding@Home}}, {{w|Rosetta@Home}} and {{w|FoldIt}}.

{{w|Protein folding}} is the process by which proteins, which are floppy, unstructured chains of {{w|amino acids}} when initially synthesized in a cell, assume a stable, functional shape. If the folding process does not complete, or completes incorrectly, the resulting protein can be inactive or even toxic to the body. Misfolded proteins are responsible for several {{w|neurodegenerative}} diseases, including {{w|Alzheimer's disease}}, {{w|amyotrophic lateral sclerosis}} (ALS), and {{w|Parkinson's disease}}, as well as some non-neurodegenerative diseases such as cardiac amyloidosis.

Cueball asks Megan why it is such a hard computational problem; Megan's response is to ask Cueball if he's ever {{w|Origami|folded paper}} to make a {{w|Crane (bird)|crane}}. When he responds in the affirmative, she then compares the problem of predicting protein folding to creating a ''living'' crane by the paper-folding process. The analogy is that a protein cannot just fold to a figurative representation of a bio-molecule, the way a paper crane superficially resembles a live crane; the protein must assume an exact, perfect fold in order to be functional.

{{w|Levinthal's paradox}} is a thought experiment, also constituting a self-reference in the theory of protein folding. In 1969, Cyrus Levinthal noted that, because of the very large number of degrees of freedom in an unfolded polypeptide chain, the molecule has an astronomical number of possible conformations. For example, a polypeptide of 100 {{w|Residue (chemistry)|residue}}s will have 99 peptide bonds, and therefore 198 different {{w|Dihedral angle|phi and psi bond angles}}. If each of these bond angles can be in one of three stable conformations, the protein may misfold into a maximum of 3198 different conformations (including any possible folding redundancy). Therefore, if a protein were to attain its correctly folded configuration by sequentially sampling all the possible conformations, it would require a time longer than the age of the universe to arrive at its correct native conformation. This is true even if conformations are sampled at rapid (nanosecond or picosecond) rates. The "paradox" is that most small proteins fold spontaneously on a millisecond or even microsecond time scale. This paradox is central to computational approaches to protein structure prediction.

As Cueball mentally turns over the hypothetical process of folding paper to make a living crane, he wonders if he is allowed to perhaps "cut" the paper to make more complicated folds available. Megan replies "if you can fold a Protease enzyme;" these are proteins whose job it is to break down (i.e. "cut") other proteins, often in very specific ways. In this manner, Protease enzymes are analogous to extremely specialized scissors, so Megan is effectively saying "You can make cuts if you can fold yourself a pair of scissors."

Of course, when trying to predict the folding trajectory in nature of a protein A, and one is allowed to make cuts during the process, one is making the assumption that the Protease that cut protein A is already folded and functional. In other words, making cuts while folding might actually make the process ''more'' complicated, not less, as now you have to consider how the cutting enzyme is folded, too.

In origami, purists [http://www.barf.cc/jeremy/origami/BOOK/essays/origami_purism/origami_purism.htm] considered it as cheating if you cut the paper or use more than one sheet of paper, which is why Cueball asked if he was 'allowed' to do such in the hypothetical exercise they are discussing.

The title text refers to the result of folding a flapping bird in origami. By pulling the tail, the head will move forward and down. However, since the joke is about folding proteins, this idea is extrapolated to include the folded proteins. The C-terminus (end of the protein chain), in this case analogous of the tail, if "pulled" would cause a created cavity or tunnel to squeeze, much like pulling a knot would do the same.

{{w|Folding@Home}} (F@H) is a distributed computing project which aims to simulate protein folding for research purposes. Rather than the traditional model of using a supercomputer for computation, the project uses idle processing power of a network of personal computers in order to achieve massive computing power. Individuals can join the project by installing the F@H software (there is also a web version that can be run using Google Chrome) and are then able to track their contribution to the project. Individual members may join together as a team, with leaderboards measuring team and individual contributions.

Note that most modern computers do not "waste" computing time as much as older ones. They dynamically reduce their clock speed and other power consumption at times of low usage. If you donate computer time, you are probably also donating a bit of money to the cause in the form of your electricity bill. Many people consider this to be more fun, convenient and efficient than donating via credit card.

==Transcript==
:[Cueball is talking with Megan.]
:Cueball: What do you do?
:Megan: I make software that predicts how proteins will fold.
:Cueball: Is that a hard problem?
:Megan: Someone may someday find a harder one.
:Cueball: Why is it so hard?
:Megan: Have you ever made a folded paper crane?
:Cueball: Yeah.
:Megan: Imagine figuring out the folds to make an actual ''living'' crane.
:Cueball: ...''just'' folds? Can I make cuts?
:Megan: If you can fold a protease enzyme.

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

1642: Gravitational Waves

2016-03-06T11:38:46Z

JoJo: Add Category:Physics because it's also about confirming general relativity

{{comic
| number = 1642
| date = February 11, 2016
| title = Gravitational Waves
| image = gravitational waves.png
| titletext = "That last LinkedIn request set a new record for the most energetic physical event ever observed. Maybe we should respond." "Nah."
}}

==Explanation==
[[Megan]], [[Cueball]], and [[Ponytail]] are observing the results from a {{w|gravitational wave detector}} (see [[#Gravitational waves|details below]]). This comic came out on the day that the first direct observation of gravitational waves was [http://www.nature.com/news/einstein-s-gravitational-waves-found-at-last-1.19361 publicly announced] on 2016-02-11. The {{w|Gravitational wave observation|actual event}} was recorded five months before on 2015-09-14, but it was not reported publicly before they were sure it was a real signal. It seems that [[Randall]] knew in advance about this announcement because this comic was published on a Thursday, not following the normal publish schedule, to coincide with the [https://www.theguardian.com/science/2016/feb/11/gravitational-waves-discovery-hailed-as-breakthrough-of-the-century announcement], and there were no other comic released Friday that week. (The altered schedule could be viewed as a meta-reference to the {{w|Time warp (science fiction)|warping}} of {{w|spacetime}}). This is the second time within a month that a new astronomical announcement (of something discovered months before the actual announcement) has resulted in a related comic. The first being [[1633: Possible Undiscovered Planets]].

From the patterns in the {{w|gravitational waves}} detected by this instrument, it might be possible to guess the nature of the event. (e.g. two bodies with dissimilar masses circling a fixed point, two bodies with equal mass circling each other, collision of two massive bodies, etc.) It might also be possible to triangulate the location of the event. Based on these two facts (the location and nature of the event) we might be able to determine which astronomical bodies caused this event (and the status of those bodies afterwards). Thus, it provides an additional medium to observe the universe in addition to {{w|telescopes}} observing all kinds of {{w|electromagnetic radiation}}. This new medium might enable us to observe properties that we couldn't observe with the rest of our observation instruments.

However, the scientists in this comic appear to be receiving more than the expected signals from {{w|black hole}} collisions, they also receive gravitational {{w|Messaging spam|spam messages}}, such as invitations from {{w|Linkedin}}, a {{w|Mortgage loan|mortgage}} offer, and an announcement of a social meet-up, rather than observing astronomical events. (See [[#Explanation of observed events |table below]]).

There is also a joke on the social meet-up's use of the word ''local group'' because the '{{w|Local Group}}' is also the technical name for the group of galaxies containing the {{w|Milky Way}}.

It is not clear if these so called "events" are causing gravitational waves to be generated or if something, perhaps an alien civilization, is encoding spam messages in gravitational waves. It is plausible that aliens are using gravity waves to encode their messages, as we do something similar with electromagnetic waves to encode and send our messages. However, it would take an extremely advanced civilization to achieve gravity wave encoding. It requires the controlling of orbits and oscillations of super-massive bodies like the Sun, or more likely bodies ten times more massive than it. For example, the first event detected, both in this comic and in real life, was a merger of two black holes of roughly 30 solar masses each.

The title text makes the speculation, that something is sending spam encoded in gravity waves, seem more plausible, as it follows up with a joke that the message senders have gone to such a length that they caused the most energetic event recorded ever (perhaps on the scale of a few {{w|supernovae}} or black hole collisions). One of the scientists is so impressed with this effort that he suggests that they actually post a reply, but one of the other person declines with a "''Nah''"! (As you should always do with spam, else you will just encourage the sender by making it clear that there actually is a receiver on this address).

In [[1365: Inflation]] gravitational waves are also mentioned.

===Gravitational waves===
A gravitational wave detector is a device used to measure gravitational waves, small distortions of spacetime that were first predicted by {{w|Albert Einstein}} in 1916. Gravitational waves are ripples in the spacetime fabric itself.

In layman terms, a gravitational wave is like moving a stone through water while partly submerged. It will cause waves on the surface of the water as it moves through it. These waves will spread away from the center of disturbance and as they move, they will cause the water molecules to oscillate around their mean positions. Similar waves are created in the space-time fabric when two celestial bodies interact with each other. If you concentrate on an area of the fabric far away from the point of disturbance, it can be observed that if the wave causes compression in one direction, it'll cause expansion of the fabric in the other. See [http://www.einstein-online.info/spotlights/gw_waves this page] for nice animations.

Note that anything with a mass will cause a gravitational wave. Just as waves created by small stones are tiny in comparison to waves created by huge rocks in water, the waves from humans moving around will be tiny compared to the waves created by celestial bodies. Also, the bigger the body, the stronger the wave and the farther away it can be detected. That is why we can only detect gravity waves from heavy bodies like black holes or neutron stars but not from us moving around.

Now, let's consider spacetime fabric as a thin rubber sheet. If you mark any two points on this sheet and stretch or compress it along the axis joining those two points, the relative positions of these points with respect to their neighboring points do not change, but the distance between them changes.

{{w|LIGO}} (Laser Interferometer Gravitational-Wave Observatory) is a large-scale physics experiment designed to detect this compression/expansion, and it was LIGO who discovered the signal that caused this comic.

Two facts need to be remembered to easily understand the experiment. First, the {{w|speed of light}} (c) is constant and the speed of an object is the distance moved divided by the time taken to travel that far. Second, gravitational waves cause opposite effects (compression and expansion) in directions perpendicular to each other. At LIGO, an experiment is set up where two perpendicular long tunnels are constructed with apparatus to emit and detect laser beams. The beam from a laser is split into these two tunnels. After going through the tunnel and back again a few times the beams are brought back together. The lengths of the tunnels are set up in such a way that, in the absence of gravity waves, destructive interference between the two combined beams causes them to cancel one another out, resulting in the detector observing zero light intensity. When the gravitational wave passes through earth, one of the tunnel is expected to expand while the other is expected to compress. Due to the difference in lengths, the destructive interference is incomplete and the detectors will be able to detect the presence of light. This observation can be concluded as "detection of the gravitational wave passing through".

==Explanation of observed events==
{| class="wikitable"
| | Event
| | Explanation
|-
| | Black hole merger in Carina (30 M☉, 30 M☉)
| |
Possibly legitimate result from the gravitational wave detector. M☉ means 1 {{w|Solar Mass}} (1.98892×1030 kg). So the statement means that {{w|Binary black hole|two black holes}}, each one 30 times more massive than our Sun were observed {{w|Stellar collision|merging}} in the {{w|Carina (constellation)|Carina constellation}}. This observation is similar to the one actually reported in the announcement on the day of this comic, were the two black holes had masses of 36 and 29 solar masses (with a uncertainty that meant they could have had masses as close as 32 and 30 solar masses vs the 30+30 in this event). Also the {{w|Gravitational_wave_observation#Location_of_the_event|location of the event}} matches with Carina. Although at present time it is not possible to pinpoint the location of the event (that will need more detectors spread out across Earth) they still manage to find out that it most likely originated in the {{w|Southern Celestial Hemisphere}}, which is also where the Carina constellation is located.
|-
| | Zorlax the Mighty would like to connect on Linkedin
| |
A typical LinkedIn request. As this may be a message encoded in gravitational waves, it either means that LinkedIn has now grown outside the Earth, or that the Zorlax person would like to contact Earth. Zorlax is likely a reference to a kid's television gameshow, based on time travel, [https://www.youtube.com/watch?v=PdGGL0OrmFs Zorlax and the Time Travellers]. The first sentence in the movie is: ''Four billions of years ago in the Earths core, destined to be the master of time he is the Mighty Zorlax''. It is likely someone with the power over time would be able to create gravitational waves at his own leisure.
|-
| | Black hole merger in Orion (20 M☉, 50 M☉)
| |
Again, a possibly legitimate observation from the gravitational wave detector. It detected a black hole merger of two bodies in the {{w|Orion (constellation)|Orion constellation}}. One of them is 20 times more massive than Sun, the other is 50 times more massive than the Sun. As Orion is located at the {{w|celestial equator}} and since the masses are far from the one announced on the day of this comic, this would then represent a possible 2nd event to be measured later.
|-
| | Mortgage offer from Triangulum Galaxy
| |
{{w|Triangulum Galaxy}}, also known as Pinwheel Galaxy, is a {{w|spiral galaxy}} approximately 3 million light-years from Earth. It is the third largest galaxy in the Local Group after the {{w|Andromeda Galaxy}} and the Milky Way, these three being the only spiral galaxies in the group. This is presumably an offer to extend a loan, with a house on Earth serving as collateral. However, unless we develop {{w|wormholes}} or {{w|faster-than-light}} travel technologies, it will be difficult to submit an application, even if the offer is legitimate.
|-
| | Zorlax the Mighty would like to connect on Linkedin
| |
Same person who sent us LinkedIn invite moments ago. This repeated request may imply that Zorlax is desperate, or may be a jab at LinkedIn's persistence in spamming users with unaccepted connections to view and/or accept them. According to the title text, this was the most energetic physical event ever observed; it may be that Zorlax is demonstrating his capabilities in the hopes that the request would be accepted.
|-
| | Meet lonely singles in the local group tonight!
| |
The space advertisers are using space-GeoIP technology on a galactic scale to send spam. A Local Group is the technical term for the group of nearby galaxies that also includes the Milky Way, our own galaxy. There are more than 54 galaxies and few other celestial objects in our local group. This Local Group along with several others form the {{w|Virgo Supercluster}}. It would seem that the advertiser is targeting ads to everyone in the Virgo Supercluster. However, finding "lonely singles" in the 54 galaxies within our local group might be easier said than done for humans here on Earth. Another joke is that human race has been trying to find not just "lonely singles" but any lifeforms beyond Earth for the past few decades and hasn't been able to find them successfully. It seems that gravitational wave detector in the cartoon helped with this mission as well. This kind of spam was previously featured in [[713: GeoIP]].
|}

==Transcript==
:[Cueball, with arms up, is standing behind Megan who has her hands at her mouth, and who in turn is standing behind Ponytail, who is sitting in front of a large computer console with a screen, a keyboard, and several items on the side (presumably lights and labels). Three wires lead away from the console out of the image to the right.]
:Megan: The gravitational wave detector works! For the first time, we can listen in on the signals carried by ripples in the fabric of space itself!

:[Larger panel with the same setting in the middle, but both Cueball and Megan have taken their arms down. More of the wires from the console can be seen to the right. The computer lists six events:]
:Computer: '''''Event:''''' Black hole merger in Carina (30 M☉, 30 M☉)
:Computer: '''''Event:''''' Zorlax the Mighty would like to connect on Linkedin
:Computer: '''''Event:''''' Black hole merger in Orion (20 M☉, 50 M☉)
:Computer: '''''Event:''''' Mortgage offer from Triangulum Galaxy
:Computer: '''''Event:''''' Zorlax the Mighty would like to connect on Linkedin
:Computer: '''''Event:''''' Meet lonely singles in the local group tonight!

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Astronomy]]
[[Category:Space]]
[[Category:Social networking]]
[[Category:Physics]]

638: The Search

2015-07-07T16:03:24Z

JoJo: cat += Exoplantes

{{comic
| number = 638
| date = September 18, 2009
| title = The Search
| image = the search.png
| titletext = I am so excited about the Kepler mission. This is the second most important thing our species has ever done, right behind developing the concept of delivery pizza.
}}

==Explanation==
This comic is a commentary on the search for extraterrestrial intelligence. The ants' dialogue describes the narrow scope of their search (a few tiles, and only looking for pheromone trails), and thus they conclude that there is no other intelligent life. The irony is that humanity does of course exist, but were simply not present in the kitchen at the time of search, nor do we communicate with ant pheromones. Similarly, our ability to search outer space for other life is limited to our ability to detect specific modes of communication (i.e. radio waves) and to the very limited area of space imposed by technological limitations on transportation, range, and sensitivity of our equipment.

The title text refers to the {{w|Kepler mission}} to discover {{w|Extrasolar planets}}. This mission has found more than 2,700 planet candidates that still have to be confirmed by other telescopes. So that's the difference to the ants. As of August 2013, two "reaction wheels" on Kepler have failed, causing NASA to change the mission, though it will still be looking for planets with its two remaining wheels.

The second part is a bait-and-switch joke; by calling the search for extrasolar planets "the second most important thing our species has ever done", it creates the expectation that the "first most important thing" will be a monumental breakthrough, such as for example the concept of language. Instead, the title text ends up just revealing that [[Randall]] likes having pizza delivered.

==Transcript==
:Ant: We've searched dozens of these floor tiles for several common types of pheromone trails.
:Ant: If there were intelligent life up there, we would have seen its messages by now.

:The world's first ant colony to achieve sentience calls off the search for us.

{{comic discussion}}

[[category:Exoplanets]]

Template:circuit-diagram-part

2015-06-20T14:32:54Z

JoJo: Use "×" instead of "x"

<includeonly>
! [[Image:{{{image}}}]]
| {{{W}}}×{{{H}}} @ {{{X}}},{{{Y}}}
| {{{text}}}
|-
</includeonly><noinclude>
This template is to simplify writing of page [[730: Circuit Diagram]].
It expands to one line of a table.
</noinclude>

730: Circuit Diagram

2015-06-20T14:31:37Z

JoJo: /* Explanation */ w: Umlaut, Tréma, π

{{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.}}
{{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}}?}}
{{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}}
[[Category:Physics]]
[[Category:Maps]]
[[Category:Footer comics]]
[[Category:Squirrels]]

812: Glass

2015-06-20T12:23:49Z

JoJo: /* Explanation */ "Resonance" in particle physics.

{{comic
| number = 812
| date = October 29, 2010
| title = Glass
| image = glass.png
| titletext = I read in this one article that the breaking of electroweak symmetry is the reason we have SOULS. This guy with a degree said so!
}}

==Explanation==
In the beginning of the comic, [[Megan]] is trying to break a wine glass like an opera singer. This is a rather famous trick where the vocalist sings at the resonant, or natural frequency of the glass and cause it to resonate more and more until it can no longer handle the stress and breaks - for more info, see the {{w|Mythbusters}} episode about the Earthquake Machine. If the resonant frequency of the glass is outside of the singer's range, then putting some water in the glass will lower its resonant frequency. This effect can be used to play different notes on the rim of a glass by varying the amount of water in it. For example, see this [http://www.youtube.com/watch?v=ULiNR-k4m70 video].

While Megan is trying to break the glass by hitting its resonant frequency, she is actually creating something new. This is similar to particle physics where a (new) particle can be identified by a {{w|Resonance_(particle_physics)|resonance}} peak in the differencial cross section of a scattering experiment: Known particles (represented by water in the comic) plus some very specific amout of energy (the pitch of Megan's voice) lead to the creation of a new particle, the Higgs boson (the blood).

The term "God Particle" was coined by 1993 by physicist {{w|Leon M. Lederman}} to describe the {{w|Higgs boson}} because it's "central to the state of physics today, so crucial to our final understanding of the structure of matter, yet so elusive." Many people misinterpret the name to be some kind of link between physics and religion, so physics is getting back at them by playing pranks that resemble famous miracles from Christian tradition:
*Jesus turned water into wine at the marriage in Cana.
*The first of the ten plagues in Egypt turned all of the water into blood — the rivers, canals, ponds, pools, and every sort of container holding water.
*The wine turning into blood is a reference to the Catholic ritual of {{w|Transubstantiation}}.

The title text refers to the fact that people would believe anything that comes from someone with a college degree, since the degree implies that he was highly educated, thus very knowledgeable.

==Transcript==
:[Megan is singing, Cueball is staring at a glass of water on a table.]
:Megan: EEEEEEEEEEEEEEEEEEEEEEEEEEE... Anything break?
:Cueball: No, but the water in the glass turned to wine.

:[Cueball picks up glass]
:Megan: Weird.
:Cueball: No, wait. This is blood.

:Megan: Okay, physics, quit fucking with us.
:Physics: You stop looking for the Higgs boson and we'll talk.

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