explain xkcd - User contributions [en]

Talk:2139: Email Settings

2019-04-23T10:19:20Z

162.158.150.76: undo

Character set: I read the choice to be between ASCII only and non-ASCII only. That is, if you select non-ASCII only then you have no ordinary English letters, no decimal digits, no ordinary punctuation. Rather minimally useful.
:: Non-unicode can show ordinary English letters, for example the group starting at U+FF0x, but an ASCII system will see it as binary garbage that will generate unexpected beeps, corrupt terminals, and crash old software. [[Special:Contributions/162.158.78.196|162.158.78.196]] 20:23, 19 April 2019 (UTC)

ASCII, '''OLD''' ASCII, which is characters 0-127, includes '''ONLY CAPS''', plus the common punctuation and whitespace. The lower case letters are all part of '''EXTENDED ASCII'''. So, limiting to old ASCII, is limiting to all-caps, and limiting to only the second half of ASCII is even worse, as it has all the lower case letters, but, not only no caps, but also no punctuation, whitespace, or numerals.
I'll leave it to someone with a login to make the correction.
:: {{w|ASCII}} 0-127 includes _both_ uppercase and lowercase. [[Special:Contributions/162.158.78.196|162.158.78.196]] 20:23, 19 April 2019 (UTC)

Show unread email count: Wording in the graphic is ambiguous for me. Does show unread email count on my projected day of death mean a) show, today, what will be the count on my projected day of death, or b) wait to show any count until the very day I will probably to die. Choice a is indeed probably depressing. Choice b is more of a pop-up surprise if you didn't know it was coming, saying Hey, buddy, here's your final score, well done. JohnB [[Special:Contributions/173.245.54.37|173.245.54.37]] 14:15, 19 April 2019 (UTC)
:: I interpreted the unread email count as you laid out in option "b," this could be a reference to the relatively new features of social networks which create "memorialized" profiles for members who died. This number would undoubtedly be like a memorial, provided you actually died on that day. If you didn't die it would be like a pop-up. It could also be a simple exaggeration of the statement that you'd rather not see your number, as seeing the number is depressing. [[Special:Contributions/172.69.70.59|172.69.70.59]] 15:24, 19 April 2019 (UTC) Sam

I was going to edit the page with specifics on when html e-mail came into use, because I was sure I was using/experimenting with html in e-mail as early as 20 years ago. But looking at the wikipedia page on the topic seems to suggest that the adoption was much sooner than that, but I can still remember using html when I was a teenager, so I'm not sure what's going on here... [[Special:Contributions/172.69.70.59|172.69.70.59]] 15:24, 19 April 2019 (UTC) Sam
::I certainly remember sending emails with HTML formatting back in the late 90's. IIRC, I was using Netscape Communicator(?) and it used html snippets in an otherwise ascii email. At my first job in the early oughts, I had to manage an email subscription list for a newsletter that used mime-encoded multipart html emails. Not all the subscribers could see the html part, and I think AOL users often got gibberish due to bad support for mime-encoded messages in the AOL email client. --[[Special:Contributions/172.68.46.77|172.68.46.77]] 16:00, 20 April 2019 (UTC)

Seems to be that since the first option says 'reply functionality' the option which says 'Forward to Address Book' does not allow you to type a reply. Rather than 'forwarding your reply to your address book' I believe this would simply forward the email to everyone in your address book. Make sense as a joke at the expense of people who just forward emails/email chains. [[Special:Contributions/172.69.44.144|172.69.44.144]] 16:26, 19 April 2019 (UTC)

Despite what the explanation currently indicates, "reply all" definitely means reply to all recipients of the original email. [[Special:Contributions/172.69.70.59|172.69.70.59]] 21:15, 19 April 2019 (UTC)

Any idea why the dialog uses a Right-to-Left (RTL) formatting? [[Special:Contributions/141.101.99.131|141.101.99.131]] 18:14, 21 April 2019 (UTC)
:Having the text right next to the radiobuttons/tickboxes makes it much easier to identify which button belongs to which setting.--[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 04:42, 22 April 2019 (UTC)
:I agree with the previous reply, but I think you mean "right-aligned" formatting instead of "RTL" formatting, which usually means the letters are actually ordered from right to left in reverse order. I don't think radio buttons are typically displayed on the right side of the label though. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 11:46, 22 April 2019 (UTC)

== Google and vacation ==

Google knows when you're on vacation by comparing your present cellphone GPS coordinates to your typical gps coordinates. They also always know your location via IP, to some extent. [[Special:Contributions/108.162.242.23|108.162.242.23]] 02:50, 21 April 2019 (UTC)
:That doesn't work necessarily, you could be on a work trip.[[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 17:35, 22 April 2019 (UTC)
::Don't forget that any of this technology is probably founded on Microsoft (doesn't)Works. [[Special:Contributions/103.22.200.120|103.22.200.120]] 02:19, 23 April 2019 (UTC)

Talk:2135: M87 Black Hole Size Comparison

2019-04-18T08:28:46Z

162.158.150.76:

inb4 anti-semitic troll vandalizes the page [[Special:Contributions/162.158.78.64|162.158.78.64]] 19:38, 10 April 2019 (UTC)
:Jeez, it hasn't happened yet? --[[User:Youforgotthisthing|Youforgotthisthing]] ([[User talk:Youforgotthisthing|talk]]) 19:54, 10 April 2019 (UTC)
::Shhh! You'll jinx it! [[User:Herobrine|Herobrine]] ([[User talk:Herobrine|talk]]) 21:07, 10 April 2019 (UTC)
::I’m surprised. [[User:Netherin5|“That Guy from the Netherlands”]] ([[User talk:Netherin5|talk]]) 23:06, 10 April 2019 (UTC)
::I always miss it, you guys are too fast for me to see it. Not that I want to see it of course. [[User:Linker|Linker]] ([[User talk:Linker|talk]]) 12:08, 11 April 2019 (UTC)
:Well, we made it until 15:40 on the 11th. Since it was created at 18:50 on the 10th, that's about... 20 hours and 15 minutes. Considering how it only took 13 minutes for #2133 to be vandalized-I-mean-corrected, and 25 minutes for #2125, it seems they're getting slower! I wonder if the poor lil fellas need more attention. :( --[[User:Youforgotthisthing|Youforgotthisthing]] ([[User talk:Youforgotthisthing|talk]]) 00:43, 12 April 2019 (UTC)

Am I the only to one who is amazed at just how *far* Voyager has come? [[Special:Contributions/162.158.111.61|162.158.111.61]] 19:52, 10 April 2019 (UTC)

I thought the dark disk on the photo is 2.6 Schwartzchild radii, not 1? --[[Special:Contributions/172.68.54.46|172.68.54.46]] 20:50, 10 April 2019 (UTC)

I Googled to get a sense of scale. Apparently the sun would be less than 4 miles across if compressed into a black hole. The magnitude is incomprehensible. [[Special:Contributions/172.69.210.64|172.69.210.64]] 02:54, 11 April 2019 (UTC)

I believe "Voyager I" in the title text is a typo and Randall meant to say Voyager II. The location Randall notes would correspond closer to Voyager II than I(9.3 billion miles away from earth vs 11 billion miles). [[Special:Contributions/172.69.247.4|172.69.247.4]] 06:21, 11 April 2019 (UTC)

I updated a few things in the explanation a couple hours back. It should read more smoothly now.
[[User:Fmccarthy|Fmccarthy]] ([[User talk:Fmccarthy|talk]]) 08:01, 12 April 2019 (UTC)
'''Rephrase scale reference'''
2.5 times smaller is not a good way to express reduction in size. It's clearer to say that it's two-fifths as big or it's 40% of the size. [[Special:Contributions/162.158.38.16|162.158.38.16]] 09:58, 11 April 2019 (UTC)
: It's what the official website says. [[User:Numberland|Numberland]] ([[User talk:Numberland|talk]]) 20:28, 14 April 2019 (UTC)

Is anyone agreeing with the source ? haven't found a clear attribution of the image to NSF; and also would be suprised to find one.
: [https://www.nsf.gov/news/mmg/media/images/A-Consensus.jpg NSF link to image], [https://www.nsf.gov/news/news_images.jsp?cntn_id=298276&org=NSF NSF page with attribution], "The National Science Foundation (NSF) played a pivotal role in this discovery by funding individual investigators, interdisciplinary scientific teams and radio astronomy research facilities since the inception of EHT. Over the last two decades, NSF has directly funded more than $28 million in EHT research, the largest commitment of resources for the project." [https://www.nsf.gov/news/news_summ.jsp?cntn_id=298276 Source Article and NSF relation to EHT] --[[Special:Contributions/162.158.106.138|162.158.106.138]] 16:30, 11 April 2019 (UTC)Zenthere
:: but in your news link, the NSF itself gives credit to EHT, so the source should be EHT for the image. Just my opinion.

This is alot like the Pluto comic from a few years back. [[User:Take The A Train To Watertown|Take The A Train To Watertown]] ([[User talk:Take The A Train To Watertown|talk]]) 12:10, 11 April 2019 (UTC)

Why is pluto bigger than the sun? [[User:Lekkin007|Lekkin007]] ([[User talk:Lekkin007|talk]])

:the circle is more likely to be pluto's _orbit_, in which there is a small break, in which there is a small dot, which is more likely to represent pluto. the arrow points to the dot. [[User:Ocæon|ocæon]] ([[User talk:Ocæon|talk]]) 23:03, 12 April 2019 (UTC)

::Lies. If it was pluto's orbit, it would say so. It clearly says Pluto. The small break is probably just a mountain or some other surface anomaly. I think that pluto is actually smaller than the sun, but it was closer to the camera, so it appears bigger. [[Special:Contributions/172.68.51.58|172.68.51.58]] 02:05, 16 April 2019 (UTC)

I am trying to spread truth and good critical thinking, but IP editors keep reverting My well-intention edits! What can I do?
[[Special:Contributions/162.158.107.79|162.158.107.79]] 16:59, 11 April 2019 (UTC)
:See https://www.youtube.com/watch?v=zUyH3XhpLTo[[Special:Contributions/162.158.78.82|162.158.78.82]] 18:26, 11 April 2019 (UTC)
:: HAVE YOU TRIED WALKING INTO THE SEA (can't find the relevant xkcd sorry) on a more serious note, I'd be for banning IP editors myself, it wouldn't matter much and just stop me from editing on mobile. If the comments section could somehow be left IP editable but not the articles, that would be an interesting Midway point, but any degree necessary is fine.{{unsigned|172.68.78.100}}
:::Sign your posts you fucking cunt [[Special:Contributions/162.158.107.97|162.158.107.97]] 15:37, 12 April 2019 (UTC)

:::[[1912: Thermostat]] -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 22:24, 12 April 2019 (UTC)

Anyone else find it ironic for an IP editor to refer to logged-in editors as IP editors? That's the pot calling the brass teapot black! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 06:09, 12 April 2019 (UTC)

As I understand the link "The black hole’s boundary — the event horizon from which the EHT takes its name — is around 2.5 times smaller than the shadow it casts and measures just under 40 billion km across." This is actually showing the wrong scale by a factor of 2.5 - voyager 1 is about at the event horizon, only 40% of the way out of the shadow. Going to edit this but wanted to add discussion here as well. [[User:Numberland|Numberland]] ([[User talk:Numberland|talk]]) 20:28, 14 April 2019 (UTC)

Note that the dimension of the shadow should be measured from the centroid of the ring, not from its inner boundary, since this is a greatly unresolved convolution of a sharp, narrow ring with a roughly gaussian beam from the EHT. Considering that, Munroe's dimensions appear to be essentially correct. -astronomer who happened by this page today but doesn't have an account

2042: Rolle's Theorem

2018-09-07T14:23:30Z

162.158.150.76: Added quotation marks and link

{{comic
| number = 2042
| date = September 5, 2018
| title = Rolle's Theorem
| image = rolles_theorem.png
| titletext = I mean, if it's that easy to get a theorem named for you ... "a straight line that passes through the center of a coplanar circle always divides the circle into two equal halves." Can I have that one? Wait, can I auction off the naming rights? It can be the Red Bull Theorem or the Quicken Loans Theorem, depending who wants it more.
}}

==Explanation==
{{incomplete|Go a little bit more into the explanation.Explain the museum reference. Do NOT delete this tag too soon.}}

In mathematics, a {{w|differentiable function}} is a function that is "smooth" everywhere, without any sudden breaks or pointy "kinks" or similar. The derivative of such a function is a new function that represents the "slope" or "rate of change" of the original. The function in this comic curves up from point (a) until a point above (c), smoothly turns around, and then curves down from (c) to (b). As a result, the derivative of this function is positive from (a) to (c), and then is negative from (c) to (b). At (c) itself, the function is "flat": the more one zooms in, the more horizontal it looks. The function is moving neither up nor down, so the derivative is neither positive nor negative, but zero. This is what ''f'(c) = 0'' means, as ''f''' is a common notation for the derivative of the function ''f'' in {{w|differential calculus}}.

A {{w|theorem}} in mathematics is a statement that has been ''proven'' from former accepted statements, like other theorems or {{w|axiom}}s. This comic references {{w|Rolle's theorem}}. The theorem essentially states that, if a smoothly changing function has the same output at two different inputs, then it must have one or more turning points in between, as the derivative is zero at each one. As a special case, should the function remain flat between the two inputs, then its derivative is actually zero for every point between the inputs. To [[Randall]], this is obvious. However, the proof of this theorem is not as obvious as the result.

The seeming triviality of the theorem, coupled with the honour bestowed on the theorem namer, leads Randall to make a comparison to attendees of art museums who look at abstract art pieces and perceive only an apparent technical simplicity in the work. Such a visitor might exclaim "My child could paint that!". However, such works of art typically are seen as having value from attributes other than the painterly difficulty in achieving the piece. For example, an artist's work in this style may be lauded for its visionary qualities, or the emotions expressed through the choice of colours or textures. One such artist is [http://www.bbc.co.uk/guides/zqhgr82 Jackson Pollock]. The 'clueless' visitor does not see these aspects and believes their child could imitate the piece. Randall suggests he experiences a similar feeling looking at Rolle's Theorem and noting only the obvious correctness without acknowledging the complicated nature of the proof, or other hidden aspects of the theorem.

In the title text, Randall mentions a line together with a ''coplanar'' circle. This simply means that both those two-dimensional objects must lay in the same plane in a higher, three-or-more-dimensional space. And by this means, every line drawn through the center of a circle is just a diameter which divides it into two equal parts. Even if this fact is trivial, {{w|Proclus}} says that the first man who proved it was {{w|Thales of Miletus|Thales}}. Auctioning of {{w|naming rights}}, also noted in the title text, refers to the practice of naming entertainment venues for companies which pay for the privilege, such as any of the three {{w|Red Bull Arena}}s or {{w|Quicken Loans Arena}}. Furthermore, "Rolle's" sounds like "Rolls", a common abbreviation for the {{w|Rolls-Royce_Motor_Cars|Rolls Royce}} brand implying possible sponsorship by the British car manufacturer. The naming of mathematical theorems (along with lemmas, equations, laws, methods, etc.) is [http://www.maa.org/external_archive/devlin/devlin_09_05.html not always straightforward] and {{w|List of misnamed theorems|often results in misleading names}}.

Randall implies that there are many seemingly easy theorems like this. For instance the Dirichlet's box principle, also known as the {{w|Pigeonhole principle}}, that states that if you have more objects than containers, you're going to have to put at least two objects in one container

==Transcript==
:[A single framed picture shows a colored x-y-graph with a text above:]
:'''Rolle's Theorem'''
:From Wikipedia, the free encyclopedia

:Rolle's theorem states that any real, differentiable function that has the same value at two different points must have at least one "stationary point" between them where the slope is zero.

:[The graph shows a sine like curve in blue intersecting the x-axis at points "a" and "b" marked in red while in the middle a point "c" has a vertical dashed green line to the apex and on top also in green f'(c)=0 is drawn with a horizontal line.]

:[Caption below the frame:]
:Every now and then, I feel like the math equivalent of the clueless art museum visitor squinting at a painting and saying "c'mon, my kid could make that."

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Line graphs]]
[[Category:Math]]
[[Category:Wikipedia]]

Talk:2024: Light Hacks

2018-07-26T19:02:22Z

162.158.150.76: IKEA lamp suggested in comments closer to a hypothetical "alien Dyson lampshade".

We all know what we thinking, right :) https://www.youtube.com/watch?v=ECLvFLkvY7Y

Dyson spheres are the future but we’ll never see one in our lifetime, right? Maybe we can build small ones around candles and things as practice. Great art display for your local makerspace! [[Special:Contributions/162.158.63.100|162.158.63.100]] 11:03, 25 July 2018 (UTC)

Here’s a real light hack: https://hackaday.com/2016/02/29/fake-window-brings-natural-light-into-basement/ [[Special:Contributions/162.158.62.183|162.158.62.183]] 15:21, 25 July 2018 (UTC)

I used to think life hacks were cool. Then I read a few of them and realized they were just Hints from Heloise with a cooler, hipper name.[[Special:Contributions/172.68.59.30|172.68.59.30]] 16:17, 25 July 2018 (UTC)Pat

:Pro-tip: Use these five simple tricks to turn any Life Hack into instant click-bait!
:[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 17:57, 25 July 2018 (UTC)

This Ikea lamp is more sci-fi: https://www.ikea.com/us/en/catalog/products/00311498/ [[User:CityZen|CityZen]] ([[User talk:CityZen|talk]]) 20:16, 25 July 2018 (UTC)
:I'm proud to say I actually have that lamp in my bedroom [[User:Faultwire|I'm me(citation needed)]] ([[User talk:Faultwire|talk]]) 23:33, 25 July 2018 (UTC)
::The comic's text specifically mentions that alien "Dyson lampshades" redirect 100% of their energy. By having a shell with mirror coating inside that can be closed and thus indeed reflecting a significant part of the light, they are much closer to what probably was intended[[Special:Contributions/162.158.150.76|162.158.150.76]] 19:02, 26 July 2018 (UTC)

What's the comment about infrared studies being '''inconclusive''' about? I was under the impression that infrared light was one of the big reasons we knew there weren't any Dyson Spheres nearby. Is the comic referring to a study or something I haven't heard of, or am I overthinking this? [[Special:Contributions/162.158.74.243|162.158.74.243]] 02:33, 26 July 2018 (UTC)

:I think she just meant infrared studies to find out if they have them at IKEA. Referencing the fact that that's what you'd use to look for real Dyson spheres. [[User:DanielLC|DanielLC]] ([[User talk:DanielLC|talk]]) 09:23, 26 July 2018 (UTC)

I figured out indirect (diffused) lighting in 1982, in McCutcheon Hall at Purdue University. The central hall had lots of light, but no observable, central light source. I discovered that the light came from hidden fluorescent tubes, diffused against a plastered ceiling. The light we saw, came from overhead, in every direction. The basic outcome is: the more quanta you have, the less precise your measurement can be. OTOH, fewer quanta cast a sharper shadow.

The frosted bulb diffuses the shadows of the filament. The bulb's reflector can be an offset to the diffusion.

1863: Screenshots

2017-07-17T07:37:27Z

162.158.150.76: Fixed missing word

{{comic
| number = 1863
| date = July 14, 2017
| title = Screenshots
| image = screenshots.png
| titletext = For the final exam, you take a screenshot showing off all the work you've done in the class, and it has to survive being uploaded, thumbnailed, and re-screenshotted through a chain of social media sites.
}}

==Explanation==
{{incomplete|Let's add a detailed bullet list explaining every point on the syllabus.}}

The comic shows a syllabus of an introductory course on {{w|Screenshot|screenshots}}. Screenshots have become a common way of spreading and sharing content on social media like Tumblr and Twitter, particularly excerpts of text such as seen in the cartoon. This in turn has developed into a common language with unwritten rules; the comic imagines a world where such rules have become codified into best practices, able to be taught in classes.

The image on the left shows an image of screenshots of text, along with what seems like annotations describing various ratios and dos and don'ts about making such screenshots. The right side shows the main points of the course, touching on topics that are relevant for making and publishing screenshots. Some of these guidelines are violated on a regular basis by people sharing screenshots on the internet, leading to impaired readability and the degradation of digital quality (see [[1683: Digital Data]]).

The punchline of the comic describes a high attendance in the course (presumably many people are interested in how to take high-quality screenshots); however, the digital textbook only sold one copy, implying that the only attendee that bought the book was adept enough to distribute screenshots of the textbook content to the others, because of the information gathered from the class itself. In essence, the writer of the textbook has taught its students how to pirate his material, effectively putting himself out of a job. There isn't anything that the author can do to prevent this due to the {{w|Analog hole|analog hole}}, which states that if non-interactive media can be visually seen by humans, it can be copied, as with a screenshot.

Detailed explanation of the headings on the right:

{| class=wikitable
! Heading
! Explanation

|-
| Highlighting: What & How much?
| This refers to highlighting text of particular interest in screenshots, as depicted on the left.

|-
| Aspect ratios
| Again, depicted on the left. If a screenshot is too wide, it might be difficult to read, and/or it will not fit into thumbnails and social networking feeds. This leads to the screenshot being scaled down too much to be readable (see bottom left). An {{w|aspect ratio}} that is too tall would have similar effects, so in general it is better to stick to near-square aspect ratios (see bottom right of the left section). Some users change the aspect ratio when scaling with a very ugly result (see e.g. [[1187: Aspect Ratio]]).

|-
| Cropping: Pre- and Post-
| This refers to {{w|cropping}} the image, that is, cutting away the irrelevant or unnecessary parts, leaving just the content one needs to communicate.

|-
| Whitespace
| This section presumably deals with {{w|White space (visual arts)|whitespace}} (though "whitespace" is not necessarily white). Whitespace generally refers to the space around the content of interest, which is often but not always white. In the main image on the left side of this comic, most of the red marks are arrows indicating the white space of that image. In this case the "whitespace" at the top and bottom are indeed not white, but rather filled with text not relevant to the screenshot. Removing all whitespace makes an image more efficient and helps provide focus on the important part of a screenshot, but too little whitespace can be less comfortable to read or look at, and therefore appear as a more amateurish result. This section of the course would likely discuss this balance.

|-
| Screenshots vs Links
| For the most part it is recommended that one links to the original content, rather than publishing a screenshot of said content. In some situations it is advisable to opt for using screenshots, such as trying to catch attention on social media, or if the content in question has been removed from the original source, and one still wants to communicate the fact that it was published there.

|-
| Catching the right GIF frame
| A {{w|GIF}} is a bitmap image format that was developed in 1987 by CompuServe and has since come into widespread usage on the World Wide Web due to its wide support and portability. The format supports animations and is often used for short looping animations on the internet. They often employ a low {{w|frame rate}}, so that one might notice a funny or interesting frame during playback. The naïve approach is to press the 'Print Screen' button with careful timing, but in this manner it can be very challenging to capture the desired frame of any GIF that plays at a speed of greater than 5 frames per second. Presumably, the course introduces its students to special tools to get the job done, such as [https://ezgif.com/speed the EZgif website] or the [http://www.xtreme-lab.net/7gif/en/index.html downloadable 7GIF app].
|-
| Snapchat and trust
| {{w|Snapchat}} is a popular social networking application for mobile devices primarily used for sharing images and short videos. One of the main selling points is the transience of content posted. The idea is that as soon as one opens an image or video, a timer starts, and once it has expired the content is no longer accessible on the device. This has led to people sending sensitive content to their friends, thinking that they wouldn't be able to cause much harm, as the content is non-permanent. An obvious flaw in this model is the capability of modern mobile devices to take screenshots (usually available from shortcut keys), and thus permanently save the images to the phone's memory. Saving embarrassing images of one's friends, that they themselves meant as a transient joke, is a serious breach of trust, hence the heading.

|-
| Embarrassing background tabs
| A common error when publishing screenshots is not checking thoroughly enough, and leaving content visible, that might be embarrassing. One such example is {{w|browser tab}}, which might feature content that the creator of the screenshot does not want others to see, such as a page about a sensitive disease one may have (e.g. {{w|AIDS}}) or {{w|pornography}}. Since tabs are small and disconnected from the main content, it is easy to miss such occurrences, which lead to situations such as [http://www.foxnews.com/politics/2017/06/10/lawmaker-mistakenly-hands-out-document-with-porn-references.html this one], where a politician handed out a document with background tabs to pornography websites.

|-
| Spellcheck's red underlines
| {{w|Spell checkers}} are designed to notify the writer of a document of spelling and grammatical mistakes in the text. This is usually done through the editor marking text it thinks is incorrect with an underline (usually red, but other colors may indicate different kinds of mistakes). Sometimes these mistakes are not relevant to the writer, such as when editing {{w|source code}} or using a spellchecker that is set to another language. Even if the corrections are relevant, however, one would not want the ugly red underlines on a screenshot. This section presumably deals with this problem.

|-
| Security: Beware of URL tokens
| {{w|Query string|URL tokens}} are pieces of code embedded in the {{w|URL}} of a website. If implemented well, these help identify a particular document or search query, and do not carry any sensitive security information. Insecure web-apps, however, may encode authentication information (such as {{w|Session_ID|session IDs}}, or even worse: usernames and passwords) in the URL, leading to a massive security risk on the part of someone whose screen might be visible to others. Screenshots allow anyone to easily read off these parameters, and possibly successfully impersonate the creator of the screenshot on a website. This is especially hard to notice to less technically inclined users, who might not know that, say, a session ID (a seemingly random jumble of characters), might be used to impersonate them.

|-
| Redacting personal info
| Somewhat related to the previous point: Screenshots might include personal information, such as indications of institutions one might work for, e-mail addresses, and the like, that one might not want to share with the world. This section presumably deals with ways of obscuring such information on screenshots.

|-
| Useful browser modes
| Using the {{w|Privacy mode|private browsing mode}} offered by most browsers helps with the previous point of keeping your personal information out of the screenshots because websites see you as logged out. Another helpful mode is the full screen browsing mode (usually F11) that will maximize the content to cover the whole screen, keeping the browser UI chrome out of the screenshots. This also helps with privacy, as it will keep the bookmarks on your browser toolbar from being visible, as well as your username if you're logged in Chrome, without having to crop the screenshots manually. Counterpointing with the final bullet on spotting fakes, the Inspect Element browser mode allows you to live-edit the HTML source of the webpage, allowing you to create more convincing fakes if that is your goal.

|-
| Tradeoffs: PNG vs JPG
| {{w|Portable Network Graphics|PNG}} and {{w|JPG}} are file formats with different {{w|image compression|image compression algorithms}}. JPG is widely used for encoding photographs, as it compresses real-world images to a fraction of their normal size without losing much quality. On artificial images with lots of sharp changes in contrast (such as text), however, JPG produces visible {{w|compression artifacts}} due to its {{w|lossy compression}}. For these, PNG is usually used, as it compresses large blocks of a single color, and repeating patterns efficiently, and due to it having a lossless option is able to encode text without artifacts, improving readability. PNG is usually superior for screenshots, as these are artificial images, but if the screenshot is of an actual photo (or a frame of a GIF or movie), JPG might yield lower file sizes at comparable quality. This tradeoff is presumably discussed under the heading.
JPG images also have an attached {{w|EXIF}} data file, not present in PNG images, which may contain information about the device that the screenshot was taken on (especially "with", e.g. a camera) and thus be a potential privacy risk in some cases. However, EXIF metadata is not used with JPEG 2000.

|-
| Watermark ethics
| Many users and websites add {{w|watermarks}} to their original content (or even worse: their screenshots) to indicate where it came from. As depicted in [[1683: Digital Data]] this can lead to degradation of quality as watermarks are stacked on top of each other. It is generally considered okay to put a single unobtrusive watermark on one's own original work; anything other than that would be considered unethical.

|-
| Spotting fakes
| It is relatively easy to fake a screenshot in an image editing program such as {{w|GIMP}} or just editing the page source, making it seem like another organization or person is the original source of the content, possibly damaging their reputation. Some of these techniques are easily detectable by looking at the images {{w|metadata}} or correlating the contents of the screenshot with other sources.

|}

The title text once again refers to the continual re-screenshooting of data as seen in [[1683: Digital Data]], where the final examination consists of the students taking a screenshot good enough that it is still recognizable (and hopefully readable) after being re-compressed, re-screenshot and re-uploaded to various social networking sites, deteriorating its quality. This is quite a difficult task, considering the student only has control over the first screenshot, and subsequent screenshots could degrade the quality to any level. Hopefully the professor is aware of this and plans to perform the test under controlled conditions, as well as grade on a curve.

Screenshots were previously explored by Randall in [[1373: Screenshot]], [[1683: Digital Data]] and [[1815: Flag]]. This comic is one of a small set of comics with the same or almost the same title as another comic (with only the plural form of the word screenshot being the difference).

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:<big>Intro to Screenshots</big>

:[The left side of the panel shows three images. The largest image is a screenshot of text with the middle section highlighted and margins and top and bottom rows marked with red lines and arrows. The two smaller images below are cropped versions of the screenshot in the first image: the left image has an incorrect "squashed" aspect ratio and a red X on it, while the right image has a correct aspect ratio and a green check mark.]

:[The right side of the panel:]

::Syllabus
:*Highlighting: What & how much
:*Aspect ratios
:*Cropping: Pre- and post-
:*Whitespace
:*Screenshots vs links
:*Catching the right GIF frame
:*Snapchat and trust
:*Embarrassing backround tabs
:*Spellcheck's red outlines
:*Security: Beware URL tokens
:*Redacting personal info
:*Useful browser modes
:*Tradeoffs: PNG vs JPG
:*Watermark ethics
:*Spotting fakes

:[Caption below the panel:]
:My class on screenshots was a big hit, although for some reason I only ever sold one copy of the digital textbook.

{{comic discussion}}

[[Category:Comics sharing name|Screenshot02]]
[[Category:Comics with color]]

Talk:1759: British Map

2017-07-03T19:52:02Z

162.158.150.76:

Might be a bit of a stretch, but Cardigan could also be a reference to Ceredigion, the Welsh county. --[[Special:Contributions/172.68.10.34|172.68.10.34]] 16:14, 15 November 2016 (UTC)
:Ceredigion and Cardigan are the same word - Cardigan is just the Anglicised spelling. That's why it was formerly called Cardiganshire. The town is still called Cardigan, which is mentioned in the table. [[User:Schroduck|Schroduck]] ([[User talk:Schroduck|talk]]) 08:34, 16 November 2016 (UTC)
Minas Tirith could be a reference to the gorges in North Somerset. It's slap-bang on Cheddar Gorge and Clifton Village (cliff-town) in Bristol is built on the side of the Avon Gorge. [[User:Camarones|Camarones]] ([[User talk:Camarones|talk]]) 12:54, 15 November 2016 (UTC)

The actual location for Braintree should be Essex not North Yorkshire.
[[Special:Contributions/141.101.98.171|141.101.98.171]] 15:22, 14 November 2016 (UTC)
:When I first saw that, I was wondering how likely a [http://images.neopets.com/halloween/braintree.gif Neopets] reference was. Seeing that it's a real thing, and the creators of Neopets are from the UK, things make a lot more sense now. [[Special:Contributions/108.162.210.196|108.162.210.196]] 14:43, 16 November 2016 (UTC)

Could Highland be a reference to Highlander? [[Special:Contributions/173.245.52.84|173.245.52.84]] 15:27, 14 November 2016 (UTC)

OK, I know you removed the </nowiki> that ruined the italics there, [[User:Davidy22|Davidy]]. Don't lie to me, you troll. [[User:Jacky720|Jacky720]] ([[User talk:Jacky720|talk]]) 19:04, 14 November 2016 (UTC)
:Whoops, was removing autogenerated nowiki text from another user, missed the first tag. Also, that edit was completely unnecessary. 21:29, 14 November 2016 (UTC)
::No it wasn't, see that "Please sign your comments" below? Leaving the <nowiki><nowiki></nowiki> made the italics become quotemarks, and if there hadn't been a </nowiki> at the end of it, it would ruin the rest too. But thanks for apologizing, just try to be more careful. [[User:Jacky720|Jacky720]] ([[User talk:Jacky720|talk]]) 20:08, 15 November 2016 (UTC)

Blick could be referring to Wick , at the top of Scotland ''Please sign your comments with <nowiki>~~~~</nowiki>''

''Waterdown: Near [the actual] Grimsby'' Interestingly enough, in southern Ontario, Canada, there's a Waterdown not far from a Grimsby. Waterdown is considered part of Hamilton, and is towards its northwestern edge, while Grimsby is to Hamilton's east. --[[User:VonAether|VonAether]] ([[User talk:VonAether|talk]]) 17:01, 14 November 2016 (UTC)

The protractor off the West coast of Scotland is a reference to https://en.wikipedia.org/wiki/Mull_of_Kintyre_test
[[Special:Contributions/141.101.98.215|141.101.98.215]] 17:44, 14 November 2016 (UTC)

Blick could also be Oldmeldrum.
[[Special:Contributions/162.158.234.229|162.158.234.229]] 19:06, 14 November 2016 (UTC)

Why aren't the coordinates part of the first table? [[User:NotLock|NotLock]] ([[User talk:NotLock|talk]]) 20:05, 14 November 2016 (UTC)

Is Waterdown perhaps another Watership Down reference? [[User:Miamiclay|Miamiclay]] ([[User talk:Miamiclay|talk]]) 20:38, 14 November 2016 (UTC)

Pity there's no [[wikipedia:Towcester|Towcester]] :) [[Special:Contributions/141.101.98.251|141.101.98.251]] 20:47, 14 November 2016 (UTC)

"Lakebottom" is equated with Lake Windermere (probably correct, largest lake in the Lake District) and the table states that many waterspeed records were set there. Arguably it is Coniston Water (same area, third largest "Lake" in the region) that is more (in) famous for speed records... Not that Randall references speed at all. [[Special:Contributions/141.101.98.159|141.101.98.159]] 21:31, 14 November 2016 (UTC)

I agree with this, Windermere was home to only one (successful) water speed record attempt. Coniston is more popular for them as it doesn't have as many islands, so you can get a longer run in. Also, whichever one it is, it is drawn roughly east-west, whereas both Coniston and Windermere run north-south.

For me, the lake with the two boats is an obvious reference to the children's book 'Swallows and Amazons'. [https://en.wikipedia.org/wiki/Swallows_and_Amazons#Places_in_Swallows_and_Amazons See wikipedia] -- so these are neither speedboats nor yachts but rather sailing dinghies. There is however a discrepancy: they had a gaff rig, but it looks like Randall gave them a Bermuda rig.

Helcaraxë and Blick seem to share a single dot. Maybe Randall forgot to put a dot there, or there's some other reason? --[[Special:Contributions/108.162.216.112|108.162.216.112]] 22:58, 14 November 2016 (UTC)
:Helcaraxë and Highlands are areas, not towns, so don't get dots. [[Special:Contributions/198.41.239.32|198.41.239.32]] 07:18, 16 November 2016 (UTC)

since Randal Munroe wrote the comic, and he is an american, the map WAS labeled by an american[[User:Jessep13|Jessep13]] ([[User talk:Jessep13|talk]]) 00:08, 15 November 2016 (UTC)

‘Seasedge’ and ‘Eyemouth’ look like they should be Seahouses and Lynemouth. So far as I can tell, Seasedge is marked as a little north of Seahouses, roughly west of Lindisfarne (which suggests Haggerston; regardless, north Northumberland coast), and Eyemouth is marked approximately where Ashington should be; ‘Hairskull’ appears to be where Durham should be. [[Special:Contributions/141.101.98.160|141.101.98.160]] 02:33, 15 November 2016 (UTC)

"BBC Channel 4" might also be a reference to Torchwood and other BBC Shows that were filmed in Wales (though did not necessarily air on Channel 4) [[User:Bpendragon|Bpendragon]] ([[User talk:Bpendragon|talk]]) 03:04, 15 November 2016 (UTC)

In fact, "Channel 4" is a channel not related to the BBC, so the reference to "BBC Channel 4" would be a mash-up between "Channel 4" and "BBC4" [[User:Gearoid|Gearóid]] ([[User talk:Gearoid|talk]]) 07:30, 15 November 2016 (UTC)

"Wessex", although "obsolete" as a place name, is still in common use as a descriptive term. For example, there is both a Wessex Police Force and a Wessex Water supply company. [[User:Gearoid|Gearóid]] ([[User talk:Gearoid|talk]]) 08:30, 15 November 2016 (UTC)

I know the "Fhqwhgads" reference from the Ikea-ripoff video game Home Improvisation - always thought it was a pun in that game on Ikea's Swedish product names. Is the Homestar Runner reference older? [[Special:Contributions/141.101.98.162|141.101.98.162]] 09:05, 15 November 2016 (UTC)
:I always thought it originated in Homestar Runner as a randomly typed name of an email sender. It's from Strong Bad Email #9 dated January 14, 2002, far predating Home Improvisation from 2015. [[Special:Contributions/108.162.221.243|108.162.221.243]] 14:35, 15 November 2016 (UTC)

"Aidenn" is an alternate form of "Eden." It's best known for Poe's using it in "The Raven." If the actual location is Merseyside, it could be a wordplay suggesting divine mercy. [[User:Gmcgath|Gmcgath]] ([[User talk:Gmcgath|talk]]) 11:25, 15 November 2016 (UTC)

The “hey then” explanation for “Aidenn” is so tortured as to be implausible. It should be changed per the above comment. [[Special:Contributions/172.68.55.81|172.68.55.81]] 13:19, 15 November 2016 (UTC)

The text [[http://cogink.com/cleese/]] that is referenced for "The Shire" and attributed to John Cleese is actually a hoax, see http://www.snopes.com/politics/soapbox/revocation.asp [[Special:Contributions/141.101.98.181|141.101.98.181]] 10:19, 16 November 2016 (UTC)
:And the reference in this piece to the incorrectness of "Devonshire" is completely wrong. Although the official name of the county is now "Devon", the form "Devonshire" has a pedigree going back over 1000 years and is still used in formations such as the Duke of Devonshire, HMS Devonshire, the Devonshire Regiment etc. The same goes for Dorset/Dorsetshire. [[User:Mikej|Mikej]] ([[User talk:Mikej|talk]]) 13:09, 16 November 2016 (UTC)

"Tarp" probably refers to the meme "It's a tarp!": http://www.urbandictionary.com/define.php?term=It%27s%20a%20tarp. [[User:Yodah|Yodah]] ([[User talk:Yodah|talk]]) 11:57, 16 November 2016 (UTC)

;Riffing on Boston?

The title text may be derivitive of an old joke around Randall's home town, where Boston has neighborhoods with geographically illogical names: The geographical center of Boston is in Roxbury. Due north of the center we find the South End.
This is not to be confused with South Boston, which lies directly east from the South End.
North of the South End is East Boston and southwest of East Boston is the North End. BackBay was filled in years ago

Also, from the counties surrounding Boston: Norfolk is mostly south of Suffolk, except for a small gerrymandered piece that is in the middle between Suffolk and Middlesex.

;Bottoms
"Bottoms" are not confined to Northern England. We have many bottoms here in Kent, which is not Northern. (See Lock's Bottom and Pratt's Bottom.) Also, "bottom" may refer to somewhere that is lower than somewhere else, but not necessarily in a valley as such. Also also, snurk. --[[Special:Contributions/141.101.98.143|141.101.98.143]] 12:45, 15 November 2016 (UTC)

: "Bottoms" is not confined to Europe either, so don't feel special - we land-dwellers in North America use it too, usually to mean 'Low-lying alluvial land adjacent to a river' as defined in the dictionary! In more general terms, this would refer to land subject to frequent flooding, commonly called a floodplain. If you have a bottoms that never floods, you really should consider renaming it. --[[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 04:15, 6 June 2017 (UTC)

*And "-folk" is not common in place names. It exists in Suffolk and Norfolk but two (among thousands) can't be called common. --[[Special:Contributions/141.101.98.143|141.101.98.143]] 12:53, 15 November 2016 (UTC)

Crewneck could also refer to actual crewneck sweaters, popularised by The Beatles in the 60's. The Beatles came from Liverpool... {{unsigned ip|108.162.246.41}}

Blighton would be pronounced the same as the surname of Enid Blyton (1897-1968), a famous author of childrens' books known for their resolute white middle class-ness. But she is associated with southern England; she lived in Beaconsfield, west of London. [[Special:Contributions/172.68.55.82|172.68.55.82]] 16:22, 24 November 2016 (UTC)

While I found this comic funny, what I found most humorous was the reactions to it. Facts: Randall drew a map of Britain, he said it was labeled by an American, and it included both real and made-up place names. Unfortunately, it seems that those commenting here and generating this article interpreted it as an American-bashing opportunity. I interpreted it as this: to the average American, Britain has a LOT of funny names for places and struggles with using appropriate directional prefixes. It's extremely funny how so many of you chose to see it in the least funny way possible, likely because you can only see it through your own eyes! --[[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 05:14, 6 June 2017 (UTC)

Talk:1759: British Map

2017-07-03T19:44:10Z

162.158.150.76:

Might be a bit of a stretch, but Cardigan could also be a reference to Ceredigion, the Welsh county. --[[Special:Contributions/172.68.10.34|172.68.10.34]] 16:14, 15 November 2016 (UTC)
:Ceredigion and Cardigan are the same word - Cardigan is just the Anglicised spelling. That's why it was formerly called Cardiganshire. The town is still called Cardigan, which is mentioned in the table. [[User:Schroduck|Schroduck]] ([[User talk:Schroduck|talk]]) 08:34, 16 November 2016 (UTC)
Minas Tirith could be a reference to the gorges in North Somerset. It's slap-bang on Cheddar Gorge and Clifton Village (cliff-town) in Bristol is built on the side of the Avon Gorge. [[User:Camarones|Camarones]] ([[User talk:Camarones|talk]]) 12:54, 15 November 2016 (UTC)

The actual location for Braintree should be Essex not North Yorkshire.
[[Special:Contributions/141.101.98.171|141.101.98.171]] 15:22, 14 November 2016 (UTC)
:When I first saw that, I was wondering how likely a [http://images.neopets.com/halloween/braintree.gif Neopets] reference was. Seeing that it's a real thing, and the creators of Neopets are from the UK, things make a lot more sense now. [[Special:Contributions/108.162.210.196|108.162.210.196]] 14:43, 16 November 2016 (UTC)

Could Highland be a reference to Highlander? [[Special:Contributions/173.245.52.84|173.245.52.84]] 15:27, 14 November 2016 (UTC)

OK, I know you removed the </nowiki> that ruined the italics there, [[User:Davidy22|Davidy]]. Don't lie to me, you troll. [[User:Jacky720|Jacky720]] ([[User talk:Jacky720|talk]]) 19:04, 14 November 2016 (UTC)
:Whoops, was removing autogenerated nowiki text from another user, missed the first tag. Also, that edit was completely unnecessary. 21:29, 14 November 2016 (UTC)
::No it wasn't, see that "Please sign your comments" below? Leaving the <nowiki><nowiki></nowiki> made the italics become quotemarks, and if there hadn't been a </nowiki> at the end of it, it would ruin the rest too. But thanks for apologizing, just try to be more careful. [[User:Jacky720|Jacky720]] ([[User talk:Jacky720|talk]]) 20:08, 15 November 2016 (UTC)

Blick could be referring to Wick , at the top of Scotland ''Please sign your comments with <nowiki>~~~~</nowiki>''

''Waterdown: Near [the actual] Grimsby'' Interestingly enough, in southern Ontario, Canada, there's a Waterdown not far from a Grimsby. Waterdown is considered part of Hamilton, and is towards its northwestern edge, while Grimsby is to Hamilton's east. --[[User:VonAether|VonAether]] ([[User talk:VonAether|talk]]) 17:01, 14 November 2016 (UTC)

The protractor off the West coast of Scotland is a reference to https://en.wikipedia.org/wiki/Mull_of_Kintyre_test
[[Special:Contributions/141.101.98.215|141.101.98.215]] 17:44, 14 November 2016 (UTC)

Blick could also be Oldmeldrum.
[[Special:Contributions/162.158.234.229|162.158.234.229]] 19:06, 14 November 2016 (UTC)

Why aren't the coordinates part of the first table? [[User:NotLock|NotLock]] ([[User talk:NotLock|talk]]) 20:05, 14 November 2016 (UTC)

Is Waterdown perhaps another Watership Down reference? [[User:Miamiclay|Miamiclay]] ([[User talk:Miamiclay|talk]]) 20:38, 14 November 2016 (UTC)

Pity there's no [[wikipedia:Towcester|Towcester]] :) [[Special:Contributions/141.101.98.251|141.101.98.251]] 20:47, 14 November 2016 (UTC)

"Lakebottom" is equated with Lake Windermere (probably correct, largest lake in the Lake District) and the table states that many waterspeed records were set there. Arguably it is Coniston Water (same area, third largest "Lake" in the region) that is more (in) famous for speed records... Not that Randall references speed at all. [[Special:Contributions/141.101.98.159|141.101.98.159]] 21:31, 14 November 2016 (UTC)

I agree with this, Windermere was home to only one (successful) water speed record attempt. Coniston is more popular for them as it doesn't have as many islands, so you can get a longer run in. Also, whichever one it is, it is drawn roughly east-west, whereas both Coniston and Windermere run north-south.

Helcaraxë and Blick seem to share a single dot. Maybe Randall forgot to put a dot there, or there's some other reason? --[[Special:Contributions/108.162.216.112|108.162.216.112]] 22:58, 14 November 2016 (UTC)
:Helcaraxë and Highlands are areas, not towns, so don't get dots. [[Special:Contributions/198.41.239.32|198.41.239.32]] 07:18, 16 November 2016 (UTC)

since Randal Munroe wrote the comic, and he is an american, the map WAS labeled by an american[[User:Jessep13|Jessep13]] ([[User talk:Jessep13|talk]]) 00:08, 15 November 2016 (UTC)

‘Seasedge’ and ‘Eyemouth’ look like they should be Seahouses and Lynemouth. So far as I can tell, Seasedge is marked as a little north of Seahouses, roughly west of Lindisfarne (which suggests Haggerston; regardless, north Northumberland coast), and Eyemouth is marked approximately where Ashington should be; ‘Hairskull’ appears to be where Durham should be. [[Special:Contributions/141.101.98.160|141.101.98.160]] 02:33, 15 November 2016 (UTC)

"BBC Channel 4" might also be a reference to Torchwood and other BBC Shows that were filmed in Wales (though did not necessarily air on Channel 4) [[User:Bpendragon|Bpendragon]] ([[User talk:Bpendragon|talk]]) 03:04, 15 November 2016 (UTC)

In fact, "Channel 4" is a channel not related to the BBC, so the reference to "BBC Channel 4" would be a mash-up between "Channel 4" and "BBC4" [[User:Gearoid|Gearóid]] ([[User talk:Gearoid|talk]]) 07:30, 15 November 2016 (UTC)

"Wessex", although "obsolete" as a place name, is still in common use as a descriptive term. For example, there is both a Wessex Police Force and a Wessex Water supply company. [[User:Gearoid|Gearóid]] ([[User talk:Gearoid|talk]]) 08:30, 15 November 2016 (UTC)

I know the "Fhqwhgads" reference from the Ikea-ripoff video game Home Improvisation - always thought it was a pun in that game on Ikea's Swedish product names. Is the Homestar Runner reference older? [[Special:Contributions/141.101.98.162|141.101.98.162]] 09:05, 15 November 2016 (UTC)
:I always thought it originated in Homestar Runner as a randomly typed name of an email sender. It's from Strong Bad Email #9 dated January 14, 2002, far predating Home Improvisation from 2015. [[Special:Contributions/108.162.221.243|108.162.221.243]] 14:35, 15 November 2016 (UTC)

"Aidenn" is an alternate form of "Eden." It's best known for Poe's using it in "The Raven." If the actual location is Merseyside, it could be a wordplay suggesting divine mercy. [[User:Gmcgath|Gmcgath]] ([[User talk:Gmcgath|talk]]) 11:25, 15 November 2016 (UTC)

The “hey then” explanation for “Aidenn” is so tortured as to be implausible. It should be changed per the above comment. [[Special:Contributions/172.68.55.81|172.68.55.81]] 13:19, 15 November 2016 (UTC)

The text [[http://cogink.com/cleese/]] that is referenced for "The Shire" and attributed to John Cleese is actually a hoax, see http://www.snopes.com/politics/soapbox/revocation.asp [[Special:Contributions/141.101.98.181|141.101.98.181]] 10:19, 16 November 2016 (UTC)
:And the reference in this piece to the incorrectness of "Devonshire" is completely wrong. Although the official name of the county is now "Devon", the form "Devonshire" has a pedigree going back over 1000 years and is still used in formations such as the Duke of Devonshire, HMS Devonshire, the Devonshire Regiment etc. The same goes for Dorset/Dorsetshire. [[User:Mikej|Mikej]] ([[User talk:Mikej|talk]]) 13:09, 16 November 2016 (UTC)

"Tarp" probably refers to the meme "It's a tarp!": http://www.urbandictionary.com/define.php?term=It%27s%20a%20tarp. [[User:Yodah|Yodah]] ([[User talk:Yodah|talk]]) 11:57, 16 November 2016 (UTC)

;Riffing on Boston?

The title text may be derivitive of an old joke around Randall's home town, where Boston has neighborhoods with geographically illogical names: The geographical center of Boston is in Roxbury. Due north of the center we find the South End.
This is not to be confused with South Boston, which lies directly east from the South End.
North of the South End is East Boston and southwest of East Boston is the North End. BackBay was filled in years ago

Also, from the counties surrounding Boston: Norfolk is mostly south of Suffolk, except for a small gerrymandered piece that is in the middle between Suffolk and Middlesex.

;Bottoms
"Bottoms" are not confined to Northern England. We have many bottoms here in Kent, which is not Northern. (See Lock's Bottom and Pratt's Bottom.) Also, "bottom" may refer to somewhere that is lower than somewhere else, but not necessarily in a valley as such. Also also, snurk. --[[Special:Contributions/141.101.98.143|141.101.98.143]] 12:45, 15 November 2016 (UTC)

: "Bottoms" is not confined to Europe either, so don't feel special - we land-dwellers in North America use it too, usually to mean 'Low-lying alluvial land adjacent to a river' as defined in the dictionary! In more general terms, this would refer to land subject to frequent flooding, commonly called a floodplain. If you have a bottoms that never floods, you really should consider renaming it. --[[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 04:15, 6 June 2017 (UTC)

*And "-folk" is not common in place names. It exists in Suffolk and Norfolk but two (among thousands) can't be called common. --[[Special:Contributions/141.101.98.143|141.101.98.143]] 12:53, 15 November 2016 (UTC)

Crewneck could also refer to actual crewneck sweaters, popularised by The Beatles in the 60's. The Beatles came from Liverpool... {{unsigned ip|108.162.246.41}}

Blighton would be pronounced the same as the surname of Enid Blyton (1897-1968), a famous author of childrens' books known for their resolute white middle class-ness. But she is associated with southern England; she lived in Beaconsfield, west of London. [[Special:Contributions/172.68.55.82|172.68.55.82]] 16:22, 24 November 2016 (UTC)

While I found this comic funny, what I found most humorous was the reactions to it. Facts: Randall drew a map of Britain, he said it was labeled by an American, and it included both real and made-up place names. Unfortunately, it seems that those commenting here and generating this article interpreted it as an American-bashing opportunity. I interpreted it as this: to the average American, Britain has a LOT of funny names for places and struggles with using appropriate directional prefixes. It's extremely funny how so many of you chose to see it in the least funny way possible, likely because you can only see it through your own eyes! --[[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 05:14, 6 June 2017 (UTC)

For me, the lake with the two boats is an obvious reference to the children's book 'Swallows and Amazons'. [https://en.wikipedia.org/wiki/Swallows_and_Amazons#Places_in_Swallows_and_Amazons See wikipedia] -- so these are neither speedboats nor yachts but rather sailing dinghies. There is however a discrepancy: they had a gaff rig, but it looks like Randall gave them a Bermuda rig.

Talk:1826: Birdwatching

2017-04-19T09:16:57Z

162.158.150.76: Forgotten "signature"

This is a big one.[[Special:Contributions/108.162.246.41|108.162.246.41]] 04:07, 19 April 2017 (UTC)

I wonder if the size is a technical error, or if I am missing some subtle joke. [[Special:Contributions/108.162.245.184|108.162.245.184]] 04:37, 19 April 2017 (UTC)

I guess it's the latter. [[Special:Contributions/162.158.166.71|162.158.166.71]] 04:39, 19 April 2017 (UTC)

I think the vacuum is a further joke about scale and distance playing on the absurdity of trying to vacuum from a range of one mile. I must say I don't really understand this comic very well.[[Special:Contributions/108.162.245.70|108.162.245.70]] 04:47, 19 April 2017 (UTC)

I thought the vacuum was trying to drain the atmosphere to make it so that the birds can't fly as high.[[User:1I1III1|1I1III1]] ([[User talk:1I1III1|talk]]) 05:42, 19 April 2017 (UTC)
: That was my thought, too. (/edit: Honestly, to think of sucking the birds in I found being too absurd, while sucking the atmosphere seemed absolutely plausible - at least for an XKCD...) [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 08:18, 19 April 2017 (UTC)

Are these the same birds from 1824? [[User:Codrus|Codrus]] ([[User talk:Codrus|talk]]) 06:16, 19 April 2017 (UTC)

Pretty sure the size is an error, I've seen this happen briefly before. It's 1200 dpi, suitable for archival, printing, or just what comes off the scanner [[Special:Contributions/108.162.246.107|108.162.246.107]] 09:04, 19 April 2017 (UTC)

Hey folks, am I the only one thinking that Cueball also holds the binoculars the wrong way around? Usually the small end is nearest to the eyes... That would for sure make birdwatching even MORE difficult. Regarding size, I think it is intentional.[[Special:Contributions/162.158.150.76|162.158.150.76]] 09:16, 19 April 2017 (UTC)

Talk:1826: Birdwatching

2017-04-19T09:16:08Z

162.158.150.76:

1814: Color Pattern

2017-03-24T06:50:49Z

162.158.150.76: /* The songs */ typo

{{comic
| number = 1814
| date = March 22, 2017
| title = Color Pattern
| image = color_pattern.png
| titletext = ♫ When the spacing is tight / And the difference is slight / That's a moiré ♫
}}

==Explanation==
{{incomplete| Is the title text explanation correct?}}
The comic references {{w|moiré pattern}}s in a parody of the song “{{w|That's Amore}}” made famous by {{w|Dean Martin}} [https://www.youtube.com/watch?v=RnoDb0bMQuk in 1953]. (See [[#Trivia|trivia]] for pronunciation).

[[Cueball]] complains that the photo he just took of his computer screen is covered in weird rainbow patterns (the color patterns from the title). In photography (or videography), a moiré pattern occurs when the image sensors are aligned in a pattern, while photographing something else that is also aligned in a pattern that's not 100% identically aligned.

In mathematics, physics, and art, a moiré pattern or moiré fringes are large scale interference patterns that can be produced when an opaque ruled pattern with transparent gaps is overlaid on another similar pattern. For the moiré interference pattern to appear, the two patterns must not be completely identical in that they must be displaced, rotated, etc., or have different but similar pitch. A moiré pattern is a kind of {{w|aliasing}}. Moiré patterns appear in many different situations. In printing, the printed pattern of dots can negatively interfere with the image. In television and digital photography, a pattern on an object being photographed can interfere with the shape of the light sensors to generate unwanted {{w|artifact (error)|artifacts}}.

Photographs of a digital screen taken with a digital camera often exhibit moiré patterns. Since both the screen and the digital camera use a scanning technique to produce or to capture pictures with horizontal scan lines, the conflicting sets of lines cause the moiré patterns. To avoid the effect, the digital camera can be aimed at an angle of 30 degrees to the screen.

[[Megan]] replies with a song that explains that what Cueball sees is a moiré pattern. But she chooses to use the song ''That's Amore'', where "Amore" means "love" in Italian. The pun is that "That's a Moiré" and "That's Amore" are phonetically [[#Trivia|quite similar]]. Her explanation that it happens when a grid is misaligned with another behind fits well with the more detailed explanation above.

[[#The songs|The song]] has a second verse given in the title text, again with musical notes indicating that it should be song. More information on when moiré patterns occur is given here, indicating that the space between the grid lines should be small and the two grids should be almost identical, for the maximum moiré effect.

===The songs===
The entire version of Megan's ([[Randall|Randall's]]) song is:
:When a grid's misaligned
:with another behind
:That's a moiré...

:When the spacing is tight
:And the difference is slight
:That's a moiré

The two first verse in the [http://www.metrolyrics.com/thats-amore-lyrics-dean-martin.html original song]:
:When a moon hits your eye
:like a big pizza pie
:That's amore

:When the world seems to shine
:like you've had too much wine
:That's amore

A similar song based on the same pun was made by Craig Swanson in 1993 and can be found on his web comic [http://www.perspicuity.com/ Perspicuity] in this comic: [http://www.perspicuity.com/?lightbox=image_104h That's a Moiré]. His song text was:
:When new lines hit your eyes
:From two screens when they ply
:That's a Moire!

==Transcript==
:[Cueball holds up his smartphone in front of his laptop which stands in front of him on a desk. Megan is sitting in an armchair reading, facing away from Cueball. She is singing her reply, as indicated with four double musical notes around her two lines of text.]
:Cueball: I took a picture of my computer screen—why is the photo covered in these weird rainbow patterns?
:Megan: ''When a grid's misaligned with another behind''
:Megan: ''That's a moiré...''

==Trivia==
*Pronunciation:
**Moiré ([http://www.oxfordlearnersdictionaries.com/definition/english/moire /ˈmwɑːreɪ/] – /mwɑˈreɪ/ – [http://www.dictionary.com/browse/moire- French:] [mwaˈʁe])
**That’s amore /ðæts aˈmɔːrɛ/.
**That’s a moiré /ðæts ə ˈmwɑːreɪ/.
*Comic [[321: Thighs]] also made a joke out of changing the lyrics of this song, “That’s Amore”.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Smartphones]]
[[Category:Songs]]

Talk:1793: Soda Sugar Comparisons

2017-02-01T16:07:14Z

162.158.150.76:

And that's why I don't really drink soda. [[User:Cardboardmech|Cardboardmech]] ([[User talk:Cardboardmech|talk]]) 06:30, 1 February 2017 (UTC)
:...sadly, coke zero costs as much as normal coke, despite one having 0% sugar, and thus, give the body zero energy. No financial incentive to switch. :D --[[Special:Contributions/162.158.150.76|162.158.150.76]] 10:52, 1 February 2017 (UTC)
:The problem is that juice (like orange-juice) has not that much less sugar – and if you drink not pure juice, it can has more. --[[User:DaB.|DaB.]] ([[User talk:DaB.|talk]]) 15:16, 1 February 2017 (UTC)

Stellar work from [[User:Schroduck|Schroduck]] but can we get a better idea of the calories in a candy counter. We're looking at approx 3000 candy bars (a catering box holds 48 bars, is designed to be usable for display and about 2 bars wide) ballpark figures though so not adding the edit yet, but 3 tiers of boxes would be about right [[User:Luckykaa|Luckykaa]] ([[User talk:Luckykaa|talk]]) 09:26, 1 February 2017 (UTC)
:Thanks! I did a bit of digging, and updated the data. It looks like it significantly overestimates the sugar (''if'' the display only holds chocolate/candy and not, say, sugar-free gum). [[User:Schroduck|Schroduck]] ([[User talk:Schroduck|talk]]) 11:56, 1 February 2017 (UTC)

One issue I have personally with these comparison are that it is easy to get huge numbers just by adding time. However, in this case, if you translate this into body fat it does make sense. Another tangent: Eating an orange is 9 grams of sugar according to google sources. 7 oranges per day is a lot of fruit. Throwing this out there for anyone to play with. [[Special:Contributions/141.101.80.214|141.101.80.214]] 11:07, 1 February 2017 (UTC)

The page mentions "Crème eggs." While this is a common autocorrect, Cadbury don't use this on their packaging. Confusingly, this appears to be the case in the USA as well, even though Hershey on its website uses it. Can someone find a citation to confirm or deny that this this is ever the correct spelling? Also, don't drink soda. Really. --[[Special:Contributions/141.101.107.18|141.101.107.18]] 13:21, 1 February 2017 (UTC)

I don't like how he compares the consumption of soda at a constant rate over a period of time to a grand total of candy. This could be reversed, e.g. eating 100ml of skittles a day for six months is the same as drinking 180 bottles of soda, to make it seem as though candy contains a lot of sugar in comparison to soda rather than vice versa. [[Special:Contributions/141.101.99.239|141.101.99.239]] 14:10, 1 February 2017 (UTC)
:Yes, it's a real problem that these comparisons don't dig at the core of the problem - that carbohydrate-rich food is often junk food. You can store lots of fat for a long time, but not carbohydrates (the human stores are maxed out at +/- 1200 g for an adult male). So, apart from athletes, nobody manages to deplete these stores in the liver and the muscles. Nobody, apart from athletes, has therefore a genuine need for carbohydrate-rich food. Our consumption of carbohydrates is like refilling a car's gasoline tank even if it is 90% full.[[Special:Contributions/162.158.150.76|162.158.150.76]] 14:36, 1 February 2017 (UTC)
::You forgot that the human body can convert sugar to fat quite easily. --[[User:DaB.|DaB.]] ([[User talk:DaB.|talk]]) 15:16, 1 February 2017 (UTC)
:::...which is not a reason for sugar consumption. --[[Special:Contributions/162.158.150.76|162.158.150.76]] 16:07, 1 February 2017 (UTC)

Talk:1793: Soda Sugar Comparisons

2017-02-01T14:36:14Z

162.158.150.76:

And that's why I don't really drink soda. [[User:Cardboardmech|Cardboardmech]] ([[User talk:Cardboardmech|talk]]) 06:30, 1 February 2017 (UTC)
:...sadly, coke zero costs as much as normal coke, despite one having 0% sugar, and thus, give the body zero energy. No financial incentive to switch. :D --[[Special:Contributions/162.158.150.76|162.158.150.76]] 10:52, 1 February 2017 (UTC)

Stellar work from [[User:Schroduck|Schroduck]] but can we get a better idea of the calories in a candy counter. We're looking at approx 3000 candy bars (a catering box holds 48 bars, is designed to be usable for display and about 2 bars wide) ballpark figures though so not adding the edit yet, but 3 tiers of boxes would be about right [[User:Luckykaa|Luckykaa]] ([[User talk:Luckykaa|talk]]) 09:26, 1 February 2017 (UTC)
:Thanks! I did a bit of digging, and updated the data. It looks like it significantly overestimates the sugar (''if'' the display only holds chocolate/candy and not, say, sugar-free gum). [[User:Schroduck|Schroduck]] ([[User talk:Schroduck|talk]]) 11:56, 1 February 2017 (UTC)

One issue I have personally with these comparison are that it is easy to get huge numbers just by adding time. However, in this case, if you translate this into body fat it does make sense. Another tangent: Eating an orange is 9 grams of sugar according to google sources. 7 oranges per day is a lot of fruit. Throwing this out there for anyone to play with. [[Special:Contributions/141.101.80.214|141.101.80.214]] 11:07, 1 February 2017 (UTC)

The page mentions "Crème eggs." While this is a common autocorrect, Cadbury don't use this on their packaging. Confusingly, this appears to be the case in the USA as well, even though Hershey on its website uses it. Can someone find a citation to confirm or deny that this this is ever the correct spelling? Also, don't drink soda. Really. --[[Special:Contributions/141.101.107.18|141.101.107.18]] 13:21, 1 February 2017 (UTC)

I don't like how he compares the consumption of soda at a constant rate over a period of time to a grand total of candy. This could be reversed, e.g. eating 100ml of skittles a day for six months is the same as drinking 180 bottles of soda, to make it seem as though candy contains a lot of sugar in comparison to soda rather than vice versa. [[Special:Contributions/141.101.99.239|141.101.99.239]] 14:10, 1 February 2017 (UTC)
:Yes, it's a real problem that these comparisons don't dig at the core of the problem - that carbohydrate-rich food is often junk food. You can store lots of fat for a long time, but not carbohydrates (the human stores are maxed out at +/- 1200 g for an adult male). So, apart from athletes, nobody manages to deplete these stores in the liver and the muscles. Nobody, apart from athletes, has therefore a genuine need for carbohydrate-rich food. Our consumption of carbohydrates is like refilling a car's gasoline tank even if it is 90% full.[[Special:Contributions/162.158.150.76|162.158.150.76]] 14:36, 1 February 2017 (UTC)

Talk:1793: Soda Sugar Comparisons

2017-02-01T10:52:36Z

162.158.150.76:

1791: Telescopes: Refractor vs Reflector

2017-01-30T02:52:13Z

162.158.150.76: /* Explanation */

{{comic
| number = 1791
| date = January 27, 2017
| title = Telescopes: Refractor vs Reflector
| image = telescopes_refractor_vs_reflector.png
| titletext = On the other hand, the refractor's limited light-gathering means it's unable to make out shadow people or the dark god Chernabog.
}}

==Explanation==
This comic compares two major types of {{w|optical telescope}}: The {{w|refracting telescope}} and the {{w|reflecting telescope}}. A refracting telescope produces an image with a series of lenses. A reflecting telescope uses mirrors. (A third type, the {{w|catadioptric system}} telescope, uses both mirrors ''and'' lenses. It is not shown here.)

It first looks like the comic is simply trying to show that refracting has many flaws, such as expense, size and visibility (see more [[#The real problems with refracting telescopes|details below]]). However, the punchline invalidates these complaints with the (apparently major) flaw listed with the reflecting telescope: '''It can't see space vampires'''.

The unstated reason for this is that {{w|vampires}}, {{w|Vampire#Apotropaics|according to some cultures}}, cannot be seen in a mirror. As {{w|space vampires}} (like earth vampires) are widely believed to be {{w|Vampire#Origins_of_vampire_beliefs|made up}} and thus unlikely to interest most [[1644: Stargazing|stargazers]], this complaint is superfluous, and the reflecting telescope effectively has no flaws in comparison to the refracting telescope. There are other problems, though, with reflecting telescopes see [[#The real problems with reflecting telescope|details below]]. (Also there was a big problem in the [[#Trivia|original version of this comic]]).

Frequently, however, the right-angle transition at the base of the refractor telescope is done with a prism (an "image erector"). This uses the optical principle of total internal reflection. If mirror-non-appearance of vampires is due to the interaction of evil with silver, a refractor using a prism could still see vampires. On this theory, however, the reflector could too, since modern astronomical mirrors are coated with aluminum, not silver.

The title text expands on the seeing of supernatural beings, as another negative point is added to the refracting telescope; it apparently can't see {{w|Shadow person|Shadow People}} or the Slavic god {{w|Chernobog|Chernabog}} (normally spelled Chernobog), both of which are important although clearly not as important to the telescope's merit as seeing vampires since the fact is only mentioned in the title text. So of course the refracting telescope is still the best. Of course also neither the {{w|Shadow_person#History_and_folklore|shadow people}} nor {{w|Chernobog#Folklore|the god}} exists so this would likewise be a moot point.

In reality, "shadow people" are a psychological phenomenon wherein humans ascribe human shapes and movements to shadows in dark spaces. Chernobog is a 12th century Slavic deity, whose name translates to ''black god''. His most famous appearance in modern media was in the 1940 Disney movie {{w|Fantasia (1940 film)|''Fantasia''}} (and Disney merchandise is also almost the only place that his name is spelled as Randall spelled it, with an "a" in the middle). Because shadows are dark and the god is also dark, they cannot be seen by the refracting telescope due to the reduced light-gathering which has already been mentioned as a drawback in the main comic.

Telescopes have been the subject of [[:Category:Telescopes|many comics]] on xkcd. Recently one about space telescope was released [[1730: Starshade]] and before that a large "private" telescope was shown in [[1522: Astronomy]].

===The real problems with refracting telescopes===
The basic performance of a telescope is determined by its size: a wider telescope catches more light, making it easier to see faint objects, while a longer telescope is better for high magnification viewing. For looking at stars, the width is actually more important. No matter how much you zoom, a star is too far away to make bigger, but with a big aperture, you can see stars too faint for the naked eye. Planets benefit more from magnification, and distant galaxies need both.

In both respects, it's much easier to make a big reflector telescope than a big refractor one. Since a lens can only be held in place by its edge, the center of a large lens sags due to gravity, distorting the images it produces. This means most refractor telescopes make do with narrow apertures only a couple of inches across. Reflector telescopes are sometimes called "light buckets" because they can have extremely big openings that can catch light from even very faint stars. In addition, because it has a mirror at one end, the reflector telescope is, in effect, twice as long as it appears - a refractor just cannot compete.

Refracting telescopes were only gradually overtaken by reflecting telescopes, however. In the age of {{W|great refractors}}, the largest telescopes in the world were refractors. Reflectors at the time had mirrors surfaced in {{W|speculum metal}} that began to tarnish only months after application, negatively affecting telescope performance. This problem was resolved when it became possible to surface a mirror in silver, but the problems with refractive lenses persist. Because of this, the {{w|List of largest optical telescopes historically|largest refracting telescopes ever built}} are reflectors, rather than refractors. In addition, a {{w|liquid mirror telescope}} uses a very cheap, but potentially very large mirror - with the drawback that the telescope can only look straight upwards.

'''Randall's points:'''
*More expensive
**Grinding a high quality lens is more expensive than producing an equivalent mirror - {{w|Crown glass (optics)|crown glass}}, which is needed for good quality telescope lenses, is expensive.
*Less compact
**In theory, a refractor ''could'' be made compact, but the image quality would be awful, because the lens would have to be extremely fat. The longer the telescope is, the less dramatic the focusing needs to be.
*{{w|Chromatic aberration}}:
**In optics, chromatic aberration is an effect resulting from dispersion in which there is a failure of a lens to focus all colors to the same convergence point, producing a rainbow effect around the image familiar to people who wear glasses, and with prisms. It occurs because lenses have different refractive indices for different wavelengths of light. Each colour is therefore focused slightly differently by the lens. Mirrors don't have chromatic aberration, since the light is reflected off the front of the mirror. The {{w|achromatic lens}} can reverse this effect, but it's expensive and its size is limited. Nevertheless, before telescope mirrors were perfected in the early 20th century, the best telescopes were achromatic refractors.
***Note that this effect has also been mentioned in relation to photography by [[Black Hat]] in [[1014: Car Problems]], in a completely different context, but shows this is an issue Randall has considered before.
*Reduced light-gathering
**Apart from generally needing to be smaller than reflector telescopes a further problem comes from glass defects, striae or small air bubbles trapped within the glass. In addition, glass is opaque to certain wavelengths, and even visible light is dimmed by reflection and absorption when it crosses the air-glass interfaces and passes through the glass itself. All of this reduce the light gathered.

'''Other problems not mentioned by Randall:'''
*Suspending a lens
**Another important difference (and a big reason why large refracting telescopes don't exist) is that the lens of a refracting telescope has to be supported by the edges, so that light can pass through it. As a result there comes a point where it is no longer feasible to mount a large lens in a telescope due to its weight and the need to support it from the edges. In contrast the mirror of a reflecting telescope is supported from behind, and any support structures for the primary mirror are not in the path of the light. As a result, substantially larger mirrors can be easily mounted and supported. As an additional benefit this behind-the-mirror support has led to the creation of {{w|Adaptive_Optics|Adaptive Optics}}, a technique (which is impossible for refracting telescopes) that allows some of the atmosphere's distortions to be corrected for.
*A mirror can be segmented to make a larger reflecting surface out of smaller (and hence easier to build/mount/support) mirrors. By using a {{w|Segmented_mirror|segmented mirror}} it is possible to build an effective aperture much larger than what could be built even from a single mirror, which is itself much larger than the largest possible lens that might be built for a refracting telescope.

====The real problems with reflecting telescope====
It is worth noting that (apart from the vampire problem) reflecting telescope also has disadvantages compared to a refracting telescope:
*The main disadvantage is that in almost all reflecting telescope designs the focal point is directly in front of the mirror, i.e. in between the mirror and the target of interest.
**As a result a {{w|Secondary_mirror|secondary mirror}} is commonly used to direct the focal point somewhere outside of the field of view. However, this secondary mirror (and the struts that support it) will still block part of the field of view - although the focus of the telescope means that the secondary mirror is not visible when looking at distant objects, it will result in diffraction patterns that also hinder the image quality. In fact, this is the source of the {{w|Diffraction_spike|diffraction spikes}} around stars which are commonly seen in astronomical images.
*A reflecting telescope is also harder to maintain:
**The mirrors need to be very precisely aligned (this is called {{w|collimation}}), and this can be a laborious process. They may also need re-polishing.
**The telescope is open at one end, allowing dust and dirt to enter.
*A reflecting telescope is not very portable. This is why {{w|Birdwatching|bird-spotters}} use small refractor telescopes as an easy way to get a closer view of birds.

Despite this disadvantage, reflecting telescopes are used almost exclusively in modern astronomy because of practical limitations in making large refracting telescopes. Very few amateur astronomers use refracting telescopes - nowadays, they most exist to con people looking for Christmas presents in department stores (just because a telescope promises 100x zoom doesn't mean the image quality is any good!)

==Transcript==
:[A one panel comic showing two different telescope designs next to each other with labels above them and a bullet list of points below the them. The left drawing will be described first then the right.]

:[Left:]
:<big>Refractor</big>

:[A slim telescope design is shown. At the top the light enters shown in a light yellow shade between two thin parallel light gray lines that just fits inside the opening of the telescope which is slightly wider at the top than at the lens sitting a short way into the opening. The lens causes the light to focus just where the telescope again changes dimensions, and the light enters a small opening at the bottom of the long pipe of the telescope. Here the yellow light is a point as the two gray lines cross each other at that point. The light then broadens slightly again and the thin yellow light cone hits a mirror at the bottom of the telescope and is reflected to the left and out through the eyepiece. Below are the following points:]
:*More expensive
:*Less compact
:*Chromatic aberration
:*Reduced light-gathering

:[Right:]
:<big>Reflector</big>

:[A much broader (more than 150% of the first) but also much shorter (66%) telescope design is shown. At the top the light enters shown in a light yellow shade between two thin parallel light gray lines that still just fits inside the opening of the telescope. On it's way down to the bottom of the telescope the light passes by a small mirror turned down towards the bottom. When the hits the curved bottom mirror light is focus on it's way back back and a small light cone hits the small mirror mentioned before sitting almost at the top of the telescope. This mirror reflects the light to the left into an even thinner light cone that goes out through the eyepiece located near the top of the telescope. Below is the following point:]
:*Can't see space vampires

==Trivia==
*In an '''[http://www.explainxkcd.com/wiki/images/archive/b/b2/20170127171253%21telescopes_refractor_vs_reflector.png earlier version]''' of this comic, the eyepiece of the refracting telescope appeared to include either a mirror or a prism (possibly {{w|porro prism}} or {{w|amici roof prism}}).
**These make the image upright and allow the observer to look through the telescope from a more comfortable position.
**A mirror, however, would invalidate the only advantage it has over reflecting telescopes.
**So even though it could be said to be a prism (without the vampire problem) [[Randall]] later choose to corrected this "error" so the '''[http://www.explainxkcd.com/wiki/images/b/b2/telescopes_refractor_vs_reflector.png current/final version]''' shows the light going straight out of the end without the risk of anyone interpreting the offensive part for a mirror destroying the joke.
**Now it also looks just like one of the depictions of this type of telescopes on the Wikipedia page for the refracting telescope.
***See this {{w|Refracting_telescope#Refracting_telescope_designs|design}} that does not include a mirror/prism.

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Telescopes]]
[[Category:Rankings]]
[[Category:Science]]
[[Category:Astronomy]]
[[Category:Space]]
[[Category:Religion]]

1783: Emails

2017-01-10T19:32:43Z

162.158.150.76: /* Explanation */ some typos

{{comic
| number = 1783
| date = January 9, 2017
| title = Emails
| image = emails.png
| titletext = Hey Rob, sorry it took me a while to get back to you! Sure, I'd love to see WALL-E opening weekend! Are you still doing that, or...?
}}

==Explanation==
In this rather late [[:Category:New Year|New Year comic]] (January 9th), [[Megan]] asks [[Cueball]] if he has any {{w|New Year's resolution}}s. New Year's is, to many people, a time for thinking about the year and coming up with resolutions to improve themselves. These kind of resolutions {{w|New_Year's_resolution#Success_rate|hardly ever work}}.

Cueball replies that he has one resolution. It's to finish reading and replying to his backlog of emails from 2008, 9 years prior to this comic. He obviously does not read his email when they arrive in his inbox, and he now vows to at least get those e-mails from 9 years ago read.

As he further states in the caption below, he now (finally) begins to doubt his method for replying to e-mails, since his backlog now approaches 10 years. Some would probably say he should have found this out when his backlog approached 10 days, or at least when it reached a month.

A common technique for the ''productive'' members of the world is to batch reply to email instead of replying to each one individually as they come. The principle is that setting aside specific times to reply instead of always being "on call" gives the messages the attention they deserve while avoiding the urge to constantly check your email when you should be doing important work. Such a technique could be to check and answer all your emails once a day, or once a week, for instance and allocating a specific amount of time like one hour every day to do so. It is unlikely that somebody would wait years to start the task of checking emails, so obviously the time reserved per unit of time is way too short, if even existing. This would create a backlog of emails, that could soon be so large it would take years to catch up to the e-mail you just got right now.

Another technique for ''productive'' people is ''not'' to answer certain e-mails; if a subject really is important, the sender will send a reminder a few days later. (If he does not, the sender can be presumed to have solved the problem himself, saving lots of time on the receiver's side. Of course then you have to check your e-mails to realize if someone has sent a reminder.) Cueball has possibly used this technique on a friend's request, but became remorseful after nine years.

The title text is a reply to an email in which [[Rob]] wished to see the movie ''{{w|WALL-E}}'', a film that came out in 2008, with Cueball during its opening weekend. However, the opening weekend is now far in the past, and yet Cueball doesn't realize it and trails off with "are you still doing that, or...?" Mentioning the release of a popular movie and then making it clear that it will soon be ten years ago that the movie came out, feels a lot like a hidden [[:Category:Comics to make one feel old|Comic to make one feel old]], but it may be stretching it to include this directly in that category. But it is a technique often used by [[Randall]], quite clearly in most of that category, for instance [[891: Movie Ages]].

A real (and useful{{Citation needed}}) New Year's resolution would involve trying to answer his emails as they arrive (instead of spending any more time on years old emails), which would have avoided the mess he's currently in, and will stop it from getting worse in the future.

In this comic Cueball may represent [[Randall]]. He receives so many e-mail due to the xkcd comic that he may have a hard time going through them all. Then there is his [[what if?]] email, and possibly many more. Hopefully he has a separate e-mail for friends that wish to send him a request for going to the opening of new recent movie. On the [http://www.xkcd.com/about/ about page] on xkcd he does write the following for one of the e-mails he cites as contact:
:press @ xkcd.com -- Press questions, etc (may take a long time to get to me).

==Transcript==
:[Megan and Cueball are walking along.]
:Megan: Did you have any New Year's Resolutions?
:Cueball: Gonna finally finish dealing with those emails from 2008.

:[Caption below the panel:]
:As my email backlog approaches 10 years, I'm starting to have doubts about my approach.

{{comic discussion}}

[[Category:New Year]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Rob]]

1783: Emails

2017-01-09T16:53:16Z

162.158.150.76: /* Explanation */

687: Dimensional Analysis

2017-01-09T13:45:05Z

162.158.150.76: /* Some numbers for this calculation */

{{comic
| number = 687
| date = January 11, 2010
| title = Dimensional Analysis
| image = dimensional_analysis.png
| titletext = Or the pressure at the Earth's core will rise slightly.
}}

==Explanation==
Cueball has a [[My Hobby|hobby]] — showing correct calculations according to the {{w|dimensional analysis}} — but with ridiculous correlations of uncorrelated events and measurements. Here Cueball is teaching a class and uses this trick to ''convince'' his students that the {{w|Toyota Prius}} combined {{w|United States Environmental Protection Agency|EPA}} gas mileage is somehow connected to the constant ''{{W|Pi|π}}'' via the {{w|Planck energy}}, the pressure at the {{w|Inner_core|earth's core}} and the width of the {{w|English Channel}}.

Scientists — often physicists — use dimensional analysis to quickly check if a given formula can possibly relate to a physical system, because if you end up with an equation claiming that joules are meters, something is clearly wrong. Dimensional analysis here refers to the check if both sides of the equation arrive at the same physical unit when the units of all variables get plugged into the equation. This requires knowledge of the system of units and the relation between different physical units.

Cueball uses the following equation to make a mockery of the practice:

(Planck energy) / (Pressure at the core of the earth) * (Prius combined EPA gas mileage) / (minimum width of the English Channel) = π

===Dimensional analysis===
The right hand side is dimensionless, it's the constant ''π'' = 3.14... which is defined by the relation of two lengths, the circumference and the diameter of a circle. The left hand side requires to plug in the dimensions of the named physical quantities:

*Planck energy: given in Joules [J]
*Pressure at the core of the earth: Given in Pascals [Pa]
*Prius combined EPA gas mileage: gallons/mile, cubic meters/meter [l/m]
**Fuel efficiency has two formats that are commonly used: length/volume and volume/length. The former must be used here in order to get the units to cancel correctly.
*minimum width of the English channel: meters [m]

When plugged into the left hand side this amounts to:

[(J / Pa) * ((m/l) / m)] = [(Nm / (N/m²)) * ((m/m³) / m)] = 1

Using the following unit relations (this does not reduce units to the seven SI units, but does use some derived units):

*1 Joule = 1 Newton-meter [J] = [Nm]
*1 Pascal = 1 Newton per square-meter [Pa] = [N/m²]
*1 cubic-metre = 1000 litres [m³] = 1000 [l]

Note that for dimensional analysis constant factors are not taken into account. Here square brackets are used to denote dimensional analysis. In the above equation the unit of force (newton) as well as all the units of length (meter) cancel out each other.

Another aspect of the comic is, that sometimes dimension analysis of equations that were not derived but rather "made up" can provide insight. However, in reality such an equations would have to be somehow "motivated", which is more of an art than science and requires great experience in the field the equation should relate to. The presented equation combines values that have no immediate causal relation with each other, so it does not make sense. Furthermore, since the values have absolutely no causal relation to each other, the ratios presented are simple coincidence; despite Cueball's claim, building a better Prius would not cause any changes to the English Channel.

The title text also refers to this, as a higher pressure at Earth's core could also balance the equation, keeping the result constant equal to ''π''. The Planck energy is an absolute, however, so it is not mentioned as a way to balance the next version of Prius.

===Some numbers for this calculation===
The {{w|Planck energy}} is the only nearly exact value we do have. Compared to other Planck values it is very large (macroscopic).
E_planck = 1.956 x 109 J = 1.956 x 109 Nm

Pressure at the {{w|Inner_core#Temperature_and_pressure|core}} of the earth ranges from 330 to 360 gigapascals.
Using a simple value like this:
P_core = 350 GPa = 3.5 x 1011 N/m²

Prius combined {{w|Toyota_Prius#Fuel_economy_and_emissions|EPA gas mileage}}:
For the third generation (from 2010) the City mileage is 51 mpg and the Highway mileage is 48 mpg. But it is the [http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=26425 combined EPA gas mileage] which is used in the equation and that is 50 mpg.
50 mpg => 13.2 miles per litre => 21,000,000 meter per m³

Minimum width of the {{w|English Channel}} is about
33.1 km or 33,100 meters.

Calculating from these values you will get ''π'' = 3.54... that is pretty close to ''π'' = 3.14... while using a Planck value. According to Cueball this will be within the experimental error (the combined error for all four numbers - none are exact numbers). For instance if you tried the ePrius you would probably get closer to that target — as the mileage in real life usually is somewhat lower than the value given — and that would reduce the result.

[http://www.wolframalpha.com/input/?i=%28Planck+Energy%29%2F%28Pressure+at+the+earth%27s+core%29*%28Prius+combined+EPA+Gas+Mileage%29%2F%2833.1+km%29 Wolfram|Alpha can find most of the statistics and do the calculations.]

=== Trivia ===
This definition of pi uses, among other values, the width of the English channel. Incidentally, an approximation of pi can be found using natural water bodies: The sinuousity of a freely meandering river approaches pi. The {{w|sinuousity}} is the ratio of the true length (as the water flows) and the straight line, from river source to river delta.[https://www.theguardian.com/science/alexs-adventures-in-numberland/2015/mar/14/pi-day-2015-pi-rivers-truth-grime]

==Transcript==
:My Hobby:
:Abusing dimensional analysis

:[On a blackboard.]
:(Planck energy/Pressure at the Earth's core) x (Prius combined EPA gas mileage/Minimum width of the English Channel) = π

:[Cueball indicates this equation with a pointer in front of a class.]
:Cueball: It's correct to within experimental error, and the units check out. It must be a fundamental law.
:Student: But what if they build a better Prius?
:Cueball: ''Then England will drift out to sea.''

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics with color]]
[[Category:Comics with inverted brightness]]
[[Category:My Hobby]]

1783: Emails

2017-01-09T13:27:41Z

162.158.150.76: /* Explanation */

1597: Git

2016-12-15T22:46:06Z

162.158.150.76: /* Explanation */ this comic is referenced on a What If error page

{{comic
| number = 1597
| date = October 30, 2015
| title = Git
| image = git.png
| titletext = If that doesn't fix it, git.txt contains the phone number of a friend of mine who understands git. Just wait through a few minutes of 'It's really pretty simple, just think of branches as...' and eventually you'll learn the commands that will fix everything.
}}

==Explanation==
===This is Git===
{{w|Git (software)|Git}} is a version control system, used to manage the code in many millions of software projects. It is very powerful, and was amongst the first widely adopted tools to use a distributed version control model (the "beautiful [https://en.wikipedia.org/wiki/Graph_theory graph theory] [https://en.wikipedia.org/wiki/Tree_(graph_theory) tree model]"), meaning that there is no single central repository of code. Instead, users share code back and forth to synchronise their repositories, and it is up to each project to define processes and procedures for managing the flow of changes into a stable software product.

===How do we use it?===
Although very powerful, the command line of Git is notoriously difficult to learn and master. Dozens of blog posts and websites (see [http://think-like-a-git.net/epic.html], [http://stevebennett.me/2012/02/24/10-things-i-hate-about-git/]), and even books ([http://blog.anvard.org/conversational-git/chapter-01.html], [http://git-scm.com/book/en/v2]) have been written to help users navigate this complexity.

The difficulty of using Git in common situations is belied by the apparent simplicity of its use in tutorial-style situations. Committing and sharing changes is fairly straightforward, for instance, but recovering from situations such as accidental commits, pushes or bad merges is difficult without a solid understanding of the rather large and complex conceptual model. For instance, three of the top five highest voted questions on Stack Overflow are questions about how to carry out relatively simple tasks: undoing the last commit, changing the last commit message, and deleting a remote branch.

This comic thus explores the difference between the idealised view of Git's architecture, and its actual typical usage. Tutorials for Git tend to use simple systems in their examples, and only deal with the most basic commands to get started, which can create the misleading impression that Git can be used effectively without extensive study.

Due to this problem, compounded by the fact that Git's commands are named differently from similar commands in other version control systems, many users (including Cueball) are unable to use it beyond basic commands, and might try to avoid problems by saving their code outside Git, downloading a newer copy, and then re-applying their changes to the new copy instead of trying to understand and use the features that exist in Git to accomplish this task.

===Memorize these shell commands===
Cueball suggests "just memoriz[ing] these shell commands and type them to sync up". He is probably referring to a sequence of commands such as:

git pull
# remote changes have now been received, so work on your file
git add file.txt
git commit -m "Added some text"
git push

===If you get errors...===
As long as every contributor to the project follows these principles, this may suffice for a while. But many situations may cause "errors":

* merge conflicts (two people editing the same part of the same file)
* unmerged changes (another person committed a change before you did, so you need to merge their changes first)
* attempting to recover from a situation such as an accidental merge, and making the situation worse.

In a situation such as a merge conflict, Git will show an error message such as:

CONFLICT (modify/delete): README.md deleted in HEAD and modified in branch-b. Version branch-b of README.md left in tree.
# Automatic merge failed; fix conflicts and then commit the result.

===Save your work elsewhere...===
Although Git experts can of course deal with such situations, the remedy proposed by Cueball is "save your work elsewhere, delete the project, and download a fresh copy". That is, to copy the files out of their local repository's working directory, delete that whole structure, then clone the remote repository again (and, implicitly, copy the saved work back again):

# Copy files elsewhere
mkdir /tmp/myproject
cp * /tmp/myproject
cd ..
# delete the project
rm -rf myproject

# Download a fresh copy
git clone https://github.com/myorg/myproject
cd myproject

# Copy saved work
cp /tmp/myproject/* .

Abandoning the old project likely means losing some work, but may be faster and give a more predictable outcome than attempting to salvage the situation. Applying this method to a mere merge conflict issue may prolong the issue however, as the merge conflicts may still be present.

===Title text===
The title text suggests an alternative method for working around Git's complexities, which reflects common practice: knowing a "Git expert" who can help in any situation. Such experts are somewhat notorious for waxing lyrically about Git's strengths, so it may be necessary to win their favour by first letting them ramble enthusiastically about it. They will hopefully eventually give the exact commands needed. In practice, the question-and-answer site Stack Overflow is frequently used for this exact purpose.

It may even be a reference to the infamous tweet "[https://twitter.com/agnoster/status/44636629423497217 Git gets easier once you get the basic idea that branches are homeomorphic endofunctors mapping submanifolds of a Hilbert space]" which has been [http://www.beyondjava.net/blog/git-explained-in-really-simple-words/ discussed here] but it is inconclusive whether a meaningful interpretation exists.

Putting a telephone number of someone who "understands Git" into such a file is humorous because:
*Software teams would more normally use electronic means of communication
*Explaining Git over the phone to team members should not be necessary, as there is extensive help available online, and
*In the situation where many team members would need phone support to avoid or fix basic Git problems, this would be extremely distracting to the person whose phone number was given in the file.

=== TL;DR===
In short: programmers use {{w|Version control|version control systems}} to track changes to code. Most of these version control systems are quite similar and easy to learn if you already know another one. Git is a version control system based on completely different principles, and most programmers find it difficult to wrap their heads around it (although Git also offers a large number of nontrivial benefits over standard version control systems, which is why it is used). Cueball is one of those programmers.

This comic is referenced on https://what-if.xkcd.com/153/, the page where Randall, due to a problem with git, erroneously posted a draft of his "What If?" piece on peptides. As of December 15th, 2016 the page reads:

''Whoops''
''This article is still in progress. An early draft was unintentionally posted here thanks to Randall's troubled approach to [[Git|git]], and it took a little bit to get everything sorted out and rolled back. Sorry for the mixup!''

The comic [[1296: Git Commit]] also features Git.

==Transcript==
:[Cueball points to a computer on a desk while Ponytail and Hairy are standing further away behind an office chair.]
:Cueball: This is git. It tracks collaborative work on projects through a beautiful distributed graph theory tree model.
:Ponytail: Cool. How do we use it?
:Cueball: No idea. Just memorize these shell commands and type them to sync up. If you get errors, save your work elsewhere, delete the project, and download a fresh copy.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Programming]]
[[Category:Computers]]
[[Category:Internet]]