explain xkcd - User contributions [en]

2466: In Your Classroom

2021-05-22T09:28:58Z

108.162.219.134:

{{comic
| number = 2466
| date = May 21, 2021
| title = In Your Classroom
| image = in_your_classroom.png
| titletext = Ontology is way off to the left and geography is way off to the right.
}}

==Explanation==
{{incomplete|Created by a QUASAR IN YOUR CLASSROOM. The table is still a work in progress. Do NOT delete this tag too soon.}}
Randall has created a thought experiment and corresponding chart about school courses. The idea is, "the subject of the class appears in the classroom" and the chart compares how dangerous and how unusual that would be.

{| class="wikitable"
|+Breakdown of Subjects
|-
!Course Topic
!Weirdness
!Danger
!Explanation
|-

!scope=row|Atmospheric Physics
|0%
|0%
|The presence of atmosphere in the classroom is quite common, as humans require the presence of an atmosphere to remain alive, and cannot learn while dead.{{Citation needed}}
|-

!scope=row|Ethics
|25%
|0%
|Ethical thinking and behavior are widely considered good and should normally be present in education, but are sadly not universal.
|-

!scope=row|Education
|0%
|10%
|Learning usually goes on in classrooms, so education as a concept is both being learned about and present in the form of learning itself.
|-

!scope=row|Bibliography
|25%
|7%
|Bibliography is the study of books, and books are normally present in classrooms, particularly bibliography classrooms.
|-

!scope=row|Human Physiology
|0%
|20%
|This comic assumes that there are humans learning in the classroom, which was true at the time this comic was published. However, as of 2038 the Earth has been overtaken and education is forbidden for mere mortals.{{Actual citation needed}}
|-

!scope=row|Public Speaking
|25%
|15%
|Some classes require students to present things in front of the class, which is likely a requirement in a public speaking class. Thus, public speaking itself would be present in the class.
Some classes also have a teacher talking or presenting to the students from the front of the class, another form of public speaking.
|-

!scope=row|Architecture
|0%
|30%
|All buildings can be considered architecture, and most classes take place in buildings. This comic also refers to a class''room'', which is a room, and therefore considered architecture.
|-

!scope=row|Library Science
|25%
|25%
|Library science is concerned with the organization of knowledge, and is useful for finding information. Many classes require research papers that require the use of books and other sources of information to complete them.
|-

!scope=row|Furniture Design
|0%
|40%
|Most rooms have furniture,{{Citation needed}} so this would probably be present in a classroom
|-

!scope=row|Culinary Arts
|40%
|30%
|Most studies of culinary arts include the teacher and/or students preparing food using the tools and/or techniques that have been taught, so it would be fairly normal for food to be a result of classroom activities. How ''good'' it is, however, can be a mixed bag, especially for student cooking attempts.
|-

!scope=row|Ergonomics
|5%
|45%
|Ergonomic equipment and workspaces promote comfort and efficiency, while non-ergonomic ones may be unpleasant, unhealthy, or even immediately dangerous.
|-

!scope=row|Botany
|40%
|40%
|The near-neutral position of Botany (aka Plant Biology) obscures a wide range of possible outcomes, from the banal to the malignant. A teacher might have brought in a potted plant for decoration or show-n-tell, which would have zero weirdness and (if a non-allergenic species) zero danger. Or, a tree might have fallen through the roof, highly dangerous and weird, especially if it occurred during calm weather (weather likely to result in trees falling would probably have closed the school prior to treefall). This assumes that the event involves a vegetable and not an element of consumerism or purchasing.
|-

!scope=row|20th Century Authors
|65%
|10%
|A literature class would, normally, benefit greatly from an open discussion or interview with the author himself. Sadly such things are rare. Authors who were published in the 20th century would mostly be in retirement age in 2021, so securing an interview with them could be somewhat difficult.
|-

!scope=row|Exobiology
|100%
|0%
|Exobiology is the study of extraterrestrial life. This would mean that an alien life-form was in the classroom.
|-

!scope=row|21st Century Authors
|60%
|20%
|21st century authors have the advantage (over 19th and 20th century authors) of being alive and active at the time this comic was published. However, few of those born during the century have had time to achieve professional success, while those who have published in the 21st century mostly await final literary judgement on their work. Those authors with sufficient notoriety to be welcome in a classroom might charge appearance fees that schools cannot afford, and might, regardless of money, only agree to appear via virtual conference - hence, an elevated weirdness score. Dangers of an actual physical appearance include COVID risk and possible clashes between an author's activist stance and school policies.
|-

!scope=row|19th Century Authors
|100%
|15%
|Like other authors, the class would benefit from having an actual author show up, but this would be extremely weird since no 19th century author is still alive.
|-

!scope=row|Paleontology
|100%
|25%
|Paleontology is the study of fossils. It would be normal to have some fossils in the classroom, so Randall is probably implying the weirdness of finding a live dinosaur.
|-

!scope=row|Robotics
|55%
|30%
|A course on robotics would often be expected to have some form of working models of the robots being discussed.
|-

!scope=row|Martian Soil Chemistry
|100%
|35%
|Martian soil only reaches Earth in small amounts, so it would be unusual to find a meaningful amount anywhere.
|-

!scope=row|Tourism
|75%
|40%
|Tourists coming into an active classroom would be quite unusual. It could refer to the students leaving to become tourists in another location.
|-

!scope=row|Child Psychology
|60%
|45%
|
|-

!scope=row|Entomology
|15%
|55%
|Insects in the classroom.
|-

!scope=row|Occupational Therapy
|10%
|62%
|Injury, illness or mental health problem that hinder your participation in life/school. Many students who have significant physical injuries and conditions that require occupational therapy would generally not engage in those activities during a class.
|-

!scope=row|Hydraulic Engineering
|40%
|62%
|Likely in the form of flooding or plumbing problems.
|-

!scope=row|Pest Control
|25%
|70%
|
|-

!scope=row|Foodborne Illness
|15%
|80%
|Sometimes students in a culinary arts class do not properly observe hygiene standards and the food they present would lead to illness in those that consume the food. Thankfully, this is rare if the teacher is paying enough attention to proceedings. Students could also be ill from food eaten outside of class.
|-

!scope=row|Criminal Law
|45%
|85%
|This might happen if a crime occurs in the class.
|-

!scope=row|Physiology of Stress
|0%
|90%
|This would be a sign of stress severe enough to affect bodily functions, likely to an unhealthy extent.
|-

!scope=row|Oncology
|25%
|100%
|Someone in the room likely has cancer.
|-

!scope=row|Ornithology
|60%
|55%
|Birds in the classroom?
|-

!scope=row|Animation
|100%
|56%
|Examples of animated works might be displayed to the students in an animation class.
|-

!scope=row|Petroleum Geology
|65%
|60%
|Crude oil coming up through the floor of the classroom would be ''very'' weird.
|-

!scope=row|Highway Engineering
|75%
|65%
|A highway being built through an active classroom would be very unusual and not that safe.
|-

!scope=row|Toxicology
|55%
|75%
|Someone in the room has been exposed to a toxic substance.
|-

!scope=row|Hematology
|75%
|70%
|Hematology is the study of blood. Given that there should be blood in each of the students present{{Citation needed}}, we should probably assume Randall means "large quantities of blood outside of one's body", which would indeed be both bad and weird.
|-

!scope=row|Hostage Negotiation
|70%
|85%
|Reasons as to why there would be hostage negotiations taking place at a school have horrifying implications for the students and teacher.
|-

!scope=row|History of Siege Warfare
|100%
|80%
|This would mean that the students would be trapped in the building until they ran out of resources, possibly dying of thirst and starvation (depending on whether or not the opposing army destroyed the school's water lines).
|-

!scope=row|Trauma Surgery
|55%
|95%
|Trauma surgery is an incredibly painful procedure, and difficult to look at for many. It would undoubtedly be disturbing to the class, especially if the patient was one of them.
|-

!scope=row|Volcanology
|75%
|95%
|Having a live volcano in one's classroom is both very dangerous and very weird, as volcanoes take very long times to form. Note this also applies to [[1611: Baking Soda and Vinegar | baking soda and vinegar volcanoes that are offshoots of much larger vinegar hotspots]].
|-

!scope=row|Quasar Astronomy
|75%
|100%
|Quasars are distant astronomical objects that release large amounts of energy. Not only would the power of a quasar destroy the classroom (as well as the building the classroom is in, the town the school is in, and the entire planet Earth,) quasars are too large to fit inside any known classroom. For example, [ULAS J1342+0928](https://en.wikipedia.org/wiki/ULAS_J1342%2B0928) has a mass of 8*10^8 solar masses. This means the event horizon of the black hole is almost 16 AU in radius, and this size does not include the accretion disk.
|-

!scope=row|Ontology (Title Text)
|<0%
|?
|Ontology is the philosophical study of existence and being. Since there must be ''something'' learning in the classroom, it is unsurprising that ontology is a normal subject to appear in the classroom.
|-

!scope=row|Geography (Title Text)
|>100%
|?
|Logistics aside, having a planet's terrain newly appear in one's classroom would almost certainly be a distraction to the learning environment.

|}

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Caption above scatter plot with labeled axes]
:Caption: The thing you study just showed up in your classroom! That's...
:Upper y-axis label: Good
:Lower y-axis label: Bad
:Upper x-axis label: Normal
:Lower x-axis label: Weird

:[First quadrant (left to right, top to bottom):]
:20th century authors
:Exobiology
:21st century authors
:19th century authors
:Robotics
:Paleontology
:Martian soil chemistry
:Child psychology
:Tourism
:[Second quadrant]
:Atmospheric physics
:Ethics
:Education
:Bibliography
:Human physiology
:Public speaking
:Architecture
:Library science
:Furniture design
:Culinary arts
:Ergonomics
:Botany
:[Third quadrant]
:Entomology
:Occupational therapy
:Hydraulic engineering
:Pest control
:Foodborne illness
:Criminal law
:Physiology of stress
:Oncology
:[Fourth quadrant]
:Ornithology
:Animation
:Petroleum geology
:Highway engineering
:Toxicology
:Hematology
:Hostage negotiation
:History of siege warfare
:Trauma surgery
:Volcanology
:Quasar astronomy

{{comic discussion}}
[[Category:Charts]]

Talk:2363: Message Boards

2020-09-24T18:21:12Z

108.162.219.134: Gen x

Randall stimulates people doing this to their parents? [[Special:Contributions/108.162.219.234|108.162.219.234]] 01:23, 24 September 2020 (UTC)
:He doesn't necessarily think it's likely. But as the caption says, he's amused by the fact that it's possible because the Internet and message boards have been around long enough. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 02:04, 24 September 2020 (UTC)

It would be interesting to know how many online message boards have actually been in continuous operation for 20 years. The original Usenet newsgroups are actually twice that old, but what about Internet boards? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 02:04, 24 September 2020 (UTC)
:Reddit is starting to get there, being 15 years old now. I also do know some forums that started in 2003~2004 and are still active (mostly ones tied to still-updating webcomics). So not quite 20 years, but close. --[[User:Elifia|Elifia]] ([[User talk:Elifia|talk]]) 03:04, 24 September 2020 (UTC)
::There'll be BBSes (one I once used is still going, last I checked, well over 30 years old, pre-Web, not sure how many old-guard are there, as I've not for 25 years) and that would rival even pre-split Usenet. A MUD I know (all my characters long timed-out) is still going strong since pre-Web times, too. IRC isn't exactly persistent (and has changed a lot) but still exists. Even if the likes of anon.penet.fi have been closed, there'll be mailer-gateways/request-by-mail things (I used to ask one for Freeware!) on obscure servers. Perhaps Wollongong University still has a Gopher server (one memorable 'place' I visited on a link-to-link round the world trip, back just before I heard of the Berners-Lee thing). I have a habit of forgetting webforums (earliest currently used one was signed into only back in 2008) and a late-'90s one I recall fondly got so spammed (despite whatever passed for CAPTCHA in those days) that the webmaster Read-Onlied it, and domain is now expired. If I was a better person at staying in touch, I'm sure I could have been continuously active for sufficient time on a single platform (I fell off a Usenet group when I lost a newsfeed and refused to use the then-new-fangled Google Groups interface, just the latest insult since WebTV, the push from AOL and the whole Eternal September thing). So, anecdotally, I know there's a good chance. [[Special:Contributions/162.158.159.34|162.158.159.34]] 03:42, 24 September 2020 (UTC)
:I have been an active member at GameFAQs.com for longer than 20 years. The message boards there opened in 1999.[[Special:Contributions/173.245.52.169|173.245.52.169]] 04:23, 24 September 2020 (UTC)

With a name like NIN85, I bet Mom is a Nine Inch Nails fan. ❤️ [[Special:Contributions/172.69.35.61|172.69.35.61]]

== Too dumb for this one ==

Is it just me or was the detail the whole joke hinged on a bit more subtle than usual here? Sure, sometimes it's arcane, but I feel like you don't usually need to read between the lines so much to even get the backstory for the joke.

On first read, obviously the two characters know each other, and the fact that a real life acquaintance would reply to a 20yo thread was clearly part of the joke. But essentially I read this as two people complaining about the same thing, as one often does on message boards. By the time I put it together that "NIN85 must be older now" + "new user from context is a teenager" + "most adults don't know many teenagers" + "except they do know their kids" = "she's talking to her kid", it was far too late for me to get the laugh. In retrospect "we talked about this" is a classic parenting line, but given that one tends to talk to many people about many things, it didn't really point me in that direction the way it was probably intended.

Maybe, not being a parent myself, my instincts also led me to assume that an older person would still sympathize and support a young person in search of totally rad transportation, rather than shooting them down like her mother before her :P So the assumption that "we talked about this" = "I, Vespa fan, have already denied you the same privilege" seemed like an especially great leap!

So, probably just having a slow brain day, but is there anything else to it I'm missing? Also, does Randall have kids? [[User:Jerodast|- jerodast]] ([[User talk:Jerodast|talk]]) 04:55, 24 September 2020 (UTC)
:Not just you. It took me a while before I noticed the dates on the posts, but then I put it all together. Maybe a better title for the comic would have helped, something including "necro". [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 05:54, 24 September 2020 (UTC)
:Reconstructing my own first reading of this (before I slept last night so imperfect) it seems I read the post-text first, worked out it was a mom/son relationship, 'confirmed' by finally reading the posting dates (the point at which I probably belly-laughed for 'getting it'), spotted the "New User" subtly there in the side-profile and then (after noting the forum name, subtitlr, title-text, etc) wondered about the Profile Pic.
:Mom seems to have kept (or deliberately retroed) an image from her youth, even if not the original (if there was any, for the v1.0 forum layout to show) pic uploaded in 2000. This was pre smart-phone/selfies, to any reasonable degree. Is this a scan of of an old emulsion photo? (It also has possible photoshopping artefacts of portrait over new background, by one reading of it.) Would a more worldwise 25yo scan in and upload a pic of her 15yo self? Maybe in a "see, I ''was'' there at Woodstock" way (though not actual Woodstock, unless that's the photoshopped background - or something like that - but maybe still not with a 15yo 'selfie' shot, but something from a later age). It's at this point I'm thinking I'm overthinking this (especially given how much 'exposure' many people still give in the profiles and avatars, even 35yo moms), especially given I've never used a selfie-avatar at all. [[Special:Contributions/162.158.159.116|162.158.159.116]] 12:14, 24 September 2020 (UTC)
::If you change your profile picture it will change for any post made. That's at least true for all fora I'm member of. Why would each individual post contain the information of which profile picture was active at the time the post was made (plus the actual picture data)? So there's no indication if the picture shown here is "teen mom" or "adult mom" (or "mom" at all). [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 12:31, 24 September 2020 (UTC)
:::I know that, and it was on this basis that I presumed its likely a later (though who knows how recent) scan of an earlier physical photo. (Because that clearly looks more like a Randall-girl than a Randall-mom, in Cueball-People style, notwithstanding how in RL™ younger people often attempt to look older and vice-versa.) [[Special:Contributions/141.101.98.98|141.101.98.98]] 15:06, 24 September 2020 (UTC)
:::: In that case, how do you come to the conclusion that the profile picture shown there is a "young" person? By the hairstyle or what? I don't get it. [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 15:18, 24 September 2020 (UTC)
:::::Yes. Young hair (as opposed to young-adult hair, then eventually the tied-up bun look that can also mean 'serious' but with ornamentation). It's just my impression. Also note that Julz seems to favour the 'studio background' look (maybe filter-cropped down to just the head and shoulders) while NIN85 favours the more passive "visit to a place" photo that is ''not'' obviously a selfie, a height-shot, a posed sunrise/set one, which (the possibilities of photoshopping apart, due to the hint-of-border actually probably only there to maintain contrast between hair and the darker bit of the background) puts it in an early age of photography tropes. In my mind, but obviously not yours.
:::::But on the basis that every drawn feature is deliberately put there (rather than various accidents of setting in actual images of real life) [[1401|I like to think]] it's deliberately setting up the trope of a historic photo of young-millenial (''meant'' to be from roughly the time of the opening post, but probably uploaded much later) vs a more current pose by a young-post-millenial. YMMV.
:::::And none of this is a complaint, just a recollection of what I was originally pondering, as I appreciated the comic. Probably taking up no more than a minute of my time, last night, and now I'm surprised it's taking up this much more of it for both of us... ;) [[Special:Contributions/141.101.98.98|141.101.98.98]] 16:09, 24 September 2020 (UTC)

She’s would be a closer to a gen-xer [[Special:Contributions/108.162.219.134|108.162.219.134]] 18:21, 24 September 2020 (UTC)

Another in-joke is that Vespa is a scooter and there is an electric model [https://elettrica.vespa.com/en/index.php] that require either a moped license or a full motorcycle license, depending on the engine power, that is a premium model, Peugeot electric scooter cost 40% less, for instance.
[[Special:Contributions/162.158.94.200|162.158.94.200]] 07:13, 24 September 2020 (UTC)

2362: Volcano Dinosaur

2020-09-23T13:38:06Z

108.162.219.134: {{Citation needed}}

{{comic
| number = 2362
| date = September 21, 2020
| title = Volcano Dinosaur
| image = volcano_dinosaur.png
| titletext = Phylogeneticists are working on identifying and notifying its next of kin.
}}

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

This comic is a reference to [https://www.independent.co.uk/news/world/asia/new-dinosaur-discovered-china-volcano-b511774.html this discovery] of [https://peerj.com/articles/9832/ fossils of dinosaurs that were buried and killed by a volcanic eruption].

Facetiously, Megan asks if the dinosaur was okay. As living things typically don't survive being fossilized in volcano debris{{Citation needed}}, the answer to the question would obviously be "no", but Cueball replies that he is unsure. Even if the dinosaur somehow survived the initial burial, it would be very difficult for it to survive buried for 125 million years. 2020 wouldn't probably be the best year to dig it up and potentially let it free.

Megan's response is natural and expected in many situations when hearing of a person or creature experiencing misfortune. The humour here comes from the inaptness of asking the question millions of years after the event. Rather than responding to the ridiculousness of Megan's question, Cueball takes it seriously, and deadpans that he can't tell.

The title text suggests contacting its "{{w|next of kin}}", which usually means a nearest living relative, e.g. a brother or a sister. The process of identifying and contacting next of kin is a standard step performed by authorities in the event of a death being discovered. In this case, dinosaurs are extinct{{Citation needed}}, so it is the job of {{w|Phylogenetics|phylogeneticist}}s (those who study evolutionary relationships) to determine which living animal (presumably a bird of some kind) is the "nearest relative" to the deceased dinosaurs.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Megan is standing facing right, talking to Cueball who is sitting at a computer desk and also facing right, looking at a computer screen.]
:Cueball: Oh cool, they just found a dinosaur that was buried by a volcanic eruption 125 million years ago.
:Megan: Wow.

:[Pause. Megan is still facing right. Panel closes in on Megan and Cueball is not shown. This panel has no dialogue.]

:[Megan has stepped closer to Cueball, who is still looking at the screen.]
:Megan: Was it okay?
:Cueball: Hmm, it doesn't say.

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

Talk:1441: Turnabout

2014-11-03T21:37:28Z

108.162.219.134:

In the few seconds the photons take to get to the moon and back, the earth has moved enough on its axis that the reflected beam from a perfect retroreflector is not gonna hit the protagonist.

The retroreflectors for the Apollo missions were deliberately spoiled so they return six slightly offset beams, angled such that photons from one of them will go back near enough to the source.

Oh, and of course there's also the whole r^4 thing too. {{unsigned ip|‎108.162.250.208}}
:Citation needed. And did you mean the inverse square law? [[Special:Contributions/103.22.201.195|103.22.201.195]] 07:37, 31 October 2014 (UTC)
:Since you acknowledge that the reflectors for the Apollo missions were constructed to take this into consideration and the photons will return near enough to the source, the cartoon is still valid. Now, whether the photons would retain sufficient energy upon their return to cause harm when they did not have enough power to destroy the reflector in the first place is a subject for another discussion .[[Special:Contributions/108.162.216.94|108.162.216.94]] 07:49, 31 October 2014 (UTC)
::The photons will retain the same power (more or less...), but there will be less ''of'' them. The laser (e.g. the one from the Apache Point observatory) spreads out on its way to the Moon (perfect collumation into a millimetre-wide laser beam is neither practical nor desirable, given the need to 'flood' the vicinity of the reflector in leiu of impossible accuracy, including to account for asymmetric atmospheric distortion on the beam and its return) so that only a small proportion of the beam hits a reflector unit (one of the largest being 0.6m²) and the returning beam (for reasons already mentioned) is again much wider than the collecting telescope (3.5m diameter, possibly). There's usually no more than a dozen photons (per each short pulse of the laser) that actually make the return trip to be detected, and often it's well down into single-figures, requiring many such pulses to gather enough photons to make a statistically significant analysis.
::All this, of course, does render even more ridiculous the concept of manually firing even a ''combat''-strength laser beam across the necessary void and back again to such a precise hit (and, BTW, the What-If someone was mentioning is http://what-if.xkcd.com/13/ and shows a possibly less-tightly-collumated-than-Apache-Point laser having a diameter of almost half that of the Moon itself). But what the hey? ;) [[Special:Contributions/141.101.99.112|141.101.99.112]] 10:04, 31 October 2014 (UTC)

Superimposing the 3rd and 5th panels over each another shows the beam does not come back exactly to its source
http://xbehome.com/uploads/retroreflector.png [[User:Defaultdotxbe|Defaultdotxbe]] ([[User talk:Defaultdotxbe|talk]]) 08:09, 31 October 2014 (UTC)

Can anyone comment on how likely/unlikely it would be to accidently hit a retroreflector on the moon? The moon takes up only a very small proportion of the sky (when visible at all of course), and so the likelyhood of that wild shot even hitting the moon at all has to be pretty low. (I'm sure there was a What-If on this...) --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 09:22, 31 October 2014 (UTC)

:: Randall covered lasers hitting the moon in [https://what-if.xkcd.com/13/ what-if 13] --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 09:45, 31 October 2014 (UTC)

What is a 'reflective' palindromic number like mentioned in an (early?) version of this explanation:
:Citation: "It is worth noting that the number of this comic is 1441: a 'reflective' palindromic number."
All I could find about reflective ~palindromes was that you should be able to mirror the number/word and still get the same. But you cannot mirror 4 into 4. So in that way it cannot be reflective... (1 maybe if the font is the correct one, else only 8 and 0 in numbers and some letters like A and X).
Of course it is a palindrome as it would read 1 4 4 1, also in reverse. But reflective - not so much?
If it is not reflective, then it has no relevance in the explain as it was this reflection that had a reference to the story... [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 10:49, 31 October 2014 (UTC)
What

:I agree, the number is a palindrome, but not a reflective palindrome. I'm not quite decided on whether the fact it is a palindrome holds any relevance, or is simply a coincidence. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 11:10, 31 October 2014 (UTC)

I've removed a sentence about "continuity problems" and why the beam does not go right through the opponent (or hit the original shooter). No laser tag set that I know of is powerful enough to go right through someone, I imagine that would be regarded as a slight health & safety issue. You could argue that panel 1 shows the beam going through someone, but I think that is in fact behind him. As far as him being knocked over, I would guess that is to emphasise his being hit, rather than physically knocked over. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 13:35, 31 October 2014 (UTC)
:IMO, it's not laser-tag at all, but a full-strength offensive laser-blast (of at least 'stun' level). The first 'through the body' shot is actually a miss 'in depth' (rarely for XKCD comics without other explicit perspective cues to the image, like this one, it's in the <TwilightZoneMusic+Reverb>Third! Dimension!</TwilightZoneMusic+Reverb>...), neither harming nor impeded by the attacker. The rebounded shot at the end appears to have at least caused the same attacker to lose grip of his gun, if not caused physical damage to his back. (Although I suppose he could be wearing a "shocker" or vibrating-on-hit style of laser-tag kit, or is reacting to the sound-effect arising from the unexpected "hit detection".) No doubt a combat-level laser would be dialled up to damage your target without ''necessarily'' burning straight through.
:Also (regarding another comment), while I imagine it'd be useful to wear armour designed to be reflective (or even retroreflective!) all over, it would probably be impractical, whereas the lunar retroreflector array being used might possibly itself withstand the beam for at least long enough to get a decent amount of bounce-back. Anyhow, with such Improbable Aiming Skills, I suspect at least latent and subconcious Force abilities were in play, which can handwave all such niggling problems. Right guys? (And also opens the doorway for this being a universe with full-on Stormtrooper Armour... you know, the kind that's Reactive Armour, but assembled the wrong way round so it ends up hurting you more than if you were wearing no more than woven and leather fabrics...) [[Special:Contributions/141.101.99.112|141.101.99.112]] 14:24, 31 October 2014 (UTC)

As the earth is turning, the reflected beam would hit different spot. In that 2.5 secs it would take the beam to travel back to the earth, earth would have turned 1.160km at the equator. So even if the beam would stay collimated the beam would miss coming back. {{unsigned ip|173.245.51.196}}

Clearly black-hat stole an apollo reteoreflector and mounted it nearby. Panel 4 just happened really really fast [[Special:Contributions/108.162.217.137|108.162.217.137]] 18:28, 2 November 2014 (UTC)

Why does the fourth paragraph mention signaling the reflector? You don't have to tell a mirror that there's a laser incoming. He's just claiming to have intentionally aimed at a reflector when it looked like he missed his shot. --[[Special:Contributions/173.245.52.68|173.245.52.68]] 22:05, 2 November 2014 (UTC)

Yeah, I don't know why the second half of the fourth paragraph is there either as it seems irrelevent to the comic or the retroreflectors. [[User:Squirreltape|Squirreltape]] ([[User talk:Squirreltape|talk]]) 12:33, 3 November 2014 (UTC)

+1. Agreed. Don't get that part about 'signaling' at all. Should be elaborated-upon or removed. I added a note with the body of the descrption becauwse I'm a newbie to Wiki-editing.[[Special:Contributions/108.162.219.134|108.162.219.134]] 21:37, 3 November 2014 (UTC)

Talk:1441: Turnabout

2014-11-03T21:34:46Z

108.162.219.134:

1441: Turnabout

2014-11-03T21:31:52Z

108.162.219.134: /* Trivia */

{{comic
| number = 1441
| date = October 31, 2014
| title = Turnabout
| image = turnabout.png
| titletext = Whenever I miss a shot with a sci-fi weapon, I say 'Apollo retroreflector' really fast, just in case.
}}

==Explanation==
In the comic, two people are engaging in a battle with laser guns. One appears to gain the upper hand as he jumps on an obstacle, as the other's shot goes wide. He delivers the classic line [http://tvtropes.org/pmwiki/pmwiki.php/Main/AnyLastWords "Any last words?"] and is answered with the confusing phrase "Apollo retroreflectors". The earlier wild shot, reflected off the Moon, promptly lances down from space and hits him in the back.

A {{w|retroreflector}} is a device or surface that reflects light back towards its source. Several such devices {{w|List_of_retroreflectors_on_the_Moon|were placed on the Moon}} and have been used ever since by scientists on Earth to {{w|Lunar Laser Ranging experiment|measure the distance between the two bodies using laser ranging}}.

The title text may be a reference to the common practice of "calling bank" in the game of basketball. In basketball, the backboard may be used to deflect the ball into the hoop. This is called a "bank shot." In casual games, if the player using the backboard in this way does not indicate that it was intentional (usually by "calling bank" before releasing the ball), the basket may not be counted in order to not give the player credit for a wild shot that happened to go in. When a player releases a shot that they realize is off the mark they sometimes quickly say "bank" to try and fool the other players into thinking that they were intentionally trying to "bank" the ball off the backboard into the hoop. In the title text scenario, "Apollo retroreflector" is used the same way "bank" is in basketball, i.e., the shooter meant to hit the target by reflection rather than directly.

[[Randall]] discussed the effect of hitting the Moon with lasers in [http://what-if.xkcd.com/13/ What If: Laser Pointer] and the likelihood of hitting a celestial object with a laser in [http://what-if.xkcd.com/109/ What If: Into the Blue].

===Trivia===
Retroreflectors where placed by the American {{w|Apollo 11}}, {{w|Apollo 14|14}}, and {{w|Apollo 15|15}} missions. The Soviet {{w|Lunokhod 1}} and {{w|Lunokhod 2|2}} rovers also carried such reflectors; attempts to use them for laser ranging were unsuccessful from 1971 to 2010, but were successfully renewed after the rovers' positions were photographed by the {{w|Lunar Reconnaissance Orbiter}}.

The likelihood of the wild shot being aimed at the Moon is fairly low in itself, and the probability of accidentally hitting a retroreflector on the Moon is lower still. Even if it did, it is highly unlikely that a pistol-sized generator could produce a beam coherent enough to inflict damage after traveling to the Moon and back, as lasers built for the purpose of hitting retroreflectors on the Moon typically get a return around one quadrillionth of the original beam.

The title text mentions that you would need to say "Apollo retroreflector" really fast, because from Earth you would only have about [http://www.wolframalpha.com/input/?i=2+*+moon+distance+from+earth+%2F+speed+of+light 2.5 seconds] before the light is reflected back to its source; in reality, you would need to signal the retroflector before firing the laser, given that no information-carrier could catch up and pass the laser beam.

- This last phrase (starting at "in reality") needs further elaboration to be meaningful. Why does one need to signal the photoreflector for any purpose? Why would an information-carrier need to be sent/received? There is an unstated assumption here.

==Transcript==
[Two people engage in battle using handheld laser guns.]

[The first shot by each person misses. Person 2 is ducking behind a block.]

[Person 1 jumps on top of the block. Person 2 fires upward and misses again.]

[Person 2 falls over backward as Person 1 aims his laser pistol.]
Person 1: Any last words?
Person 2: "Apollo retroreflectors".
Person 1: What?

[A laser shot comes down from the sky and hits Person 1 in the back, knocking the pistol out of his hands.]

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Space]]