explain xkcd - User contributions [en]

Talk:3172: Fifteen Years

2025-11-25T03:42:28Z

Clayel:

Part of a series:
* https://xkcd.com/1141/
* https://xkcd.com/1928/
* https://xkcd.com/2386/
--[[User:Pgn674|Pgn674]] ([[User talk:Pgn674|talk]]) 21:28, 24 November 2025 (UTC)
:[[:Category:X Years]]. [[Special:Contributions/64.201.132.210|64.201.132.210]] 22:03, 24 November 2025 (UTC)
"Growing old is a fabulous alternative to death." [[Special:Contributions/85.255.235.101|85.255.235.101]] 21:30, 24 November 2025 (UTC)

OH MY GOD THIS IS SO SWEET EEEEEEEEEE. So happy for you Randall! <3 '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 21:36, 24 November 2025 (UTC)
: this made me, too, tear up - [[User:Vaedez|Vaedez]] ([[User talk:Vaedez|talk]]) 00:22, 25 November 2025 (UTC)

Growing old ... '''together'''. [[Special:Contributions/64.201.132.210|64.201.132.210]] 21:59, 24 November 2025 (UTC)

The paragraph about the title text could use a reference to the series of comics of the form "Students graduating this year have never...". I'm not sure how to find them. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 22:11, 24 November 2025 (UTC)
: I added a link to what I think is the right category. It might be a little too broad though. [[Special:Contributions/2601:281:C802:9170:0:0:0:4150|2601:281:C802:9170:0:0:0:4150]] 01:53, 25 November 2025 (UTC)

Just. The. Cutest. This is an ideal relationship.--[[User:Maxcodes|Maxcodes]] ([[User talk:Maxcodes|talk]]) 22:32, 24 November 2025 (UTC)

I love being reminded I’m (pretty dang sure I’m) going to die alone, yaaaaaay [[Special:Contributions/2600:4040:12A0:E200:D1D1:1F63:C1A:31F2|2600:4040:12A0:E200:D1D1:1F63:C1A:31F2]] 23:05, 24 November 2025 (UTC)

yay they have survived [[User:Mathmaster|Mathmaster]] ([[User talk:Mathmaster|talk]])

As John Lennon once said, “Grow old along with me.” [[User:KelOfTheStars!|KelOfTheStars!]] ([[User talk:KelOfTheStars!|talk]]) 00:19, 25 November 2025 (UTC)

This weekend, as well as today, I've been quite sick. This was a much-needed boost. <3 love ya, Randall. [[User:DollarStoreBa'al|--'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]]]] ([[User talk:DollarStoreBa'al|talk]]) 02:28, 25 November 2025 (UTC)

This might be my favorite xkcd comic of all time. [[Special:Contributions/68.2.204.250|68.2.204.250]] 03:02, 25 November 2025 (UTC)

Based on the pattern, the next in the series will be "Eighteen Years" [[Special:Contributions/209.52.88.184|209.52.88.184]] 03:23, 25 November 2025 (UTC)
::Nah, a +5,+3,+5,+3 seems too basic. Maybe 22 would work, since this is maximum k for which the grid graph P_2 X P_k is a subgraph of the n X n knight graph. Definitely didn't just copy from the oeis. ANYWAYS, by the time they get to 46 we'll have solved it by then... --[[Special:Contributions/2.50.0.22|2.50.0.22]] 03:39, 25 November 2025 (UTC)

Very happy for Randall here, this is very sweet. [[User:Clayel|Clayel]] ([[User talk:Clayel|talk]]) 03:42, 25 November 2025 (UTC)

3137: Cursed Number

2025-09-04T03:25:23Z

Clayel: add link to a memetic cognitohazard from scp

{{comic
| number = 3137
| date = September 3, 2025
| title = Cursed Number
| image = cursed_number_2x.png
| imagesize = 388x449px
| noexpand = true
| titletext = Another group of mathematicians is working to put an upper bound on the number, although everyone keeps begging them to stop.
}}

==Explanation==
{{incomplete|This page was created in a CURSED YEAR. Don't remove this notice too soon.}}
In the universe of this comic there exists some number that, through unknown means, is extremely harmful to the human mind to read it - an {{w|information hazard}}. Dangerous pieces of writing like this are a fairly common trope in speculative fiction, such as the {{w|Necronomicon}} in the {{w|Cthulhu Mythos}}, "[https://scp-wiki.wikidot.com/scp-033 memetic cognitohazards] in the {{w|SCP Foundation}}, and {{w|Monty Python}}'s {{w|Funniest Joke in the World}}.

Naturally, the mathematicians of this world are doing their best, in the interest of public safety, to keep this number away from as many human eyeballs as possible. Through some process they have figured out the number is at least 22 digits long; because numbers this large (greater than a 1022, or 10 sextillion) are extremely unlikely to be found in the day-to-day lives of non-mathematicians, the public officials have deemed it safe for people to go about their daily lives reading numbers again.

In the title text another group of mathematicians are trying to narrow down the number's identity even further. The more attributes of the cursed number the mathematicians identify, the easier it is for someone with morbid curiosity or someone researching more attributes of the number to discover the number themselves and get their mind damaged. This includes the researchers themselves, as they are now willingly going above the lower safe limit, increasing their chances of encountering it accidentally. Furthermore, the cursed number may appear as part of another number; for example, 223 appears as part of 2237. Worse, if the number could be determined in some controllable way that didn't necessarily expose its discoverers, it might be used as a weapon. This echoes concerns about knowledge gained from research on nuclear forces having been used to create atomic weapons.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[Blondie is standing at a lecturn with a sign that reads "math department", with Cueball on her left, and Hairbun on her right. To the left of them is a large screen.]
:Text on screen: [censored text with a skull] > 2.6 x 1021
:[Hairbun is holding up what appears to be the full paper report, the front showing illegible text surrounding what is visibly the same summary equation as appears on the screen.]

:[Caption below the comic:]
:Good news: Mathematicians have put a new lower bound on the '''cursed number that destroys the minds of all who perceive it'''!
:It's at least 22 digits, which means it's unlikely to be seen by any human no matter how many random numbers they look at.
:They say it's once again safe to view large random numbers without eye protection.

{{comic discussion}}<noinclude>
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Blondie]]
[[Category:Comics featuring Hairbun]]
[[Category:Math]]
[[Category:Comics with cursed items]]

3120: Geologic Periods

2025-07-26T00:36:33Z

Clayel: fix link

{{comic
| number = 3120
| date = July 25, 2025
| title = Geologic Periods
| image = geologic_periods_2x.png
| imagesize = 611x557px
| noexpand = true
| titletext = Geologists claim it's because the earlier Cenozoic used to be called the Tertiary, but that's just a ruse to hide the secret third geologic period, between the Neogene and the Quaternary, that they won't tell us about.
}}

==Explanation==
{{incomplete|This page was created by a Cretaceous raptor. Don't remove this notice too soon.}}

{| class="wikitable"
!Period
!Dates (millions of years ago)
!My Favorite Part
!My Biggest Complaint
!Explanation
|-
|Precambrian
|4500-539
|Life develops
|Snowball Earth episodes
|The {{w|Precambrian}} (italicized in the comic since it's not a {{w|Period (geology)|geologic period}}) is the first 88% of Earth's history, including the time 4.1 to 3.4 billion years ago when life on Earth began. The {{w|Snowball Earth}} hypothesis says that during some time spans in the past, Earth became nearly or entirely frozen, with no liquid water on the surface. It's related to the idea of the {{w|Greenhouse_and_icehouse_Earth#Icehouse_Earth|icehouse Earth}}, times when the planet fluctuates between glacial and interglacial periods (such as now).
|-
|{{w|Cambrian}}
|539-487
|Trilobites!
|Evolution could stand to calm down a little
|The {{w|Cambrian explosion}} was a sudden radiation of complex life forms when nearly all important animal phyla, or precursors to them, appeared.
|-
|{{w|Ordovician}}
|487-443
|Earth might have had rings
|Scary volcanic eruption in North America
|
|-
|{{w|Silurian}}
|443-420
|First land animals
|Earth's newfound mold problem
|
|-
|{{w|Devonian}}
|420-359
|Big mountains in Boston
|Yeah, sure, what those giant killer fish needed was armor
|
|-
|{{w|Carboniferous}}
|359-299
|Cool forests
|Bugs too big
|The {{w|Carboniferous#Terrestrial_invertebrates|'bugs' in this period}} included the largest-ever known land invertebrate, a {{w|Arthropleura|2.6-m (8.5-ft) millipede-like animal}}; the largest-ever known flying insect, resembling a {{w|Meganeura|dragonfly with a wingspan of ~75 cm (30 in)}}; and a {{w|Pulmonoscorpius|70 cm (2 ft 4 in) scorpion}}.
|-
|{{w|Permian}}
|299-252
|Pangea
|Google "The Great Dying"
|{{w|Pangaea}} was the most recent supercontinent containing nearly all of Earth's landmass. The Great Dying, more formally known as the {{w|Permian-Triassic extinction event}}, occurred at the end of the Permian and is the most severe of Earth's {{w|Extinction_event#The_"Big_Five"_mass_extinctions|'Big Five' mass extinction events}}. In it, 81% of marine species and 70% of terrestrial vertebrate species were wiped out.
|-
|{{w|Triassic}}
|252-201
|Tanystropheus
|Damage to Canada still visible from space at Manicouagan
|{{w|Tanystropheus}} was a verrrry long-necked dinosaur. {{w|Manicouagan Reservoir}} is a ring-shaped lake, the remains of the crater caused by a 5-km (3-mi) asteroid hitting {{w|Quebec}}.
|-
|{{w|Jurassic}}
|201-143
|Birds
|Parasitoid wasps
|
|-
|{{w|Cretaceous}}
|143-66
|Raptors
|Raptors
|
|-
|{{w|Paleogene}}
|66-23
|Pretty horseys!!!
|Paleocene-eocene thermal maximum
|The {{w|Paleocene–Eocene Thermal Maximum}} was a time where the global average temperature rose by around 5-8 °C is a relatively short period of time.
|-
|{{w|Neogene}}
|23-2.6
|Forests of Dracaena dragonblood trees
|Zanclean flood
|The {{w|Zanclean flood}} is theorized to be the flood that refilled the Mediterranean Sea.
|-
|{{w|Quaternary}}
|2.6-present
|Burrito invented
|Whoever picked the name for the third period of the Cenozoic
|
|}

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>
[[Category:Charts]]
[[Category:Geology]]
[[Category:Velociraptors]]
[[Category:Animals]]
[[Category:Food]]

3120: Geologic Periods

2025-07-26T00:36:17Z

Clayel: add paleogene and neogene explanations

{{comic
| number = 3120
| date = July 25, 2025
| title = Geologic Periods
| image = geologic_periods_2x.png
| imagesize = 611x557px
| noexpand = true
| titletext = Geologists claim it's because the earlier Cenozoic used to be called the Tertiary, but that's just a ruse to hide the secret third geologic period, between the Neogene and the Quaternary, that they won't tell us about.
}}

==Explanation==
{{incomplete|This page was created by a Cretaceous raptor. Don't remove this notice too soon.}}

{| class="wikitable"
!Period
!Dates (millions of years ago)
!My Favorite Part
!My Biggest Complaint
!Explanation
|-
|Precambrian
|4500-539
|Life develops
|Snowball Earth episodes
|The {{w|Precambrian}} (italicized in the comic since it's not a {{w|Period (geology)|geologic period}}) is the first 88% of Earth's history, including the time 4.1 to 3.4 billion years ago when life on Earth began. The {{w|Snowball Earth}} hypothesis says that during some time spans in the past, Earth became nearly or entirely frozen, with no liquid water on the surface. It's related to the idea of the {{w|Greenhouse_and_icehouse_Earth#Icehouse_Earth|icehouse Earth}}, times when the planet fluctuates between glacial and interglacial periods (such as now).
|-
|{{w|Cambrian}}
|539-487
|Trilobites!
|Evolution could stand to calm down a little
|The {{w|Cambrian explosion}} was a sudden radiation of complex life forms when nearly all important animal phyla, or precursors to them, appeared.
|-
|{{w|Ordovician}}
|487-443
|Earth might have had rings
|Scary volcanic eruption in North America
|
|-
|{{w|Silurian}}
|443-420
|First land animals
|Earth's newfound mold problem
|
|-
|{{w|Devonian}}
|420-359
|Big mountains in Boston
|Yeah, sure, what those giant killer fish needed was armor
|
|-
|{{w|Carboniferous}}
|359-299
|Cool forests
|Bugs too big
|The {{w|Carboniferous#Terrestrial_invertebrates|'bugs' in this period}} included the largest-ever known land invertebrate, a {{w|Arthropleura|2.6-m (8.5-ft) millipede-like animal}}; the largest-ever known flying insect, resembling a {{w|Meganeura|dragonfly with a wingspan of ~75 cm (30 in)}}; and a {{w|Pulmonoscorpius|70 cm (2 ft 4 in) scorpion}}.
|-
|{{w|Permian}}
|299-252
|Pangea
|Google "The Great Dying"
|{{w|Pangaea}} was the most recent supercontinent containing nearly all of Earth's landmass. The Great Dying, more formally known as the {{w|Permian-Triassic extinction event}}, occurred at the end of the Permian and is the most severe of Earth's {{w|Extinction_event#The_"Big_Five"_mass_extinctions|'Big Five' mass extinction events}}. In it, 81% of marine species and 70% of terrestrial vertebrate species were wiped out.
|-
|{{w|Triassic}}
|252-201
|Tanystropheus
|Damage to Canada still visible from space at Manicouagan
|{{w|Tanystropheus}} was a verrrry long-necked dinosaur. {{w|Manicouagan Reservoir}} is a ring-shaped lake, the remains of the crater caused by a 5-km (3-mi) asteroid hitting {{w|Quebec}}.
|-
|{{w|Jurassic}}
|201-143
|Birds
|Parasitoid wasps
|
|-
|{{w|Cretaceous}}
|143-66
|Raptors
|Raptors
|
|-
|{{w|Paleogene}}
|66-23
|Pretty horseys!!!
|Paleocene-eocene thermal maximum
|The {{w|Paleocene–Eocene Thermal Maximum}} was a time where the global average temperature rose by around 5-8 °C is a relatively short period of time.
|-
|{{w|Neogene}}
|23-2.6
|Forests of Dracaena dragonblood trees
|Zanclean flood
|The {{w|Zanclean flood}| is theorized to be the flood that refilled the Mediterranean Sea.
|-
|{{w|Quaternary}}
|2.6-present
|Burrito invented
|Whoever picked the name for the third period of the Cenozoic
|
|}

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>
[[Category:Charts]]
[[Category:Geology]]
[[Category:Velociraptors]]
[[Category:Animals]]
[[Category:Food]]

3079: Air Fact

2025-04-21T20:20:05Z

Clayel: add actual source of 8 spiders myth, which was made up intentionally

{{comic
| number = 3079
| date = April 21, 2025
| title = Air Fact
| image = air_fact_2x.png
| imagesize = 250x394px
| noexpand = true
| titletext = 'Wow, that must be why you swallow so many of them per year!' 'No, that's spiders. You swallow WAY more ants.'
}}

==Explanation==
{{incomplete|This page was created by a MICROSCOPIC ANT and contains only microscopic text. Don't remove this notice too soon.}}
Microbiologist [[Megan]] tells [[Cueball]] that every cubic meter of air contains thousands of microscopic ants. This, ironically, is a tall tale. Adult workers in some species of the genus {{w|Carebara|Carebara}}, the [https://www.guinnessworldrecords.com/world-records/341603-smallest-ant-species smallest known ants], can be 0.8 millimeters long, which is just below the 1.0 millimeter upper bound of "microscopic". It is therefore possible (barely) for an air sample to contain microscopic ants. However, given the subterranean, cryptic habitats typical of Carebara species, it is highly unlikely that these ants would appear in any, never mind every, air sample.

Initially incredulous, Cueball accepts Megan's fib as a fact, because he doesn't have any easy way to take samples of air and assess what these samples contain.

There are indeed microorganisms floating in the air, and getting air samples that will allow these microorganisms to be identified and quantified is indeed hard. [https://www.btpm.org/health-wellness/2018-05-23/allergy-season-is-back-but-how-do-we-know-whats-in-the-air Methods, with specialized collecting devices, exist] that take (one hopes) known volumes of air and deposit the particles contained in that air onto sticky surfaces which are then viewed under the microscope, or onto culture media which are then incubated. The methods are time-consuming and dependent on specialized knowledge (e.g., the identification of pollen grains or spores by surface features under the microscope), and are subject to numerous biases. For example, "sticky surface" methods will likely miss bacteria, and fail to identify 'nondescript' objects, whereas culture-based methods will not detect anything that will not grow on the selected media. The joke is that microbiologists are tempted to make up stories about what's in the air, because most people lack the data or skills to fact-check the stories.

In the comic, Megan presumably sampled a 10 cubic centimeter space of air and found 1 microbe (e.g. a bacterium, a mold spore, a protozoan cyst) in it. If she assumed that this was a representative sample, Megan could extrapolate from this datum to say that there are 10,000 microbes (which she then calls "ants") for every 1 cubic meter (1,000,000 cubic centimeters). Randall Monroe has made comics about dubious extrapolations, e.g. [[605]], but in this case, Megan's number is [https://pmc.ncbi.nlm.nih.gov/articles/PMC4515362/ within the range of microbial counts] that have been made in various indoor and outdoor environments.

The title text refers to the commonly believed myth that [https://www.bbc.com/news/uk-england-beds-bucks-herts-66319172 people swallow 8 spiders a year in their sleep]. Though oft quoted, [https://www.scientificamerican.com/article/fact-or-fiction-people-swallow-8-spiders-a-year-while-they-sleep1/ it has no basis in fact], and was actually [https://www.snopes.com/lisa-birgit-holst/ made up] to see if people would repeat the rumor without checking the original source. Bona fide ants, microscopic or otherwise, would be no more likely to enter a human's mouth than spiders, whereas Megan's "ants" (microbes) would wind up in the lungs, not the stomach, where (one hopes) the immune system would take care of them.

==Transcript==
:[Megan, with her palm out, is talking to Cueball.]
:Megan: Did you know that every cubic meter of air contains over 10,000 microscopic ants?
:Cueball: Wow, really?
:Cueball: I had no idea.

:[Caption below the panel:]
:The fact that taking air samples is hard presents microbiologists with a constant temptation.

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Biology]]
[[Category:Ants]]
[[Category:Spiders]]