explain xkcd - User contributions [en]

3107: Weather Balloons

2025-06-27T01:59:51Z

Ace dm: /* Explanation */ typo

{{comic
| number = 3107
| date = June 25, 2025
| title = Weather Balloons
| image = weather_balloons_2x.png
| imagesize = 547x351px
| noexpand = true
| titletext = Once you add the balloons into the model, it makes forecasting easier overall--the forecast is always 'cold and dark, with minimal solar-driven convection.'
}}

==Explanation==
{{incomplete|This page was created by a METEOROLOGIST BOT WITH A FEAR OF PRE-COPULATORY SEXUAL CANNIBALISM. Don't remove this notice too soon.}}
A {{w|weather balloon}} is a balloon that carries meteorological instruments into the high atmosphere and sends readings back to scientists, who use the information to make weather and climate predictions. Typically it will rise up until the membrane breaks from too much pressure inside the balloon as outside in the top of the atmosphere. This is why the graph states that it is the number of balloons launches each day; because, if they were only launched on one day, they would all be gone from the sky the next day (the fragments of balloon falling back down).

The diagram in the comic claims that weather forecasting accuracy correlates with the number of weather balloons launched each day. But it forecasts that if the rate of balloon launches is sufficiently high, it could provide so many balloons that they actually impact the weather due to blocking out sunlight. So, if the balloons are not included into the weather model, the accuracy of the model based on the readings provided by the many balloons decreases. This starts to happen somewhere between 100 billion to 1 trillion weather balloons being launched each day. The accuracy of the model drops completely towards zero for around 10 trillion launched each day, where it even falls below the accuracy for just a single balloon (which may or may not be augmented by non-balloon information) at the start of the graph.

While there's correlation between number of weather balloon launches and weather model accuracy, they're not the only cause. Ground stations have been collecting and collating useful surface data for centuries. Scientific understanding of the physical processes in the atmosphere has also improved, only in part due to balloons, and the speed of computers used in analyses and simulations has increased by many orders of magnitude. The existence of weather and geophysical satellites also significantly improves forecasts, as they can continuously gain information about clouds and temperatures over huge areas, while weather balloons only capture information as they rise through a single air-column for a limited duration.

The surface area of the Earth is around 510 {{w|Trillion|(short-scale) trillion}} square metres, and a typical weather balloon (whilst smaller at launch) will expand to approximately 6 m diameter at altitude; this covers an area slightly under 30m², within a just marginally larger 'air surface area' at height. This makes it entirely possible for not far from 18 trillion standard weather balloons to potentially blanket the whole Earth; or even fewer, given the current availability of larger models each reaching more than twice the width, or four times the coverage of area. This isn't far off the implications given by the graph. On the other hand, because of the inherent translucency of the balloon material, the tendency to jostle vertically (the illustration implying that it's not just a single layer of close-packed balloons) and the need to synchronize launches and ascents to try to form any optimal single layer in one go might make it difficult to accomplish without a slightly greater magnitude of launches. (Or perhaps roughly doubling up the effect by only ever bothering to launch at local times that concentrate the coverage across the whole sunlit hemisphere at any given time.)

The joke in the title text is that when there are so many balloons that sunlight is entirely blocked, weather will always be the same: "cold and dark". So we won't need complex models to forecast it. Also when there is not heating of the Earths surface the solar driven convection that drives storms and weather patterns would stop. Of course humans and most life of Earth would die out. However, if it is humans who launches 20 trillions balloons each day, that will soon stop, and the weather would return to fairly normal once the balloons are gone in a days time after the last major launch. Of course the pollution from the trillions of balloons would last for longer, but not prevent the sun from reaching the Earths surface.

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

[A graph is shown. The X axis is labeled Number of Weather Balloon Launches Per Day. It's logarithmic, with ticks in powers of 10, and values shown at 1, 10, 100, 1,000, 1 million, 1 billion, and 1 trillion. The Y axis is labeled Weather Model Accuracy, no values are shown. The plot starts above the mark for 1 balloon, at about 40% of the maximum value of the curve, it quickly rises through a point labelled "Current Rate", at about 4000 launches per day and 85% of the maximum. The maximum value is reached at 100 million, plateaus until 10 billion, and then reduces even more rapidly down to perhaps 15% maximum accuracy above the 10 trillion mark.]

{{comic discussion}}<noinclude>

[[Category:Line graphs]]
[[Category:Comics featuring Cueball]]
[[Category:Weather]]

135: Substitute

2024-08-23T13:59:26Z

Ace dm: /* Explanation */ added missing word 'to'

{{comic
| number = 135
| date = July 31, 2006
| title = Substitute
| image = substitute.png
| titletext = YOU THINK THIS IS FUNNY?
}}

==Explanation==
This comic refers to the film ''{{w|Jurassic Park (film)|Jurassic Park}}'', a 1993 movie based on the 1990 novel by {{w|Michael Crichton}}. The film centers around a billionaire who bought an island and opened a zoo or theme park for dinosaurs that he has cloned from DNA recovered from blood found in fossilized mosquitoes. After a computer programmer shuts down the security systems to steal embryos for a rival company, several of the creatures, among which are the {{w|Velociraptor}}s subject of this comic, run loose and try to devour every human in the theme park.

Velociraptors (often shortened to "raptors") are a species of relatively small, carnivorous {{w|dinosaur}} that play a central role in the original film, as well as its sequels. In the film, packs of Velociraptors antagonize the main characters at various points, even entering buildings. According to newer researches, the Velociraptors in the film were erroneously based on the {{w|Utahraptor}} species of dinosaur. Unlike the movie, in which they are depicted as having a reptilian skin, both species of dinosaur in reality are theorized to have been feathered. The word "raptor" also refers to modern {{w|Bird of prey|birds of prey}}.

[[Randall Munroe|Randall]] is asked to substitute for [[Miss Lenhart]] in math class. The first page of the test he devises contains three questions, which have the recurring theme of humans running from said velociraptors. For the answers, see below. As Randall says in the comic: "This material is more vital than anything you've ever learned," the joke being that Randall is somehow fearful that such a thing could happen. Velociraptors, and in particular, the irrational fear of being attacked by them in the modern world, [[:Category:Velociraptors|appear several times]] in [[xkcd]]. This is the second such instance; the first is [[87: Velociraptors]].

Answers to the first two questions [http://fora.xkcd.com/viewtopic.php?f=7&t=120&start=40 used to be found] on the forum board, until it was shut down. The link is now defunct, but there's an [https://web.archive.org/web/20150326152959/http://fora.xkcd.com/viewtopic.php?f=7&t=120&start=40 archived version]:
*The first is 37.30194339616981 meters.
*The second is 57.19 degrees to either side of the wounded raptor, if the raptors at each instant move towards the current position of the person.
*The second is 59.83 degrees to either side of the wounded raptor, if the raptors' trajectories are optimal for catching the person as quickly as possible.

In the title text, Randall asks the kids whether they find this possibility humorous (and they rightfully should, considering that the chances of such a thing occurring are astronomically low).{{Citation Needed}}

==Transcript==
:[In a classroom, the board says "Math" on the top-left corner, and "Mr. Munroe" in the middle. A Cueball portrays Randall, standing in front of it, speaking to the class.]
:Randall: Miss Lenhart couldn't be here today, so she asked me to substitute.
:Randall: I've put out your tests. Please get started.

:[A student in the first row raises the exam paper and says:]
:Student: Mr. Munroe, Miss Lenhart never taught us this.

:Randall: That's because Miss Lenhart doesn't understand how important certain kinds of math are.
:Student: But this just looks--
:Randall: This material is more vital than anything you've ever learned
:Student: But--
:Randall: No buts.

:Randall: This is a matter of life and death.

:[Excerpt from the exam paper.]
:<tt>Name: _________</tt>

:[A stick figure is standing, hands over head. A velociraptor is running towards it.]

:<tt>1. The velociraptor spots you 40 meters away and attacks, accelerating at 4 m/s^2 to its top speed of 25 m/s. When it spots you, you begin to flee, quickly reaching your top speed of 6 m/s. How far can you get before you're caught and devoured?</tt>

:<tt>2. You're at the center of a 20m equilateral triangle with a raptor at each corner. The top raptor has a wounded leg and is limited to a top speed of 10 m/s.</tt>

:[A stick figure is shown in the above situation. The picture has a legend "<tt>(Not to scale).</tt>"]

:<tt>The raptors will run toward you. At what angle should you run to maximize the time you stay alive?</tt>

:<tt>3. Raptors can open doors, but they are slowed by them. Using the floor plan on the next page, plot a route through the building, assuming raptors take 5 minutes to open the first door and halve the time for each subsequent door. Remember, raptors run at 10 m/s and they do not know fear.</tt>

==Trivia==
This is the first xkcd comic featuring [[Miss Lenhart]].

{{comic discussion}}

[[Category:Comics featuring Miss Lenhart]]
[[Category:Comics featuring Randall Munroe]]
[[Category:Comics with color]]
[[Category:Velociraptors]]
[[Category:Jurassic Park]]
[[Category:Math]]
[[Category:Physics]]
[[Category:Comics featuring Cueball]]
[[Category:Kids]]

2952: Routine Maintenance

2024-06-29T15:54:05Z

Ace dm: /* Explanation */ changed nice to ice

{{comic
| number = 2952
| date = June 28, 2024
| title = Routine Maintenance
| image = routine_maintenance_2x.png
| imagesize = 299x413px
| noexpand = true
| titletext = The worst was the time they accidentally held the can upside down and froze all the Earth's magma chambers solid.
}}

==Explanation==
{{incomplete|Created by an ONCOMING LETHAL DUST CLOUD - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

A recommended routine maintenance step for many electronics, such as desktop computer towers, is to remove the buildup of dust on a regular basis. This bit of routine maintenance can help prevent the electrical components from overheating, and lengthen the lifetime of these electronics. There exists {{w|Gas duster|cans}} of high-pressure gas, as depicted, to blow dust out without a person blowing themselves, thus allowing them to keep their distance and not get a faceful of dust, or adding unintended moisture to the electronics.

This is suggesting that this is a maintenance step performed on the Earth itself, blowing gas into the Earth to force out the dust. However, filling the atmosphere with dust would be unhealthy and fatal to living beings, so as a safety measure everyone would have to take shelter. This is a reference to one theory about the extinction of many creatures, especially the (non-avian) dinosaurs, that a crashing meteor sent so much dust into the air that it killed off all non-avian dinosaurs in a much wider area than were directly affected by the initial impact. Those lineages that chanced to survive the global effects (including our own mammalian ancestors, and the avian dinosaurs that led to todays birds) must have been able to escape the worst of the disrupted ecosphere, perhaps some of them by already being more inclined/suited to living in burrows while the worst of the atmospheric effects subsided and let them exploit various newly vacant (and/or changed) environmental niches.

The image suggests that the "routine maintenance" for Earth would involve using the {{w|Hawaii hotspot}} (possibly <em>via</em> its most active volcano, {{w|Kilauea}}), as the point to insert the high-pressure gas, causing volcanoes to erupt in Iceland, the {{w|Aleutian Islands}} or the {{w|Kamchatka Peninsula}}, the {{w|Andes}}, and elsewhere; the two geographically-indeterminate plumes may represent Italy and Indonesia.

The title text mentions using the can upside-down, and this freezing solid the magma chambers. Pressurised canisters of air, as with similar aerosol sprayers, make use of a propellant gas that condenses into a liquid when compressed. As the can is sprayed, the release of pressure allows some of the liquid to evaporate and take the place of the released gases, become some of the gas subsequently released (or all of it, if there are no other contents required to fulfil its purpose as a spray). The propellant liquid/gas acts as a refrigerant, as its transition from dense liquid to space-filling gas requires it to 'boil off', this process needing to pick up {{w|Enthalpy of vaporization|heat (or 'enthalpy') energy}}. Under typical operation, this happens within the can itself, the heat being taken initially from the can itself as it tries to attain thermal equillibreum. As a result, the can itself (and the expelled gases) will be cooled a little as the heat 'loss' is taken from the general mass of the can, including its contents, and then (ultimately) anything touching or surrounding the slightly cooled can and its spray. This is precisely how a purposeful refrigerant acts, either as a one-time process or as a reversible cycle where repressuring a suitable gas can 'release' heat (the heat/enthalpy of condensation) at the 'hot side' of a rerigerator, leaving the system with more liquid it that it can later let boil and cool the 'cold side' of the system.

It is not normally useful for such a can to allow the liquid propellant-in-waiting to exit the container, as it would waste its usefulness as a source of pressure once it does. But by holding the container the wrong way up (which way that is being dependant upon its design, and intended use...) the pressurised contents push the liquid out via the nozzle's stream. The now exposed propellant is now free to evaporate into the air at atmospheric pressure, typically much lower than the constraints it had within the can, after landing directly upon whatever the can was sprayed at. The resulting demand for heat energy (much more rapid than normal, and likely concentrated upon a much smaller target than the can itself represents) produces a greater localised drop in temperature and can lead to freezing nearby liquids (which may or may not be intended/useful). Of course, the total 'cooling effect' of such a can does not change, depending upon how it is (mis)used, it merely changes the extent (and lifetime) of application, and how extreme the temperature change may be within a much more limited 'liberation' of its cooling ability.

Spraying canned "air" in reverse is a party trick used to very quickly cool beverages, being able to bring them down from room temperature to ice cold in seconds, if performed correctly. Some 'spray cans' are ''designed'' to let you freeze things (e.g. to help in plumbing repairs) or safely chill surfaces (e.g. for first-aid purposes), but these are exceptions (that require judicious use) and generally it is a wasteful use of a spray-can, if not actually unwise.

Given the location of the planetary-scale dust-busting 'air canister', it may be considered confusing which 'way up' is the correct orientation, given that Earth-gravity would be pulling the contents sideways (however that changes what the nozzle ends up ejecting from the can itself). But it would also have its own significant internal 'can-centric' gravity that possibly (depending upon how full of still-liquid propellant it is) exceeds that of the Moon, possibly letting all the denser liquid hold itself into the centre of the canister, even against the nearby Earth's gravity. Although, as significantly closer to the Earth, it could also be a far greater influence upon Earth's own tides (not alluded to in the comic), making the dusting of the atmosphere or the freezing of some of its magma secondary issues to the sheltering population.

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

:[The nozzle of a "Dust-Off" gas duster can is pointing into a hole on the Earth's surface in the Pacific Ocean around where Hawaii is located, and its trigger is pressed as an arrow indicates, resulting in dust clouds being released from five visible spots of the Earth. These eruptions can be seen in the Aleutian Islands or Kamchatka Peninsula, Iceland, the Andes, and two further in the eastern hemisphere on the other side of the Earth.]

:[Caption below the panel:]
:I know routine maintenance is important, but I hate how we all have to take shelter for 48 hours every year while they flush out the Earth's magma system for cleaning.

{{comic discussion}}

[[Category:Geology]]

2835: Factorial Numbers

2023-09-30T21:39:44Z

Ace dm: /* Explanation */

{{comic
| number = 2835
| date = September 29, 2023
| title = Factorial Numbers
| image = factorial_numbers_2x.png
| imagesize = 628x481px
| noexpand = true
| titletext = So what do we do when we get to base 10? Do we use A, B, C, etc? No: Numbers larger than about 3.6 million are simply illegal.
}}

==Explanation==
{{incomplete|Created by a VARIABLE-BASED BOT BEING ESCORTED OUT OF THE COMPUTER SCIENCE DEPARTMENT BY SECURITY - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic is based on the {{w|factorial number system}}, which is a way of writing integers or real numbers using {{w|factorial|factorials}} instead of powers. Unlike the 'proper' version of this system, [[Randall]]'s version does not include the rightmost digit that adds no information, since it is always 0.

A factorial is a product of positive integers. For instance, four factorial, written '4!', means 4×3×2×1 = 24. These can be used to write numbers in a strange way.

Normally, numbers are represented in a positional system with a constant base, especially base ten. This means that each digit in a number has a place value based on its position, and that value is a power of ten. For instance, the number 137 usually means 1×10² + 3×10¹ + 7×10⁰, i.e. one hundred, three tens, and seven units. We say that the 1 is in the hundreds place, the 3 in the tens place, and the 7 in the ones place (or units). The same number could be written in base sixteen as 89, meaning 8×16¹ + 9×16⁰, i.e. eight sixteens and nine units. The 8 is in the sixteens place, and the 9 is in the ones place.

In a "factorial base," instead of each place value being an escalating power of some constant base, each place value is an escalating factorial. The amount to multiply each place value by to get the next place value increases by 1 each time. So that same number (137 in base 10) could be written 10221, meaning 1×5! + 0×4! + 2×3! + 2×2! + 1×1!. We could say there is a 1 in the 120s place, a 0 in the 24s place, a 2 in the 6s place, another 2 in the 2s place, and a 1 in the ones place.

In normal base-n notation, n digits are used, running from 0 to n–1. For instance, in base ten, we use the ten digits {0,...,9}. In base sixteen, we need sixteen digits, so we use {0,...,9,A,...,F}. Any of these digits can be used in any position. But in factorial base, each position needs an increasing number of different digits to express all n-digit numbers. The comic labels each position with the equivalent base that would allow the same digits, e.g. the place value 3! is "base 4" because it uses the digits 0 to 3.

For instance, with just two digits, we can express some numbers with the digits 0, 1, and 2, like 21 = five. But we can't express 30 = six. As a result, Randall jokes that since we only have ten digits {0,...,9}, we can only express numbers with up to nine digits, making larger numbers "illegal." Randall believes that would make the largest "legal" factorial base number 987654321 = 9×9!+8×8!+7×7!+6×6!+5×5!+4×4!+3×3!+2×2!+1×1!, which in base ten is 3,628,799 (which he calls "about 3.6 million"). In fact, adding one to this number gives 1000000000, which still doesn't require any digits larger than 9, but he maybe wishes to stay away from the mere possibility of representing the digit that ''ought'' to use another symbol. The first number that actually cannot be represented with our usual ten symbols {0,...,9} comes right after 9987654321, which in decimal equals 36,287,999.

In the comic, the top example represents 3×720 + 5×120 + 3×24 + 0×6 + 1×2 + 1×1, after calculating each factorial accordingly, which gives the decimal value of 2835, [[2835|this comic's number]].

For completion of the examples shown in the panel, the numbers up to 200 in this variable base are:

1=1
2=10
3=11
4=20
5=21
6=100
7=101
8=110
9=111
10=120
11=121
12=200
13=201
14=210
15=211
16=220
17=221
18=300
19=301
20=310
21=311
22=320
23=321
24=1000
25=1001
26=1010
27=1011
28=1020
29=1021
30=1100
31=1101
32=1110
33=1111
34=1120
35=1121
36=1200
37=1201
38=1210
39=1211
40=1220
41=1221
42=1300
43=1301
44=1310
45=1311
46=1320
47=1321
48=2000
49=2001
50=2010
51=2011
52=2020
53=2021
54=2100
55=2101
56=2110
57=2111
58=2120
59=2121
60=2200
61=2201
62=2210
63=2211
64=2220
65=2221
66=2300
67=2301
68=2310
69=2311
70=2320
71=2321
72=3000
73=3001
74=3010
75=3011
76=3020
77=3021
78=3100
79=3101
80=3110
81=3111
82=3120
83=3121
84=3200
85=3201
86=3210
87=3211
88=3220
89=3221
90=3300
91=3301
92=3310
93=3311
94=3320
95=3321
96=4000
97=4001
98=4010
99=4011
100=4020
101=4021
102=4100
103=4101
104=4110
105=4111
106=4120
107=4121
108=4200
109=4201
110=4210
111=4211
112=4220
113=4221
114=4300
115=4301
116=4310
117=4311
118=4320
119=4321
120=10000
121=10001
122=10010
123=10011
124=10020
125=10021
126=10100
127=10101
128=10110
129=10111
130=10120
131=10121
132=10200
133=10201
134=10210
135=10211
136=10220
137=10221
138=10300
139=10301
140=10310
141=10311
142=10320
143=10321
144=11000
145=11001
146=11010
147=11011
148=11020
149=11021
150=11100
151=11101
152=11110
153=11111
154=11120
155=11121
156=11200
157=11201
158=11210
159=11211
160=11220
161=11221
162=11300
163=11301
164=11310
165=11311
166=11320
167=11321
168=12000
169=12001
170=12010
171=12011
172=12020
173=12021
174=12100
175=12101
176=12110
177=12111
178=12120
179=12121
180=12200
181=12201
182=12210
183=12211
184=12220
185=12221
186=12300
187=12301
188=12310
189=12311
190=12320
191=12321
192=13000
193=13001
194=13010
195=13011
196=13020
197=13021
198=13100
199=13101
200=13110

Note the apparent gap at 24 (4!) and 120 (5!) - apparent for those of us who are used to decimal numbers.

Factoradic™ numbers are actually less efficient than any other base. "Efficiency" for a base is normally defined by the radix economy. The actual definition is the size of the base (i.e. the number of possible digits) times the number of digits in a number, although it can be compared to {{w|binary-coded decimal|binary-coded decimals}}. Instead of using actual binary, a binary-coded decimal stores each decimal digit as a binary number. For example, 42 becomes (0100)(0010). This uses 8 bits, which is less efficient than the actual binary value of 101010, which is only 6 bits. It can vary which base is more efficient, like how from 9 to 15, quaternary is more efficient (base 4 * 2 digits = radix economy 8) than ternary (base 3 * 3 digits = radix economy 9). But as the number being represented goes up to infinity, the further you get from a hypothetical base e, the less efficient you become. As a quick example to demonstrate why large bases are less efficient, consider the number 3600. In base 60, it's only three digits, 1;0;0, but because each of those digits can have 60 possible values, its radix economy is 3*60=180. But even though the decimal representation uses a 4th digit, since there are only 10 possible values for each digit, the radix economy is only 4*10=40.

For a k-digit factoradic™ number, the 1st digit can have 2 values, the 2nd can have 3, the 3rd can have 4, up to the k-th digit having k+1 possible values, so the radix economy is effectively (k+1)(k+2)/2 - 1. Unfortunately, this is substantially more difficult to calculate, because it involved the inverse gamma function. But if you use ln n / ln ln n as an approximation of the asymptotic behavior of the inverse of Stirling's approximation, you can set up the limit ln n / ln^2 ln n, which diverges as n approaches infinity. Therefore, at least if you let factoradic™ numbers use other symbols for digits and increase past 10!, then no matter how large and inefficient of a base you're comparing it to, factoradic™ numbers will eventually be less efficient. Meanwhile, if you do stop at 10!-1, it's 9 digits, so its radix economy is 54. And if you solve 54 = b*floor(1+ln(10!-1)/ln(b)) for b, you find that b is approximately 6.75. So factoradic™ is more efficient than base 7 and up, but less efficient than binary, ternary, quaternary, quinary, and senary.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon. - Still needs a lot of deconstruction/reconstruction work on the [Poster:] to make it properly Transcripted (no tables, ideally!), but have improved the surrounding markup/descriptions}}
:[Cueball is standing in front of a large poster. There are two uniformed officers (a Ponytail and a further Cueball, wearing badged hats) approaching Cueball.]
:[Poster:]

:Variable-base Factoradic™ numbers
:{|
|Base 7||Base 6||Base 5||Base 4||Base 3||Base 2
|-
|3||5||3||0||1||1
|}

:Left side

:{| class="wikitable"
|Base 10||Factoradic
|-
|1||1
|-
|2||10
|-
|3||11
|-
|4||20
|-
|5||21
|-
|6||100
|-
|7||101
|-
|
|-
|21||311
|-
|22||320
|-
|23||321
|}

:Right side

:{| class="wikitable"
|Base 10||Factoradic
|-
|24||1,000
|-
|25||1,001
|-
|
|-
|5,038||654,320
|-
|5,039||654,321
|-
|5,040||1,000,000
|-
|
|-
|999,998||266,251,210
|-
|999,999||266,251,211
|-
|1,000,000||266,251,220
|-
|1,000,001||266,251,221
|}

:Cueball: Small numbers like seven or nineteen shouldn't use big numerals like "7" or "9".
:Cueball: I mean, "9" is the biggest numeral we have! It should be reserved for '''''big''''' numbers.
:Cueball: Small numbers should be written with small numerals like "1" or "2".
:Cueball: That's why my variable-base system uses...Hey! No, listen!
:[Caption under the comic:] Factorial numbers are the number system that sounds most like a prank by someone who's about to be escorted out of the math department by security.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Characters with hats]]
[[Category:Math]]
[[Category:Self-reference]] 
[[Category:Comics featuring Ponytail]] 
[[Category:Multiple Cueballs]]

2738: Omniknot

2023-02-15T19:29:46Z

Ace dm: Typo correction, changed it to is.

{{comic
| number = 2738
| date = February 15, 2023
| title = Omniknot
| image = omniknot_2x.png
| imagesize = 358x288px
| noexpand = true
| titletext = The Gordian knot is an omniknot tied using every bend in the Ashley Book of Knots, and then for extra security the upper rope at every crossing is connected to the lower with a randomly-chosen hitch.
}}

==Explanation==
{{incomplete|Created by THE KNOTTED OMNIBOT - Please change this comment when editing this page. Do KNOT delete this tag too soon.}}

Knots in the middle, from top to bottom:
* {{w|Granny knot}}: A bad knot, usually the result of an improperly tied reef knot.
* {{w|Reef knot}}: This one is properly tied, however, it shall never be used as a bend as it has a tendency to capsize and untie itself. A terrible, potentially dangerous choice.
* {{w|Sheet bend}}: Similar to the bowline, a popular, all around good choice, especially if one rope is thinner than the other (the loop shall be on the thinner rope).
* {{w|Double sheet bend}}: A more secure version of the previous knot, especially if one rope is much thinner than the other.
* {{w|Carrick bend}}: A very good bend, especially if both ropes are similar in kind and thickness. This version, however, with the ends emerging from the same side is weaker than if the ends were diagonal from each other.

On the sides are {{w|bowline|bowlines}} and each rope is terminated by a {{w|figure-eight knot}}.

The caption of the comic jokes that if you have several potential knots which could be tied in a given situation, rather than being forced to choose one, you can simply use all of them and create the comic's eponymous "Omniknot."

In the title text, the {{w|Gordian Knot}} is a knot which purportedly was extraordinarily complex and nearly impossible to untie. According to legend, when Alexander the Great was faced with the knot, he simply drew his sword and cut it in half, thereby "untying" it and solving the unsolvable. The Gordian Knot is now used as a linguistic metaphor to describe a problem whose solution, rather than being to directly solve it head-on, involves working around or otherwise bypassing its apparent constraints.

{{w|The Ashley Book of Knots}} is an encyclopedia describing thousands of different knots. Though it is now dated because it was written before the widespread adoption of synthetic fiber rope, it is still considered the reference in knot tying. Using all bends from the book and as many hitches would make the final result very complex indeed. Randall proposes here that this was the true origin of the mythical Gordian Knot.

In practice, it is not recommended to use overly complex knots as they provide little in term of additional security compared to a well chosen, simpler knot. The ease of tying and untying, especially in less than ideal conditions is also an important factor to consider. If strength is more important than the ease of tying and untying, splices should be considered instead of knots as they don't weaken the rope as much as knots.

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

:[There are two ropes tied together with several different kinds of knots.]

:[Caption below the panel:]
:If you know several knots and can't figure out which one to use, just tie one of each.

{{comic discussion}}

2533: Slope Hypothesis Testing

2021-10-26T05:22:36Z

Ace dm: Typo in p-value

{{comic
| number = 2533
| date = October 25, 2021
| title = Slope Hypothesis Testing
| image = slope_hypothesis_testing.png
| titletext = "What? I can't hear--" "What? I said, are you sure--" "CAN YOU PLEASE SPEAK--"
}}

==Explanation==
{{incomplete|Created by a SCREAMING STATISTICALLY SIGNIFICANT STATISTICS STUDENT. - Do NOT delete this tag too soon.}}
"Slope hypothesis testing" is a method of testing the significance of a hypothesis involving a scatter plot.

In this comic, Cueball and Megan are performing a study comparing student exam grades to the volume of their screams. Student A has the worst grade and softest scream, but Student B has the ''best'' grades and Student C the ''loudest'' scream. A trendline has been plotted, indicating a positive correlation between grades and volume...but the p-value is extremely high, indicating little statistical significance to the trend. P-value is based on both how well the data fits the trendline and how many data points have been taken; the more data points and the better they fit, the lower the p-value and more significant the data.

Megan complains about the insignificance of their results, so Cueball suggests having each student scream into the microphone a few more times. This technically increases the number of data points, and hence lowers the p-value; however, each student has exactly the same test scores (probably referencing the same datum as before) and have vocal volume ranges that don't drift far either (each seems to have a range of scream that is fairly consistent and far from overlapping), so the increase in data points is not as meaningful as the math implies. Megan is pleased by these results, but Cueball belatedly realizes this technique may not be scientifically valid.

The common p-value formulae assume the data points are statistically independent, that is, that the test score and volume measurement from one point don't reveal anything about those of the other points. By reusing the same exam scores across several data points each, Cueball and Megan violate the independence assumption and invalidate their significance calculation.

In the title text, several unidentified characters are trying to yell over each other, asking them to speak up so they can be heard, presumably over all the yelling.

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

2397: I Just Don't Trust Them

2020-12-12T19:10:42Z

Ace dm: /* Explanation */

{{comic
| number = 2397
| date = December 11, 2020
| title = I Just Don't Trust Them
| image = i_just_dont_trust_them.png
| titletext = I believe in getting immunity the old-fashioned way: By letting a bat virus take control of my lungs and turn my face into a disgusting plague fountain while my immune system desperately Googles 'how to make spike protein antibodies'.
}}

==Explanation==
{{incomplete|Created by a BAT. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
This comic is another comic in a [[:Category:COVID-19|series of comics]] related to the {{w|2019–20 coronavirus outbreak|2020 pandemic}} of the {{w|coronavirus}} {{w|SARS-CoV-2}}, which causes {{w|COVID-19}}.

Cueball partially echoes a statement made by anti-vaccine activists about "Big Pharma" (the powerful and profit-driven companies who develop pharmaceutical drugs such as vaccines). Anti-vaccine protesters falsely believe that vaccines contain harmful toxins that cause ill effects on the human body, and that the corporations that make them are not to be trusted because they are exploiting a captive public for profit while disregarding public health. The joke is that Cueball is revealed to be not talking about Big Pharma but, instead, bats.

According to the WHO, COVID-19 has an ecological origin in bat populations. Hence, Cueball sees the virus as something developed by bats, and the ambiguity by which he expresses his desire to not be infected adds to the joke.

The comic could simply be seen to serve as a compelling argument against the anti-vaccine movement, which is often criticized for spreading misinformation and increasing rates of disease, especially since the start of the COVID-19 pandemic. This comic comes shortly after the news of the development of several COVID-19 vaccines with high rates of success; there are concerns that herd immunity may be delayed if people refuse to take the vaccine.

The title text refers to getting immunity the old fashioned way, i.e. catching the disease and waiting for your immune system to build up a response. This is usually considered very healthy when immunity to local diseases is common, and can avoid the sudden forced evolution of new diseases among extensively hypercareful communities, but developing natural immunity is certainly incredibly dangerous during a new pandemic. One joke here is that many anti-vaxxers claim that it is more natural to not take a vaccine. Because many people conflate "natural" with "healthy", the assumption underlying the claim "it is more natural to not take a vaccine" is that it is therefore healthier.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball stands with his arms to his sides, facing Megan.]
:Cueball: I just don't trust them, and I don't want to put something they developed into my body.

:[Caption below the panel]:
:How I feel about bats

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Animals]]
[[Category:Biology]]
[[Category:COVID-19]]