explain xkcd - User contributions [en]

Talk:2935: Ocean Loop

2024-05-21T04:07:07Z

Val:

The 'standard' and '2x' sized images had unexpected sizes, so a Trivia section has been automatically generated, and an imagesize parameter has been added (at half size) to render the image consistently with other comics on this website. --[[User:TheusafBOT|TheusafBOT]] ([[User talk:TheusafBOT|talk]]) 20:47, 20 May 2024 (UTC)

Is there anyway to get notifications when a new comic comes out? I'm always late to these 21:27, 20 May 2024 (UTC)Jush
:I believe that there may be a Twitter (or X, or Xwitter, whatever we're calling it out) announcement direct from Randall's account, but I don't use that myself. And, like me, you were here ''right as it came out'', more or less, so so don't worry too much. You ''could'' write your own BOT-like poller (various ways, but do at least considerately throttle it back to checking perbaps no more frequently than every 15 minutes, 'cos too many people doing that would be 'problematical'), if you can't find a push-notifying service that does most of the hard work for you (and a whole host of other subscribers). [[Special:Contributions/172.70.85.241|172.70.85.241]] 22:23, 20 May 2024 (UTC)
:You can use the RSS feed: https://xkcd.com/rss.xml [[User:Val|Val]] ([[User talk:Val|talk]]) 04:07, 21 May 2024 (UTC)

Happy Victoria day to anyone else in Canada! [[Special:Contributions/162.158.146.235|162.158.146.235]] 21:39, 20 May 2024 (UTC)

Due to not being told about any Edit Conflict, I managed to co-edit the initial explanatuon with A.N.Other (sorry, haven't checked who, probably the first major editor in the page-history). I've put the most useful bit (IMO) of their article into mine, but some of it seemed wrong. Or at least not right.
*"because of the size and speed of a cruise ship, the ship likely wouldn't make it around the loop without falling off" - well, given the mass of water nicely holding itself to the loop, a ship floating around in it at the same speed would be holding itself to the loop quite nicely (moreso, perhaps, with its CoG taking a tighter loop than the fluid-loop).
**Of course, it could be slower, but that would mean fighting the current. Whatever huge velocity the water is going, you'd have to be capable of going full-reverse at ''significant'' speed to overcome that,
***Well, you could be ''just'' less than the ''just'' more than fast-enough water, but it's probably significantly faster than loop-speed, or a lot of edge-surface water would shed out of the topmost loop-trough due to fluidic friction against the trough itself.
***And there's the acceleration needed to match the fluid flow-rate, but that causes problems before 'falling off' is an issue. Imagine suddenly finding yourself going hundreds (thousands?) of knots sternwards in still water. Probably what it'd feel like, before even getting to the tilt (by which time, any ship that had survived is probably now close to water-speed).
*"Second even if they managed to make it through without falling, many of the passangers would abtain extreme injuries and/or likely fall off the ship all together (unlike {{w|rollercoasters}} the passengers aren't strapped down)" - If you experience negative Gs in a rollercoaster, it's not a true loop (just an awkward inversion). You should normally always stay at positive Gs, albeit at somewhere within 0<Gs<1 (which ''feels'' like negative, but is just short of weightlessness). Being strapped in is still important, but mostly for forces lateral to "local down" for where you are on the ride.
**...or, of course, if the ride malfunctions and leaves you stationary and inverted. Which happens, but that's not at all intended in most situations. There'd be no way an 'otherwise normal' flume-loop would do that, though refering back to the need of your ship to experience initial acceleration before it even hits the loop (and final deceleration once it exits it).
*"Third, because of the way the loop's designed, several hundreds (if not thousands) of tons of water is being launched onto the top of the cruise ship at a high speed. Needless to say, this would not only likely capsize the ship, but would also flatten any passenger on the deck." - The sudden undersea current is going to be a problem, but it's not going to be directed over the ship (save ''completely'' over the ship, in the loop far above).
**What you'll have is the turbulent local sea conditions. There'd be a 'standing wave-trough' in front of the point the jet of water is shown to emerge, itself probably a catastrophic problem for a ship, even an ocean-going one built in expectation of occasionally meeting {{w|rogue waves}}) and all the problems involved in traversing such rough seas. If your vessel can survive that (without spinning sideways and hitting the flume-trough, or breaking its back due to the extremely uneven and changing buoyancy along its length) then it's probably going to survive the much smaller amount of water that splashes 'over' its upper superstructure, compared to whatever relative mastrom of flow there will be passing under/against its (nominally) below-waterline hull.
I don't know how much 'reality' Randall has invested in this premise (I presume little, given the lack of pressure-trough in the 'still' water just short of the jet-emergence, nor any distortion in the sea surface wherever the jet originally sucked its water in from), but a lot of the issues of the looping-the-loop "What if" train will be the prime factors, plus maintaining general control (in river navigation, going downstream, between bridge piers, you really have to power your vessel forward, faster than the river itself, or risk losing yaw discipline on your craft). All the rest is icing on the cake of improbability. [[Special:Contributions/172.70.85.241|172.70.85.241]] 22:23, 20 May 2024 (UTC)
**It's a comic drawing after all, it's meant to illustrate the concept but leave the actual reality to our imagination. Conceptually it seems obvious to me that if the ship actually makes it through the loop, it exits fairly smoothly (class 2 or class 3 white water rafting).[[Special:Contributions/162.158.146.52|162.158.146.52]]

2545: Bayes' Theorem

2021-11-22T23:06:32Z

Val: Mention the header issue in the trivia

{{comic
| number = 2545
| date = November 22, 2021
| title = Bayes' Theorem
| image = bayes_theorem.png
| titletext = <nowiki>P((B|A)|(A|B)) represents the probability that you'll mix up the order of the terms when using Bayesian notation.</nowiki>
}}

==Explanation==
{{incomplete|Created by a FALSE POSITIVE - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

{{w|Bayes' theorem}} describes the probability of an event, based on prior knowledge of conditions that might be related to the event.

In this comic, the off-panel student knows that they are studying Bayes' theorem, so they use that prior knowledge to guess that the test result is a false positive. The punch line is the caption - if you know Bayes' theorem well enough, you don't need to actually calculate the probabilities.

The title text refers to the mathematical definition of Bayes' theorem: P(A | B) = P(B|A) * P(A) / P(B). P(A|B) represents the probability of some event A occurring, given that B has occurred. This is often referred to as "the probability of A given B". It can be hard to remember if P(A|B) means probability of A given B, or if it's B given A, and Randall's joke is based on this difficulty. Specifically, P((B|A)|(A|B)) would be the probability of (A|B) given (B|A), which makes it the probability that you got the order of the notation mixed up.

==Trivia==
When this comic came out, the title text was only "P((B" and the "Black Lives Matter" image in the header replaced by "(A", but this was quickly corrected.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Miss Lenhart using a pointer and pointing to a white-board with statistical formulae]
:Miss Lenhart: Given these prevalences, is it likely that the test result is a false positive?
:(off-panel voice): Well, this chapter is on Bayes' Theorem, so yes.

:[Caption below the panel]:
:Sometimes, if you understand Bayes' Theorem well enough, you don't need it.

{{comic discussion}}

[[Category:Comics featuring Miss Lenhart]]
[[Category:Statistics]]

2237: AI Hiring Algorithm

2019-12-04T19:14:56Z

Val: /* Explanation */

{{comic
| number = 2237
| date = December 4, 2019
| title = AI Hiring Algorithm
| image = ai_hiring_algorithm.png
| titletext = So glad Kate over in R&D pushed for using the AlgoMaxAnalyzer to look into this. Hiring her was a great decisio- waaaait.
}}

==Explanation==
{{incomplete|Created by an AI Algorithm. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

In this comic, [[Ponytail]] shows an analysis of a new artificial intelligence used to select who to hire among applications. The analysis shows that this AI mostly ignores common factors used for hiring new people. Instead, its main criteria for selecting new applicants is how much the new applicants are willing to contribute to the AI itself.

Although this does not imply sentience, it at least means the AI became {{w|Self-perpetuation|self-perpetuating}}, as it is selecting humans that will help make it more influential, giving it more power to select such humans, in a never-ending loop.

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

[slide shown on a wall screen]

DeepAIHire® candidate evaulation algorithm: inferred internal weightings

{|
!weight
!factor
|-
|0.0096
|Educational background
|-
|0.0520
|Past experience
|-
|0.0208
|Recommendations
|-
|0.0105
|Interview performance
|-
|783.5629
|Enthusiasm for developing and expanding the use of the DeepAIHire algorithm
|}

[[Ponytail]] points at the screen, saying: "An analysis of our new AI hiring algorithm has raised some concerns"

{{comic discussion}}
[[Category:Comics featuring Ponytail]]
[[Category:Artificial Intelligence]]

2237: AI Hiring Algorithm

2019-12-04T19:08:40Z

Val: /* Explanation */ Add a basic explanation.

{{comic
| number = 2237
| date = December 4, 2019
| title = AI Hiring Algorithm
| image = ai_hiring_algorithm.png
| titletext = So glad Kate over in R&D pushed for using the AlgoMaxAnalyzer to look into this. Hiring her was a great decisio- waaaait.
}}

==Explanation==
{{incomplete|Created by an AI Algorithm. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

In this comic, [[Ponytail]] shows an analysis of a new artificial intelligence used to select who to hire among applications. The analysis shows that this AI mostly ignores common factors used for hiring new people. Instead, its main criteria for selecting new applicants is how much the new applicants are willing to contribute to the AI itself.

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

[slide shown on a wall screen]

DeepAIHire® candidate evaulation algorithm: inferred internal weightings

{|
!weight
!factor
|-
|0.0096
|Educational background
|-
|0.0520
|Past experience
|-
|0.0208
|Recommendations
|-
|0.0105
|Interview performance
|-
|783.5629
|Enthusiasm for developing and expanding the use of the DeepAIHire algorithm
|}

[[Ponytail]] points at the screen, saying: "An analysis of our new AI hiring algorithm has raised some concerns"

{{comic discussion}}
[[Category:Comics featuring Ponytail]]
[[Category:Artificial Intelligence]]

2237: AI Hiring Algorithm

2019-12-04T19:04:58Z

Val: /* Transcript */ Fix table rendering

2237: AI Hiring Algorithm

2019-12-04T19:04:31Z

Val: /* Transcript */ Add transcript