Main Page
Welcome to the explain xkcd wiki!
We have an explanation for all 3315 xkcd comics, the 21 extra comics, and everything xkcd-related.Only 56 explanations (1.7%) are incomplete. Help us finish them!
New to editing? Start with This Week's Explanation for Improvement!
And seriously, my heartfelt thanks to you and everyone there. It's such a privilege to make something that people think is worth so much effort to explain <3
Latest comic
| Forms of Water |
Title text: The 'light' refers to bremsstrahlung. |
Explanation
This comic plays on the idea that the heavy water suggests the existence of "light water" via nucleon reduction. Since heavy water (or possibly, in this illustration, only semiheavy water) has hydrogen atoms that contains two nucleons and regular water has a hydrogen atom that contains one nucleon, an extrapolation could be made to conclude that a new water variant exists called light water, which has one or both "hydrogen" atoms that don't contain any nucleons at all. A hydrogen isotope of two nucleons is deuterium, while a hydrogen isotope of one nucleon is called protium. A "hydrogen" atom of zero nucleons would be identical to an ium, a fictional isotope as shown in 2719: Hydrogen Isotopes. There also technically exists positronium, an 'atom' with a positron assuming a role equivalent to a hydrogen's proton, although this is not an option indicated by the comic.
"Light water", as depicted in this comic, is fictional, as a hydrogen isotope of zero nucleons cannot exist. This is due to the fact that an atom's element type is dependent on the number of protons; a hydrogen atom is an atom containing one proton, and all atoms, by definition, have to contain at least one proton. It's possible for a positively charged antimuon to capture an electron, forming an "atom" called muonium which behaves chemically somewhat like hydrogen, with the differences caused by the antimuon's mass being only about one-ninth of a proton's. The antimuon has a half-life of about 2.2 × 10−6 s — long enough to measure some of the properties of "light water" made with it, but not long enough to collect or to do much in the way of chemistry.
A hydrogen atom has an associated electron, balancing the positive charge on its proton. The "light water" depicts the electron present, meaning the "light water" molecule would just be an anion, specifically a hydroxide ion (if there's still one atom of regular hydrogen), or an oxide ion (if both hydrogen atoms are "light").
The title text clarifies that "light" refers to bremsstrahlung. Bremsstrahlung is a type of electromagnetic radiation generated when a high-energy charged particle (usually an electron) passes close to the nucleus of an atom where it is deflected or slowed through Coulomb interactions, losing energy in the form of photons. This is therefore a wordplay on "light" (not heavy) and light (photons), as well as referencing the presence of the electron in "light water".
Although not depicted in the comic, deuterium-depleted water is sometimes known as light water. The term light-water reactor also shares a similar name. Tritiated water is another isotopic form of water not depicted in the comic, which could be considered 'heavier water'.
Transcript
- [Three diagrams of molecules are shown, each with an associated diagram. Each molecule features a large circle labeled O, representing an oxygen atom, with one smaller circle on each side labeled H, representing hydrogen atoms. Each molecule has an arrow pointing to the right-hand hydrogen atom, with the arrow starting near a diagram. Each diagram has a label below it.]
- [Diagram of an atom, with one black dot representing an electron in orbit around a nucleus consisting of one white circle representing a proton and one gray circle representing a neutron.]
- Heavy water
- [A similar diagram, with one black dot representing an electron in orbit around a nucleus consisting of one white circle representing a proton.]
- Water
- [A similar diagram, with one black dot representing an electron in orbit with no nucleus.]
- Light water
This Week's Explanation for Improvement
As part of the Explanation Improvement Project, each week the community selects one older, stagnant, or otherwise neglected explanation to expand and polish together. This week's pick is comic 1334: Second, you can help us by editing its explanation!
To get involved with the project, you can also nominate an explanation that you think should be improved, or vote on current nominations!
| Second |
![]() Title text: Let me just scroll down and check behind that rock. Annnnd... nope, page copyright year starts with '19'. Oh God, is this a WEBRING? |
Explanation
|
Welcome to This Week's Explanation for Improvement! Anyone is encouraged to help explain comic 1334: Second; click here to get started! If you are new to wiki editing, you can read our editing FAQ for guidance. Here are some suggestions for improving this explanation: |
Google is a popular search engine,[citation needed] and its searching algorithms are widely regarded as the most accurate and useful. If your search terms were sufficiently detailed, you will be able to find what you were looking for on the first page. Having to view the second page indicates your search terms were too vague or the answer to your query doesn't exist. When the search results typically number in the tens of millions (or more; in fact, more popular search results are in the billions), only the very first results are mapping to the real idea of the user, so the second page is typically is not helpful for the issue.
Cueball, after failing to find his query in the first page of results, takes a curious peek at the second page. This is represented by a not-at-all subtle metaphor in which Cueball is about to wander into a sun-baked desert. According to the title text, he finds one vaguely relevant webpage, but the copyright starting with '19', i.e from the 1990s or older, means that it's likely too old to be of any use.
The title text refers to webrings. Webrings consist of multiple websites that are connected together through links, usually with a common theme. They connect from one website to the next, eventually leading back to the starting site. They were popular in the 1990s as a form of web directory, popularized by the titular "The Webring" (later WebRing) and typically curated by a "ringmaster". Web directories in general fell out of use with the rise of search engines, so seeing a webring could mean a site has not been updated since then. Yahoo acquired WebRing in 1999 as part of its acquisition of GeoCities and rebranded the service to Yahoo! WebRing in 2000, leaving ringmasters "angry" in part because their customizable homepages had been replaced by the design of Yahoo! WebRing. Taking off in the early 2020s, people have been creating new webrings often in connection to the web hosting service Neocities, launched in 2013 and inspired by GeoCities.
Transcript
- [Cueball in a desert standing before a rock.]
- Rock: Greetings, stranger.
- Rock: Whatever quest drives you, abandon it.
- Rock: You shall find no answers in these desolate wastes.
- Cueball: I knew I wouldn't.
- Cueball: I guess I... just had to see.
- I hate feeling desperate enough to visit the second page of Google results.
New here?
You can read a brief introduction about this wiki at explain xkcd. Feel free to create an account and contribute to the wiki! We need explanations for xkcd comics, characters, what if? articles, and everything in between. If it is referenced in an xkcd comic, it should be here.
- See our editing FAQ for specific guidance to this wiki, and the more general help on how to edit wiki pages. There's also a handy wikicode cheatsheet.
- Discussion about the wiki itself happens at the Community portal.
- You can browse the comics from the list of all comics or by navigating the category tree at Category:Comics.
- The incomplete explanations are listed here. Feel free to help out by expanding them!
Rules
Don't be a jerk!
There are a lot of comics that don't have set-in-stone explanations; feel free to put multiple interpretations in the wiki page for each comic.
If you want to talk about a specific comic, use its discussion page.
Please only submit material directly related to xkcd and, of course, only submit material that can legally be posted and freely edited. Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users who repeatedly post such content will be blocked.
If you need assistance from an administrator, post a message to the Admin requests community portal.

