Main Page

Explain xkcd: It's 'cause you're dumb.
(Difference between revisions)
Jump to: navigation, search
(Include List of unexplained comics in remaining calculation)
(17 intermediate revisions by 5 users not shown)
Line 1: Line 1:
 
__NOTOC__{{DISPLAYTITLE:explain xkcd}}
 
__NOTOC__{{DISPLAYTITLE:explain xkcd}}
 
<center>
 
<center>
<font size=5px>''Welcome to the '''explain [[xkcd]]''' wiki!''</font>
 
  
We have collaboratively explained [[:Category:Comics|'''{{#expr:{{PAGESINCAT:Comics|R}}-9}}''' xkcd comics]],
+
<font size=5px>''Welcome to the '''explain [[xkcd]]''' wiki!''</font><br>
<!-- Note: the -10 in the calculation above is to discount subcategories (there are 8 of them as of 2013-02-27),
+
We have an explanation for all [[:Category:Comics|'''{{#expr:{{PAGESINCAT:Comics|R}}-13}}''' xkcd comics]],
     as well as [[List of all comics]] and [[List of unexplained comics]], which is obviously not a comic page. -->
+
<!-- Note: the -13 in the calculation above is to discount subcategories (there are 8 of them as of 2013-02-27),
and only {{#expr:{{LATESTCOMIC}}-({{PAGESINCAT:Comics|R}}-10)}}
+
     as well as [[List of all comics]] and the pages it has been split across, which are obviously not comic pages.
({{#expr: ({{LATESTCOMIC}}-({{PAGESINCAT:Comics|R}}-10)) / {{LATESTCOMIC}} * 100 round 0}}%)
+
    The extra one difference corresponds to 404, which is not really a comic, even though we've categorised it so.
remain. '''[[Help:How to add a new comic explanation|Add yours]]''' while there's a chance!
+
-->
 +
and only {{PAGESINCAT:Incomplete articles|R}}
 +
({{#expr: {{PAGESINCAT:Incomplete articles|R}} / {{LATESTCOMIC}} * 100 round 0}}%) [[:Category:Incomplete articles|are incomplete]]. Help us finish them!
 
</center>
 
</center>
 
== Latest comic ==
 
== Latest comic ==
Line 24: Line 25:
 
<div style="float:right; margin: 0 0 1em 1em">{{Special:ContributionScores/10/7/nosort,notools}}<div style="font-size:0.85em; width:25em; font-style:italic">[[Special:ContributionScores|Lots of people]] contribute to make this wiki a success. Many of the recent contributors, listed above, have just joined. You can do it too! Create your account [[Special:UserLogin/signup|here]].</div></div>
 
<div style="float:right; margin: 0 0 1em 1em">{{Special:ContributionScores/10/7/nosort,notools}}<div style="font-size:0.85em; width:25em; font-style:italic">[[Special:ContributionScores|Lots of people]] contribute to make this wiki a success. Many of the recent contributors, listed above, have just joined. You can do it too! Create your account [[Special:UserLogin/signup|here]].</div></div>
  
You can read a brief introduction about this wiki at [[explain xkcd]]. Feel free to sign up for an account and contribute to the wiki! We need explanations for comics, characters, themes, memes and everything in between. If it is referenced in an [[xkcd]] web comic, it should be here.
+
You can read a brief introduction about this wiki at [[explain xkcd]]. Feel free to sign up for an account and contribute to the wiki! We need explanations for comics, characters, themes, memes and everything in between. If it is referenced in an [[xkcd]] web comic, it should be here.
  
* If you're new to wikis like this, take a look at these help pages describing [[mw:Help:Navigation|how to navigate]] the wiki, and [[mw:Help:Editing pages|how to edit]] pages.
+
*If you're new to wikis like this, take a look at these help pages describing [[mw:Help:Navigation|how to navigate]] the wiki, and [[mw:Help:Editing pages|how to edit]] pages.
  
* Discussion about various parts of the wiki is going on at [[Explain XKCD:Community portal]]. Share your 2¢!
+
*Discussion about various parts of the wiki is going on at [[Explain XKCD:Community portal]]. Share your 2¢!
  
* [[List of all comics]] contains a complete table of all xkcd comics so far and the corresponding explanations. The missing explanations are listed [[List of unexplained comics|here]]. Feel free to help out by creating them! '''[[Help:How to add a new comic explanation|Here's how]]'''.
+
*[[List of all comics]] contains a table of most recent xkcd comics and links to the rest, and the corresponding explanations. There are incomplete explanations listed [[:Category:Incomplete articles|here]]. Feel free to help out by expanding them!
 +
 
 +
*If you see that a new comic hasn't been explained yet, you can create it: '''[[Help:How to add a new comic explanation|Here's how]]'''.
 +
 
 +
*We sell advertising space to pay for our server costs. To learn more, go [[explain xkcd:Advertise Here|here]].
  
 
== Rules ==
 
== Rules ==
Line 37: Line 42:
 
If you want to talk about a specific comic, use its discussion page.
 
If you want to talk about a specific comic, use its discussion page.
  
Please only submit material directly related to —and helping everyone better understand— 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.
+
Please only submit material directly related to —and helping everyone better understand— 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 [[explain xkcd:Administrators|admin]], post a message to the [[explain xkcd:Community portal/Admin requests|Admin requests]] board.
 
If you need assistance from an [[explain xkcd:Administrators|admin]], post a message to the [[explain xkcd:Community portal/Admin requests|Admin requests]] board.
  
 
[[Category:Root category]]
 
[[Category:Root category]]

Revision as of 01:59, 30 October 2013

Welcome to the explain xkcd wiki!
We have an explanation for all 1 xkcd comics, and only 0 (0%) are incomplete. Help us finish them!

Latest comic

Go to this comic explanation

Gravitational Waves
"That last LinkedIn request set a new record for the most energetic physical event ever observed. Maybe we should respond." "Nah."
Title text: "That last LinkedIn request set a new record for the most energetic physical event ever observed. Maybe we should respond." "Nah."

Explanation

Ambox notice.png This explanation may be incomplete or incorrect: I've added some detailed explanation. Someone needs to proofread / review it. Might need some copy-editing.
Ambox notice.png This explanation may be incomplete or incorrect: Needs explanation of each of the messages

A gravitational wave detector is a device used to measure gravitational waves, small distortions of spacetime that were first predicted by Albert Einstein in 1916. Gravitational waves are ripples in the spacetime fabric itself.

The wikipedia article on gravitational waves describe them well. In simpler/layman's terms, imagine moving a stone through water while it is partly submerged. It'll cause waves on surface of water as it moves through it. These waves will spread away from the center of disturbance and as they move, they will cause the water molecules to oscilate around their mean positions. Similar waves are created in space-time fabric when two "heavy" celestial bodies interact with each other. If you concentrate on an area of water-surface (spacetime fabric) far away from the point of disturbance, you can observe that if the wave causes compression in one direction, it'll cause expansion of the fabric in other. See this page for nice animations (as well as gravitational waves wiki page).

Now consider spacetime fabric as a thin rubber sheet. If you mark any two points on this sheet and stretch/compress it along the axis joining those two points, the relative positions of these points with respect to their neighboring points do not change, but the distance between them changes. LIGO (Laser Interferometer Gravitational-Wave Observatory) is a large-scale physics experiment designed to detect this compression/expansion. Two facts need to be remembered to easily understand the experiment. First, speed of light (c) is a constant and velocity of an object is distance divided by time taken to travel that distance. Second, gravitational waves cause opposite effects (compression and expansion) in directions perpendicular to each other. Putting these two together, at LIGO, an experiment is setup, where two perpendicular long tunnels are constructed with apparatus to emit and detect laser beams. The apparatus is fitted with an extremely accurate clock to measure the difference between the time laser was emitted at one end and it's detection on the other. Multiplying speed of light and this measured time difference gives us the distance of the each tunnel. When the gravitational wave passes through earth, it is expected that the two tunnel lengths will differ due to the expansion/compression effect described above. This observation can be concluded as "detection of the gravitational wave passing through".

Megan, Cueball, and Ponytail are observing the results from a gravitational wave detector. From the patterns in the gravitational waves detected by this instrument, it might be possible to guess the nature of the event. e.g. Two bodies with dissimilar masses circling a fixed point, two bodies with circling each other, collision of two massive bodies, etc. It might also be possible to triangulate the location of event. Based on these two facts (location and nature of event) we might be able to determine which astronomical bodies caused this event (and well-being of those bodies afterwards). Thus, it provides an additional medium of observation of universe in addition to our telescopes. And this new medium might enable us to observe properties that we couldn't observe with our rest of the observation instruments.

However, in case of our heroes in this comic, they seem to be able to tell the events that have less to do with astronomical bodies and more with spam messages like invitations from Linkedin, a job networking site, a mortgage offer, and a social meetup. There is also a joke because the 'Local Group' is also the technical name for the group of galaxies containing the Milky Way. It is not clear if these so called "events" are causing gravitational waves to be generated or if someone (alien civilization?) is encoding spam messages in gravitational waves. The later would take an extremely advanced civilization, since it would require them to control orbits and oscillations of super-massive bodies (think at-least on the scale of the Sun, or typically several hundred times bigger than that). The second conclusion (someone is sending spam encoded in gravity waves) seems more plausible since the title text follows this up with a joke that the message senders have gone such a lengths that they caused the most energetic event recorded ever (maybe blew up few supernovae). One of the receivers is quite impressed with this and suggests that they have to reply to the spam just because the sender has made such an effort to send the message. The other person is not so impressed.

Various Events Mentioned

Trivia

This comic was published on a Thursday, not following the normal publish schedule, to coincide with the discovery of a clear gravitational wave signal on February 11, 2016. Gravitational waves were detected through the collision of 2 black holes.

Transcript

[Cueball, Megan, and Ponytail are in a room in front of a computer machine]
Megan: The gravitational wave detector works! For the first time, we can listen in on the signals carried by ripples in the fabric of space itself!
Computer: EVENT: Black hole merger in Carina (30 M, 30 M)
Computer: EVENT: Zorlax the Mighty would like to connect on Linkedin
Computer: EVENT: Black hole merger in Orion (20 M, 50 M)
Computer: EVENT: Mortgage offer from Triangulum Galaxy
Computer: EVENT: Zorlax the Mighty would like to connect on Linkedin
Computer: EVENT: Meet lonely singles in the local group tonight!


Is this out of date? Clicking here will fix that.

New here?

Last 7 days (Top 10)

Lots of people contribute to make this wiki a success. Many of the recent contributors, listed above, have just joined. You can do it too! Create your account here.

You can read a brief introduction about this wiki at explain xkcd. Feel free to sign up for an account and contribute to the wiki! We need explanations for comics, characters, themes, memes and everything in between. If it is referenced in an xkcd web comic, it should be here.

  • List of all comics contains a table of most recent xkcd comics and links to the rest, and the corresponding explanations. There are incomplete explanations listed here. Feel free to help out by expanding them!
  • If you see that a new comic hasn't been explained yet, you can create it: Here's how.
  • We sell advertising space to pay for our server costs. To learn more, go here.

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 —and helping everyone better understand— 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 admin, post a message to the Admin requests board.

Personal tools
Namespaces

Variants
Actions
Navigation
Tools

It seems you are using noscript, which is stopping our project wonderful ads from working. Explain xkcd uses ads to pay for bandwidth, and we manually approve all our advertisers, and our ads are restricted to unobtrusive images and slow animated GIFs. If you found this site helpful, please consider whitelisting us.

Want to advertise with us, or donate to us with Paypal?