explain xkcd - User contributions [en]

1893: Thread

2017-09-25T12:08:42Z

Seanthompson: /* Explanation */ popular is opinion, unless it can be backed with stats

{{comic
| number = 1893
| date = September 22, 2017
| title = Thread
| image = thread.png
| titletext = Since the current Twitter threadfall kicked off in early 2016, we can expect it to continue until the mid-2060s when the next Interval begins.
}}

==Explanation==
{{incomplete|Needs more. Do not delete this tag before the explanation is actually complete.}}

{{w|Characters in Dragonriders of Pern#F'nor|F'nor}} is a character from the popular{{Citation needed}} sci-fi/fantasy series ''{{w|Dragonriders of Pern}}'' by {{w|Anne McCaffrey}}. He is posting a {{w|Twitter}} comment (a "{{w|Conversation threading|thread}}" that's only one comment long, hence "1/1") about "{{w|Pern#Thread|Thread}}", a massively destructive alien organism from the same series. {{w|Pern}} is a fictional human-colonized planet and the main setting of the series.

Typically, when starting a series of tweets (used to post content longer than 140 characters), one will start the first tweet with "Thread: " and end it with 1/X. The second tweet will read 2/X, and so on. If X, the total number of tweets, is unknown at the start, it will be listed or 1/many or omitted: 1/

Here, there is a play on the Twitter thread and the actual threat to Pern.

The use of threads on Twitter became significantly more common in 2016 and through 2017. The title text dubs this "Threadfall." In the Pern novels, Threadfall is also the name for the beginning of 50-year cyclic periods when Thread attacks the world of Pern and its inhabitants, which occur between relatively safe "Intervals" of around 200 years. Since according to the title text Threadfall occurred in 2016, it should be expected to continue for ~50 more years until the mid-2060s, when the next Interval will begin.

==Transcript==

:[A mock-up of a “tweet” from the site twitter.com is shown. It contains a mock-up of a user photo of the fictional character F’nor that resembles [[Hairy]], including a tiny line sketch of F’nor’s brown dragon Canth flying overhead. Below the tweet are several action buttons typical of a Twitter post for comments, replying, likes, etc.]

:F’nor
:<span style="color:gray">@fnor</span>
:Thread: The greatest threat to our life on Pern 1/1

==Trivia==
On Friday, the header was replaced with a message from Randall about how he would be visiting the U.K. on the following week. It read as follows:
I'll be visiting the UK next week! You can join me in London from September 30-October 2 (at New Scientist Live, The Royal Institution, and Intelligence Squared), then from October 3-6 in York, Edinburgh, Cambridge and Ely, Oxford, and Cheltenham.

{{comic discussion}}

[[Category: Comics featuring Hairy]]

1887: Two Down, One to Go

2017-09-08T11:46:34Z

Seanthompson: it's not a coincidence. They're written that way.

{{comic
| number = 1887
| date = September 8, 2017
| title = Two Down, One to Go
| image = two_down_one_to_go.png
| titletext = The third row will probably have to wait until 2034, and maybe longer. If I see a daytime supernova, I'll replace the meteor storm with that and consider it 3/3.
}}

==Explanation==
In this comic, Randall lists three of the most spectacular astronomical sights: a total solar eclipse, the aurora borealis, and a meteor storm. In 2017, two of these phenomena happened within weeks of each other for observers in much of the US - a coincidence that Randall celebrates.

* Total solar eclipse: the total solar eclipse of August 21, 2017 was the first seen for decades in the continental United States. Randal already made [[:Category:Total Solar Eclipse 2017|several comics about this eclipse]].
* Aurora: Bar Alaska and perhaps parts of Maine, the aurora borealis is rarely visible from the continental USA. Randall bemoaned the fact he'd never seen one back in [[1302: Year in Review]] in 2013 - which also mentioned the 2017 eclipse. Randall likely finally saw it due to the [https://gizmodo.com/huge-solar-flare-disrupts-gps-satellites-1801838410 giant solar flares] in the week leading up to this comic.
* Meteor storm: A meteor storm is more than just a shower - while the best typical shower gives you a meteor or two per every minute, a storm gives you meteors every few ''seconds'' or better. The {{w|Great Meteor Storm of 1833}} produced hundreds of thousands of meteors per hour. In the alt text, Randall suggests the next one could be 2034, probably because this is predicted to be [http://adsabs.harvard.edu/full/2007JIMO...35....5M a good year for Leonids].
* Daytime supernova: A few stars, when they turn supernova, are so bright they can be seen during the day. {{w|SN 1054}} is one example. This is very rare and very hard to predict. [http://earthsky.org/brightest-stars/betelgeuse-will-explode-someday There is a (very small) chance that the giant star Betelgeuse] will go supernova within Randall's lifetime, allowing him to tick this off the list too.

[[Category:Total Solar Eclipse 2017]]

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

{{comic discussion}}

1867: Physics Confession

2017-07-25T12:34:47Z

Seanthompson: /* Explanation */

{{comic
| number = 1867
| date = July 24, 2017
| title = Physics Confession
| image = physics_confession.png
| titletext = "You know lightning, right? When electric charge builds up in a cloud and then discharges in a giant spark? Ask me why that happens." "Why does tha--" "No clue. We think it's related to the hair thing."
}}

==Explanation==
{{incomplete|This is my first contribution it should be looked over by someone before the tag is removed.}}

A {{w|Theory of Everything}} is a goal of modern physics which would describe the properties of all fundamental particles and all the interactions between them. The current approach to a theory of everything is to describe how at high energies different interactions, such as electromagnetic forces and the strong and weak nuclear interactions merge. It would be possible, in principle to demonstrate how the rest of known physics can be derived from that quantum behavior. This approach, however, leaves many everyday phenomena which are not understood by modern physics, and many {{w|Theory_of_everything#Arguments_against_a_theory_of_everything|arguments against a theory of everything}} suggest that it won't ever be able to actually precisely describe everything. This comic lists several of those phenomena:

The fine detail of how ice skates work is unknown. It is known that there is a film of water between the skate and the ice that lubricates sliding, but scientists dispute how the film gets there. The commonly held belief is that it is caused by the pressure of the narrow skate; another belief is that the ice is melted by the friction of movement; but both fail to fully explain why skating continues to be possible at temperatures that are significantly below 0 Celsius. A better explanation is simply that, near the melting point of a solid, there will be a thin layer of liquid on the surface due to the dynamic equilibrium between the two phases, hence why ice is slippery. This happens regardless of the presence of skates. A more complete explanation is given in the linked article: [http://lptms.u-psud.fr/membres/trizac/Ens/L3FIP/Ice.pdf Why is ice slippery?].

Physicists lack a clear understanding of the interactions involved in the flow of {{w|granular material}}s, such as sand. It is known that the behavior diverges greatly from that of a liquid, but it is unknown exactly how the flow works. [http://physicscentral.com/explore/action/granular.cfm PhysicsCentral:Granular Materials]

Modern physics also doesn't understand what makes electrons move from one material to another when two materials are rubbed against each other (the {{w|triboelectric effect}}), and why the transfer takes more electrons in one direction than in the other. However this happens, and it's the cause of {{w|static electricity}}, which can be seen when one rubs a latex rubber balloon against hair.

The title text mentions another common phenomenon that is poorly understood: the separation of charges in a cumulonimbus cloud. It is thought that interactions between ice and water transfer electrons, and then the different motion of ice (as hail) and water droplets in the cloud separates the charge. [http://www.srh.noaa.gov/jetstream/lightning/lightning.html NOAA How lightning is created].

==Transcript==
:[Megan is facing Ponytail and Cueball.]
:Megan: I'll be honest: We physicists talk a big game about the theory of everything, but the truth is, we don't really understand why ice skates work, how sand flows, or where the static charge comes from when you rub your hair with a balloon.

{{comic discussion}}
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Physics]]