explain xkcd - User contributions [en]

2423: Project Orion

2021-02-11T12:59:59Z

162.158.62.41: /* Explanation */

{{comic
| number = 2423
| date = February 11, 2021
| title = Project Orion
| image = project_orion.png
| titletext = If you tune out again, when you tune back in you'll be hearing about dusty plasma fission fragment rockets.
}}

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

White Hat and Cueball are having a conversation. In the first panel, Cueball is telling White Hat about his gardening experiences. White Hat tunes out for the middle two panels, and when he starts paying attention again, Cueball is discussing {{w|Project Orion (nuclear propulsion)|Project Orion}}.

Project Orion was an ambitious plan to launch enormous spaceships into orbit by detonating a series of nuclear bombs below them. The force from the explosions would be absorbed by a pusher plate on the bottom of the rocket, which is the detail Cueball is sharing when White Hat tunes back in. It was considered feasible for construction, but abandoned out of concerns for both cost and the idea of spaceships literally armed with atomic bombs. People probably daydream about this project because it seems like it could provide for rapid and massive entry into space, but was halted due to the intense danger. We likely have had sufficient technology for some time now to, with extensive additional engineering, somehow make this safe, but the space of risk is still so large and with such intense impact that such things are not allowed to happen.

The fact that physicists' conversations tend to converge towards Project Orion is similar to how biologists' conversations tend to converge towards carcinization in [[2418: Metacarcinization]]. This may turn out to be part of a series, similarly to the scaled world series, that will show similar examples in other fields, such as meteorologists' conversations converging toward tornadogenesis, mathematicians' conversations converging toward the Riemann hypothesis, or Randall's conversations converging toward raptors.

The alt text transitions to another cool nuclear rocket tech, [http://www.projectrho.com/public_html/rocket/enginelist2.php#fissionfragment dusty plasma fission fragment rockets].

Project Orion has been mentioned before, in [[786: Exoplanets]], where Beret Guy sums it up as "nuke-riding city ships."

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball is explaining to White Hat.]
:Cueball: Our garden grew really well last year, so we think we might put a second raised bed along the garage, if we can find a... [text fades to white]

:[White Hat stares into space for 2 frames.]

:Cueball: [text fades back in] ...thanks to X-ray [ablation?], the pusher plate would absorb the nuclear blast, recoil, and then return to position for the next bomb. Such a wild idea! Probably good that it was abandoned.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring White Hat]]
[[Category:Physics]]
[[Category:Convergence]]

2423: Project Orion

2021-02-11T12:59:29Z

162.158.62.41:

{{comic
| number = 2423
| date = February 11, 2021
| title = Project Orion
| image = project_orion.png
| titletext = If you tune out again, when you tune back in you'll be hearing about dusty plasma fission fragment rockets.
}}

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

White Hat and Cueball are having a conversation. In the first panel, Cueball is telling White Hat about his gardening experiences. White Hat tunes out for the middle two panels, and when he starts paying attention again, Cueball is discussing {{w|Project Orion (nuclear propulsion)|Project Orion}}.

Project Orion was an ambitious plan to launch enormous spaceships into orbit by detonating a series of nuclear bombs below them. The force from the explosions would be absorbed by a pusher plate on the bottom of the rocket, which is the detail Cueball is sharing when White Hat tunes back in. It was considered feasible for construction, but abandoned out of concerns for both cost and the idea of spaceships literally armed with atomic bombs. People probably daydream about this project because it seems like it could provide for rapid and massive entry into space, but was halted due to the intense danger. We likely have had sufficient technology for some time now to, with extensive additionally engineering, somehow make this safe, but the space of risk is still so large and with such intense impact that such things are not allowed to happen.

The fact that physicists' conversations tend to converge towards Project Orion is similar to how biologists' conversations tend to converge towards carcinization in [[2418: Metacarcinization]]. This may turn out to be part of a series, similarly to the scaled world series, that will show similar examples in other fields, such as meteorologists' conversations converging toward tornadogenesis, mathematicians' conversations converging toward the Riemann hypothesis, or Randall's conversations converging toward raptors.

The alt text transitions to another cool nuclear rocket tech, [http://www.projectrho.com/public_html/rocket/enginelist2.php#fissionfragment dusty plasma fission fragment rockets].

Project Orion has been mentioned before, in [[786: Exoplanets]], where Beret Guy sums it up as "nuke-riding city ships."

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball is explaining to White Hat.]
:Cueball: Our garden grew really well last year, so we think we might put a second raised bed along the garage, if we can find a... [text fades to white]

:[White Hat stares into space for 2 frames.]

:Cueball: [text fades back in] ...thanks to X-ray [ablation?], the pusher plate would absorb the nuclear blast, recoil, and then return to position for the next bomb. Such a wild idea! Probably good that it was abandoned.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring White Hat]]
[[Category:Physics]]
[[Category:Convergence]]

2357: Polls vs the Street

2021-02-09T15:09:14Z

162.158.62.41:

{{comic
| number = 2357
| date = September 9, 2020
| title = Polls vs the Street
| image = polls_vs_the_street.png
| titletext = Other pollsters complain about declining response rates, but our poll showed that 96% of respondents would be 'somewhat likely' or 'very likely' to agree to answer a series of questions for a survey.
}}

==Explanation==
This comic discusses getting data or opinions through a study (polls) or by getting them anecdotally (on the street). The phrase "voice on the street" is commonly used by news reporters who get opinions on issues by literally asking people walking by what they think, and has been previously mentioned (and derided) in [[756: Public Opinion]].

Many news organizations, and other data-driven institutions, conduct or commission polls to assess the opinions of the general public. These polls generally rely on asking a randomly selected and anonymous set of people a set of consistent, prepared and deliberately crafted questions about their opinions, experiences, and intents. The results of these polls are traditionally held to reflect the views of the public as a whole, within certain margins for error. Many news shows also conduct "man-on-the-street" interviews (more formally known as ''{{w|vox populi}}'', "voice of the people"), to provide a human face of "the public" and engage viewers more. Many pollsters, pundits, and politicians worry that polling data may not accurately reflect the true trends in public opinion, as in the infamous "{{w|Dewey Defeats Truman}}" newspaper headline, and so White Hat is here extolling the virtues of interviewing [https://www.logicallyfallacious.com/logicalfallacies/Appeal-to-Common-Folk "real people"] to get at that ground truth.

White Hat suggests that, while polls suggest "candidate X" is more favored, the people on the street that White Hat interviews are more supportive of "candidate Y". He implies that his experiences reflect reality better than the polls. There are a number of reasons why polls may not be entirely representative. The sampling method might not be genuinely random, some groups might be less likely than others to respond to a poll, and it's argued that some people express views that they consider to be more socially acceptable, even in anonymous polls, but vote differently in actual elections (examples include the "{{w|Bradley effect}}" and the "{{w|shy Tory factor}}"). Despite these concerns, there is little evidence that individual conversations do a better job at determining public opinion than polling.

This comic is very likely a reference to the {{w|2020 United States presidential election}}, which occurred on November 3, 2020 (about 2 months from the time of the comic's publication), which Democrat Joe Biden democratically won. Most polls showed Biden polling ahead of incumbent Donald Trump, but Trump and his supporters frequently argued that the polls are inaccurate, often arguing that they personally knew or talked to many Trump supporters, and few Biden supporters. At the same time, the fact that Trump won the 2016 election astonished many (including Randall) who had seldom met Trump supporters in their own lives and within their own social circles. This kind of anecdotal evidence is generally a poor basis for gauging public support, for multiple reasons. Politics in the US are frequently regional, so sampling in a single area is unlikely to be representative of the whole country, or even a whole state. It's not uncommon for gathering places (both physical and virtual) to attract people from one political group more than another, producing a skewed sample. If someone uses their own perception, rather than rigorous analysis, {{W|confirmation bias}} is likely to have a major impact (a person might pay more attention to supporters of their preferred candidate, and ignore political opponents).

This strip lampoons such thinking, as it quickly becomes clear that White Hat's methodology is heavily driven by selection bias. He's apparently talking only to the residents of his town, and extrapolating those results to the whole country. By that logic, he would conclude that ''everyone'' has visited his town, and most people live there. It is true that he's getting "ground truth", but it's also true that he's only sampling a very small (and highly idiosyncratic) part of the whole population.

The punchline in the final panel is a joke about the phrase "on the street". Usually this phrase means "anywhere out in public where the interviewer can openly approach people" (often a sidewalk near the studio), but White Hat is presumably taking the phrase literally and interviewing people he meets on the roadway. In the US, roads are generally reserved for vehicles (cars, trucks, motorcycles and in most areas bicycles), and walking or standing in the roadway for long periods is dangerous and usually illegal. White Hat's sample population thus consists only of the people who can be found on the roadway outside of designated pedestrian zones, who are generally from the small fraction of the population who have no qualms about the risks of being struck by moving vehicles or causing accidents when drivers swerve to avoid them.

The title text is a joke about {{w|selection bias}} and {{w|tautology}}. People who don't feel like taking surveys wouldn't get as far as answering a survey question about survey questions. However, it does touch on an issue raised by FiveThirtyEight after the election: that polls only measure people who are interested in answering polls, and [https://fivethirtyeight.com/features/could-social-alienation-among-some-trump-supporters-help-explain-why-polls-underestimated-trump-again/ that population may not be politically representative of the entire country].

==Transcript==
:White Hat: Polls are just numbers.
:White Hat: You have to talk to people on the ''street''.

:White Hat: Polls ''say'' most people support <Candidate X>.
:White Hat: But the people I talk to on the ''street'' support <Candidate Y>.

:White Hat: Polls ''claim'' most people don't live in my town and have never been here.
:White Hat: But the people I meet on the ''street'' tell a very different story.

:White Hat: According to ''polls'', most people don't like playing in traffic.
:White Hat: So why do I never seem to meet these people on the ''street''?

{{comic discussion}}

[[Category:Comics featuring White Hat]]
[[Category:Politics]]

Talk:2420: Appliances

2021-02-04T18:35:58Z

162.158.62.41:

This seems related to [[1890: What to Bring]]. [[User:Bubblegum|bubblegum]]-[[User_talk:Bubblegum|talk]]|[[Special:Contributions/Bubblegum|contribs]] 02:55, 4 February 2021 (UTC)

I actually disagree with the stove and washing dishes. In a large pot with water and with some stirring one can remove stains from cloths and kill germs. --[[Special:Contributions/141.101.96.28|141.101.96.28]] 07:08, 4 February 2021 (UTC)

It's interesting that all green squares are mirrored along the diagonal, with one exception, but no yellow ones at all. Usually you would assume that somewhat similar things result in a yellow square on both sides. [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 07:35, 4 February 2021 (UTC)

== A washing mashine can (and does) spin-dry clothes ==

A spin-drying program can usually be selected separately without getting the clothes wet. While this is not effective as a dryer, still much better than nothing.
----

I microwave can boil eggs, you just nweed to wrap them in foil and ensure they are covered by the boiling water. The foil acts as a faraday cage and ensures they only cook by conduction from the outside and the water stops arcing.
You cvan also make scrabled eggs and omlettes. [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]]) 09:31, 4 February 2021 (UTC)
:You seriously suggest putting foil into the microwave? I guess you don't mean tinfoil/aluminum? --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 09:58, 4 February 2021 (UTC)
:: You can put a foil there IF you know what you are doing. Try dissecting a microwave popcorn bag - its bottom has an aluminium foil inside and acts as a pan. I was surprised by inclusion of egg as okay by Randall though - I thought egg yolks were famous for infrequent but nasty [https://abcnews.go.com/Health/dangers-microwaving-eggs/story?id=51630977 superheating surprises] when microwaved. [[Special:Contributions/162.158.165.116|162.158.165.116]] 10:41, 4 February 2021 (UTC)

----
I didn't get this at all until I read the explanation, as I am red-green colorblind and the shades of red and green that Randall chose appear completely identical to me.
[[Special:Contributions/141.101.104.35|141.101.104.35]] 09:47, 4 February 2021 (UTC)

----

What a microwave does to bread is very weird. It seems to make the bread tougher (i.e., harder to bite through; in one case of a microwaved sandwich I was totally unable to bite off pieces), but doesn't make it stiffer (it ends up kind of like rubber). It doesn't wind up unevenly toasted like in the picture, but rather cooked in a completely different way. [[User:Magic9mushroom|Magic9mushroom]] ([[User talk:Magic9mushroom|talk]]) 11:22, 4 February 2021 (UTC)

----
Using a microwave to dry clothes is generally a bad idea, there is quite a high chance of burns. The most household appliance to quickly dry clothes beside a dryer is actually the freezer. [[User:Perigril|Perigril]] ([[User talk:Perigril|talk]]) 13:20, 4 February 2021 (UTC)

----
Updated transcript from [[1890: What to Bring]]. Considering the increased size of this table maybe something else is wiser? Does anyone know why the three first items are separate, or why the washing machine appears only to wet parts of the shirt? Should the cited text from the comic be written in all caps to match the comic? Should the "with a" between the pairs be replaced with something better to indicate that unlike What to Bring, Appliances does not have an equivalent to the "Should you bring _____ to ______"-text? --[[User:IonIceXIII|IonIceXIII]] ([[User talk:IonIceXIII|talk]]) 13:22, 4 February 2021 (UTC)

----
Attempting to do as well as possible in each square could make an interesting short video series. Stove/oven could probably achieve 6 greens, at least for quality of results if not for the time required [[User:Jgt|Jgt]] ([[User talk:Jgt|talk]]) 13:41, 4 February 2021 (UTC)

----
A classic example of a diagonally dominant matrix. [[Special:Contributions/162.158.62.41|162.158.62.41]] 18:35, 4 February 2021 (UTC)

2414: Solar System Compression Artifacts

2021-01-21T12:33:47Z

162.158.62.41:

{{comic
| number = 2414
| date = January 20, 2021
| title = Solar System Compression Artifacts
| image = solar_system_compression_artifacts.png
| titletext = Most of our universe consists of dark matter rendered completely undetectable by our spacetime codec's dynamaic [sic] range issues.
}}

==Explanation==
{{incomplete|Created by a MISSING PHYSICAL PHENOMENON LOST DUE TO HIGH COMPRESSION. More on the title text - Dark matter and dynamic range issues need to be explained in more detail. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

{{w|Voyager 1}} is a [[:Category:Space probes|space probe]] launched by the United States in 1977. Originally designed to study the outer planets of the {{w|Solar System}}, it is now several decades into an extended mission beyond Neptune.

When images are compressed by a {{w|lossy compression}} format (e.g. {{w|JPEG}}), visual artifacts are created. The Voyager probe has made history for passing many milestones of our solar system. Randall here is suggesting that the probe has passed the artifacts. This cannot be true, as the solar system does not have compression artifacts{{Citation needed}}. However, the slightly discolored regions often created by compression may be a metaphor for the region of space that that solar radiation prevents from being a complete vacuum. Voyager 1 has passed through numerous such boundaries, as mentioned previously in [[1189: Voyager 1]].

Compression artifacts are often caused by large changes in coloration over a short distance, and Randall could feel that the drastic change in coloration from bright sun to dark vacuum could be creating a compression artifact around the Sun, somewhat like the Sun looking blurry due to low video quality. However, there is no definite region where solar radiation stops, only a boundary where it fades to a level lower than that of radiation from other sources. Some compression methods result in compression artifacts that behave in the same way, fading as the distance from the color boundary increases but never completely disappearing.

The 'solar system' in the snapshot appears to be a 4-bit greyscale-plane at a more pixelated level than the image given. It can be picked out as being in 16 'banded' levels from the brightest (closest zones, within this image, to the Sun) to darkest (the furthest illustrated expanses, heading into interstellar space), with irregular or non-trivial transitional edges but no obvious or dominant dithering/speckling or 'noise'. The Voyager image (and track) is overlaid at finer resolution in the white 'line drawing' format.

The 'apparent pixels' seem to be at a resolution of close to the order of 1AU². A rough count of the pixelation boundaries from the craft to the leftmost edge, plus an additional allowance for the likely radius of the 'sun' (or, rather, its solar wind density, or similarly represented measure) still beyond the edge, is surprisingly close to to the 150 AU or so of distance that Voyager 1 is at, currently.

For perspective, the Earth is then ''by definition'' within/adjacent to the single lower-resolution 'pixel' that holds the Sun, and currently over on its far side. But the Sun itself is not even visible. It would be a dotted so far beyond the left boundary of the image that Neptune, at around 30 'pixels' distance, may only ''just'' be placable within the leftmost extreme of this view at its own rightmost point in its orbit. - The overlaid Voyager 'sketch' (in its more native resolution/bit-depth and antialiasing) stretches out over maybe a dozen such low-res pixels/AUs, which is equivalent to slightly more than the radius of Saturn's orbit or the entire diameter of Jupiter's!

In the title text the mystery of the undetectable {{w|Dark Matter}}, which is makes up most of the mass in the universe, is explained since this dark matter is rendered completely undetectable by our spacetime codec's {{w|dynamic range}} issues.

==Transcript==
:[Irregular bands of gray are shown, shading from a white circular segment on the bottom left side of the panel to completely black on the right. The bands have pixelated edges. A small white space probe is shown just outside the last dark gray band, in the completely black are. A dotted line starting from inside the dark gray ending at the space probe indicated that it is moving to the right out of the gray area. Close to the white area there are many bands packed closely together and with hard to define edges. But there are five gray areas clearly separated from the white, with a tendency to be elongated towards the space probes direction.]

:[Caption below the panel:]
:Milestone: '''''Voyager''''' has passed through the streaming video compression artifacts that mark the edge of the solar system

{{comic discussion}}

[[Category:Space probes]]

2413: Pulsar Analogy

2021-01-19T00:53:24Z

162.158.62.41:

{{comic
| number = 2413
| date = January 19, 2021
| title = Pulsar Analogy
| image = pulsar_analogy.png
| titletext = The #2 cause of astronomer hand injuries is trying to do vector math when the second axis points off to the right.
}}

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

{{w|Pulsar}}s are dead stellar cores that produce fast-spinning beams of radiation. Ponytail, an astronomer in this comic, explains a pulsar's fast rotation with an analogy about a tape measure retracting. This analogy could be seen as inaccurate, considering that the tape measure starts to rotate because the spring imparts a torque on the body of the tape measure. Pulsars rotate at their extreme speeds because of the conservation of momentum, which is similar to why a tape measure rotates if the tape and the body are considered together as a unit. As a star collapses into a pulsar, its natural rotation rate is greatly amplified by its shrinking moment of inertia.

That's probably totally wrong. But regardless, so is the idea of a laser measure being "exactly" like the emissions of a pulsar, which, although both pulse, are pulsing for totally different reasons, and are simply helping the mind hold the concept.

Retractable tape measures often have a belt clip on the side that doesn't have the label. The clip gives that side fewer points of contact on a flat surface than the flat label side would, and will spin longer because of less friction. Snapping the tape down will shorten the measure's lifespan, however: If the rivets that hold the bracket at the end of the tape shear off, the tape will tract entirely inside the measure body, and will be useless.

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

{{comic discussion}}

Talk:2413: Pulsar Analogy

2021-01-19T00:50:59Z

162.158.62.41:

I tried applying the right-hand-rule with the y-axis pointing to the right. :( I hurt my hand.
[[User:Avitzur|Avitzur]] ([[User talk:Avitzur|talk]]) 23:22, 18 January 2021 (UTC)
:Rotate your paper then do the right hand rule :)
:Hand joint exercises. Gentle motions with the wrist bent backwards, and bent forwards; 3-5 circles in both directions and both postures, twice a day. [[Special:Contributions/162.158.62.41|162.158.62.41]] 00:48, 19 January 2021 (UTC)
[[Special:Contributions/172.69.35.149|172.69.35.149]] 23:38, 18 January 2021 (UTC)

The analogy doesn't seem to be inaccurate in the way currently indicated. In both cases (tape measure and pulsar), conservation of ''angular'' momentum is what produces the result. With the tape measure, a small fast-spinning thing turns into a large slow-spinning thing; the opposite happens with a pulsar. [[Special:Contributions/172.69.35.150|172.69.35.150]] 00:05, 19 January 2021 (UTC)
:Isn't a tape measure bigger, not smaller, and slow-spinning, not fast-spinning, when it is elongated? This is very confusing. Thinking of how pulling the tape out stores energy. [[Special:Contributions/162.158.62.41|162.158.62.41]] 00:49, 19 January 2021 (UTC)

Talk:2413: Pulsar Analogy

2021-01-19T00:49:25Z

162.158.62.41:

I tried applying the right-hand-rule with the y-axis pointing to the right. :( I hurt my hand.
[[User:Avitzur|Avitzur]] ([[User talk:Avitzur|talk]]) 23:22, 18 January 2021 (UTC)
:Rotate your paper then do the right hand rule :)
:Hand joint exercises. Gentle motions with the wrist bent backwards, and bent forwards; 3-5 circles in both directions and both postures, twice a day. [[Special:Contributions/162.158.62.41|162.158.62.41]] 00:48, 19 January 2021 (UTC)
[[Special:Contributions/172.69.35.149|172.69.35.149]] 23:38, 18 January 2021 (UTC)

The analogy doesn't seem to be inaccurate in the way currently indicated. In both cases (tape measure and pulsar), conservation of ''angular'' momentum is what produces the result. With the tape measure, a small fast-spinning thing turns into a large slow-spinning thing; the opposite happens with a pulsar. [[Special:Contributions/172.69.35.150|172.69.35.150]] 00:05, 19 January 2021 (UTC)
:Isn't a tape measure bigger, not smaller, and slow-spinning, not fast-spinning, when it is elongated? [[Special:Contributions/162.158.62.41|162.158.62.41]] 00:49, 19 January 2021 (UTC)

Talk:2413: Pulsar Analogy

2021-01-19T00:48:04Z

162.158.62.41:

2413: Pulsar Analogy

2021-01-19T00:46:44Z

162.158.62.41: /* Explanation */

{{comic
| number = 2413
| date = January 19, 2021
| title = Pulsar Analogy
| image = pulsar_analogy.png
| titletext = The #2 cause of astronomer hand injuries is trying to do vector math when the second axis points off to the right.
}}

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

{{w|Pulsar}}s are dead stellar cores that produce fast-spinning beams of radiation. Ponytail, an astronomer in this comic, explains a pulsar's fast rotation with an analogy about a tape measure retracting. This analogy could be seen as inaccurate, considering that the tape measure starts to rotate because the spring imparts a torque on the body of the tape measure. Pulsars rotate at their extreme speeds because of the conservation of momentum, which is similar to why a tape measure rotates if the tape and the body are considered together as a unit. As a star collapses into a pulsar, its natural rotation rate is greatly amplified by its shrinking moment of inertia.

Retractable tape measures often have a belt clip on the side that doesn't have the label. The clip gives that side fewer points of contact on a flat surface than the flat label side would, and will spin longer because of less friction. Snapping the tape down will shorten the measure's lifespan, however: If the rivets that hold the bracket at the end of the tape shear off, the tape will tract entirely inside the measure body, and will be useless.

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

{{comic discussion}}