explain xkcd - User contributions [en]

Talk:2982: Water Filtration

2024-09-11T20:01:51Z

Vkapadia:

On the activated carbon filter, that's a double entendre, referencing both activated charcoal filters often used in filtration systems and the nearby neutron source, which is radioactivity activating the carbon. [[Special:Contributions/172.71.254.23|172.71.254.23]] 04:32, 7 September 2024 (UTC)Corsac

There are a bunch of processes shown that are real, but not actually used in water filtration. For example, electrolysis is used to make hydrogen and oxygen gas, and reverse electrolysis is used in fuel cells to produce electricity, but the electricity cost of doing these steps to purify a useful amount of water would be prohibitive. [[Special:Contributions/162.158.159.14|162.158.159.14]] 06:18, 7 September 2024 (UTC)
:On the other hand, it would be a kind of "extra-intense distillation". We already basically have been "distilling water", as I see it, with the autoclave/condenser pairing that would certainly leave any remaining dissolved minerals or particulates behind. By splitting then recombining the component elements (and some basic gas-chromatography process, not shown) then you'd inarguably get water out that's about as pure as you can hope for in even the most {{w|The Waters of Mars|paranoid fantasies}} about the need for clean water.
:...of course, here it's not even the ''most'' energetic attempt to further 'refine' the components of "watery matter", with the assumed luxury of having energy (and indeed water) to burn... [[Special:Contributions/172.69.194.219|172.69.194.219]] 06:39, 7 September 2024 (UTC)
:Yes; I'm wondering if we should be a bit more specific than just "real" vs. "fake". Some of the processes would work, but wouldn't make the water purer; some are impractical but feasible; some aren't possible at all. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 16:10, 7 September 2024 (UTC)

Regarding condensers: Condensers are a real method of purifying water, although perhaps not commonly used to demineralize household well water. I frequently buy "purified" water that has been distilled which is simply boiling the water and then condensing the steam into pure water. This is great for use in tea pots or egg cookers or humidifiers to avoid mineral buildup inside the pots. [[User:Rtanenbaum|Rtanenbaum]] ([[User talk:Rtanenbaum|talk]]) 14:35, 7 September 2024 (UTC)

Regarding adding the well-water back in at the end: "Purified" water is often sold in the baby aisle for use in mixing baby formula, but the labels indicate that minerals have been readded to the water, which of course means it is no longer pure, and would not be useful if I want to avoid mineral buildup in a tea pot. [[User:Rtanenbaum|Rtanenbaum]] ([[User talk:Rtanenbaum|talk]]) 14:35, 7 September 2024 (UTC)

This comic made me realize how to fund space exploration: selling "artisinal space water" to gullib- I mean, discerning rich people. [[Special:Contributions/172.69.246.151|172.69.246.151]] 15:48, 7 September 2024 (UTC)

I have silt, iron, manganese, and microbes in my well.

In a real life, the first step will be mechanical filters: frog-screens, leaf nets, sand or paper media. In my well-water this takes most of the yuck out (as brown sludge).

Home-scale UV treatment is commonly sold (and apparently used; spares available) for spot-treating rural well water. Industrial UV exists for very expensive 'pure water' which must not make anybody sick. ALL water gets germs; UV may have less side-effect than Chlorine or Bromine.

Condensing (and distilling!) are standard household appliances for DIY distilled water. 'Activated' Carbon elements are VERY widely sold for taking taste/smell out of tap water.

"Water softening" (several types) is bog-standard technology out beyond the city mains. ([[User:PRR|PRR]] ([[User talk:PRR|talk]]) 19:08, 7 September 2024 (UTC) ...cntd below)
:Please sign your comments. And yes, it is. But not immediately before filtering by reverse osmosis. Reverse osmosis should remove almost all solutes, so the resulting pH should be very close to 0 and the concentration of no chemical except water should be significant. Water softening before or after is unnecessary. Don't get me wrong; RO is not perfect. But water softening is only ever necessary to remove large amounts of minerals that can leave scale, and that isn't an issue with high-purity water. [[User:EebstertheGreat|EebstertheGreat]] ([[User talk:EebstertheGreat|talk]]) 08:03, 8 September 2024 (UTC)
::NB, the comment ''was'' signed, if you check. This was fifth of sixth straight 'level zero indented' comments. Personally, if I'm not replying (sitting after any number of ":"s, per line) I prefer to add a <code><nowiki> </nowiki></code>-tag to force the linefeed (that isn't rendered, otherwise), rather than make it double-LF and potentially ''look'' like separate contributors.
::It also helps if it's written to look like it's the same contributor (disjointed paragraphs switch narratives seemingly at random don't help... ''especially''), but it isn't foolproof (and unsigned+signed contributions can look like one slightly rambling contributor, hence why signing does need to be added wherever necesary).
::But it's all in the eye of the beholder, some of whom may be the posters concerned and be absolutely sure that the future confusion won't exist. And sometimes (''very'' occasionally), there'll be a wish to interleave a comment specifically against an 'inner paragraph' of the wider message you're replying to. You can perhaps copy the 'official' signature of the original flow, like I did here. Can get messy any which way, of course.
::Some people might even think it better to (at least in non-reply additions, zero-coloned) just stick to one long rambling no-break paragraph. But I usually find that inelegent both in reading the Talk page and in its edit-source. Being terse and to the point perhaps helps, though, if possible. Not that I'm good at being laconic, as you can see! [[Special:Contributions/172.70.163.48|172.70.163.48]] 11:35, 8 September 2024 (UTC)

Of the radioactive treatments, Radon is not mentioned; surely this kills a few germs?
[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 19:08, 7 September 2024 (UTC)
:Using radon would be a bad idea. Even if one got all of the radon out afterwards (e.g. by {{w|sparging}}), it would leave behind radioactive daughter products, as well as the lead at the end of the decay sequences. Granted, {{w|Radithor|radium-enriched water}} was a commercial product, back in the day, but... still a bad idea. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 21:58, 7 September 2024 (UTC)
::Yeah, the philosophy tended to be "if it fluoresces, it impresses!", in the {{w|Radium fad|pseudoscientific quackery}} of the time... [[Special:Contributions/172.69.79.183|172.69.79.183]] 23:15, 7 September 2024 (UTC)
:Wait ... you have filters which turn frogs to brown sludge? Is that legal? -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 05:24, 8 September 2024 (UTC)
So much that I didn't notice in my first forty minutes looking at the comic while thinking "uhmm wut no! ! !" Y'all are why I come here especially when I think I thought I understood it and didn't need it explained. BTW? Are some for which the explain cannot be complete. The user interactive recent one with squirrels, fans, balls and things that made it kinda a pinball game but most assuredly not (mostly) come to mind. Thank you all. (Edited for clarity}[[Special:Contributions/172.70.43.54|172.70.43.54]] 04:19, 8 September 2024 (UTC)
[[Special:Contributions/172.70.39.34|172.70.39.34]] 04:28, 8 September 2024 (UTC)

Are we talking about water treatment, water filtration, or water purification? Because blending water and using UV are useful tools in water treatment but are not filtration and are pointless for purification. Treatment is anything done to make the water healthier or more pleasant to drink or better for equipment. Filtration requires physical separation of water from contaminants (which would not count most of these processes, and some, such as electrolysis, kinda break the definition water systems use since they separate at too fine a level to really count as a water filter anymore, despite the comic name). Purification is the elimination of anything that isn't water. I thought part of the joke was that it was supposed to be treatment for home faucets for drinking purposes. I wouldn't care except it would change the classifcation of the columns. [[Special:Contributions/172.70.178.122|172.70.178.122]] 10:49, 8 September 2024 (UTC)

Some references on how hypotonic water doesn't harm human beings:
https://www.medicinenet.com/is_drinking_distilled_water_good_or_bad_for_you/article.htm
https://www.medicalnewstoday.com/articles/317698#is-it-safe
[[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 12:58, 8 September 2024 (UTC)
:There's degrees of harm. Generally agreed that the danger isn't anywhere as bad as the 'scare stories'. (As per edit-comments, you don't explode from osmotic pressure by trying even a squirt of the ultrapure water sat around in school chemistry labs, but it probably saved having to resupply so much if incautious pupils didn't glug it down constantly.)
:For example, https://www.webmd.com/diet/distilled-water-overview certainly says that it's safe, but still does point out that...
::Distilled water lacks even electrolytes like potassium and other minerals your body needs. So you may miss out on a bit of these micronutrients if you drink only the distilled stuff.
::Some studies have found a link between drinking water low in calcium and magnesium and tiredness, muscle cramps, weakness, and heart disease. Also, distilled water may not help you stay hydrated as well as other kinds of water.
:...and this is reflected in many of the respectable "is it safe/dangerous?" articles. (The medicinenet link you give actually goes into more detail on these points. Don't know about medicalnewstoday, as I can't even easily get past its "privacy notice" 'cookiewall', the way it's configured.) Thus if we're discussing ''why'' we're adding this at all (and end up with "isotonic" being a buzzword, because it sounds better than "flavoured sugar water with some mineral salts"), I had tried to explain why it could be ''thought'' necessary to proportionately undo basically the prior (often unnecessary/improbable) purification process. Couched in terms (I imagined) would not promote the "your body asplode!" myth, either. [[Special:Contributions/172.70.91.90|172.70.91.90]] 13:33, 8 September 2024 (UTC)

::I don't feel like an edit war, but in fact ions are not lost, period. The gut actively transports ions ''in'', the osmotic pressure difference is nowhere near enough to remove ions that way. You don't get the ions in tap water, but they aren't actually nutritionally significant for essentially anyone.[[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 01:54, 9 September 2024 (UTC)

::: I don't think you're arguing about quite the same thing, if you want my opinion. But - unlike you lot - I'll not expand huge paragraphs on this issue. [[Special:Contributions/172.70.91.201|172.70.91.201]] 10:29, 9 September 2024 (UTC)

"It is unclear what happens to the neutrons present in the oxygen nuclei" They're used in the Neutron Source. [[User:Vkapadia|Vkapadia]] ([[User talk:Vkapadia|talk]]) 20:01, 11 September 2024 (UTC)

Talk:1512: Horoscopes

2015-04-15T21:10:15Z

Vkapadia:

So funny - especially the title text made me laugh :-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 07:05, 15 April 2015 (UTC)
:Nine months later, it would certainly eliminate the stress of wondering if you were gonna "get lucky" that night. - Equinox [[Special:Contributions/199.27.128.120|199.27.128.120]] 16:13, 15 April 2015 (UTC)

The "coriolis effect" in the title text refers to the spin direction of vortices (rotating currents such as cyclones, whirlpools, and water draining from a basin), which is counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere. The title text is a joke extending the reversal to the flow of time.
: The spin direction of whirlpools and basins is 'not' determined by the coriolis effect, on this scale its impact is way too small to make a difference. The title text refers to how the coriolis effect is often used to explain phenomena (especially with relation to the hemispheres), even when its wrong. --[[Special:Contributions/198.41.242.5|198.41.242.5]] 08:23, 15 April 2015 (UTC)

The events described during which the conception of a person with a given birth month occurred assumes that the parents were in the United States at that time. The seasons would be shifted by six months in the southern hemisphere, and the holidays of the 4th of July (Independence Day -- Aries), Halloween (Cancer, conception in October), Thanksgiving (Leo, conception in November), Mother's Day (Aquarius, conception in May), and the NCAA (college) basketball playoffs ("March Madness" -- Sagittarius) , might either not be celebrated or celebrated on a different day. [[User:The Dining Logician|The Dining Logician]] ([[User talk:The Dining Logician|talk]]) 08:11, 15 April 2015 (UTC)

"Today, horoscopes are admitted to be pseudoscience." Citation needed. But what rubbish. Horoscopes are not even pseudoscience, so who is it "admitting" they are? [[Special:Contributions/108.162.250.187|108.162.250.187]] 08:36, 15 April 2015 (UTC)

:Agree, I would like the citation for "today", as there were experiments disproving horoscopes in ancient Rome already (involving two babies born in same time, one rich, one slave). -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 12:48, 15 April 2015 (UTC)

The general trick to horoscopes is make them vague enough that anyone can think they're true, regardless of their sign. --[[User:PsyMar|PsyMar]] ([[User talk:PsyMar|talk]]) 10:34, 15 April 2015 (UTC)
:"You will have an opportunity today, meet someone new and should take care of your finances. Family matters will continue as per the last few days." [[Special:Contributions/141.101.98.192|141.101.98.192]] 13:41, 15 April 2015 (UTC)

I propose an addition to the "conceived during someone's wedding" -- it's more common that the conception is actually after the wedding, during the (somewhat expected) consummation by the actual married couple. Thus, "honeymoon babies"! --BigMal // [[Special:Contributions/108.162.221.181|108.162.221.181]] 12:53, 15 April 2015 (UTC)

Wait, I though Superman goes back in time not by "going against earths rotation, but simply by going faster than light?[[Special:Contributions/141.101.88.209|141.101.88.209]] 19:53, 15 April 2015 (UTC)

The expected conception column is off, therefore the explanations may be off. Length of a human pregnancy is 38 weeks after conception, or 9 1/2 months, not the 9 months that is commonly portrayed. I'm not sure if Randall took this into account or not. [[Special:Contributions/199.27.133.121|199.27.133.121]] 20:40, 15 April 2015 (UTC)
:This is true, except you must have meant 8½ month not 9½ since 38 weeks is less than 9 month. Actually it is very close to 8,75 month. But anyway you are correct, that all the dates should be fixed to go 38 weeks back, not 9 months!--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 20:54, 15 April 2015 (UTC)

No reference to the fact that November babies might be conceived on V day? [[User:Vkapadia|Vkapadia]] ([[User talk:Vkapadia|talk]]) 21:10, 15 April 2015 (UTC)

1204: Detail

2013-04-26T17:55:45Z

Vkapadia: /* Explanation */ Adding more to title text explanation.

{{comic
| number = 1204
| date = April 26, 2013
| title = Detail
| image = detail.png
| titletext = 2031: Google defends the swiveling roof-mounted scanning electron microscopes on its Street View cars, saying they 'don't reveal anything that couldn't be seen by any pedestrian scanning your house with an electron microscope.'
}}

==Explanation==
{{w|Google Earth}} is mapping software provided by Google that allows people to see the Earth from a birds-eye-view perspective. If you zoom in close enough, you can see individual streets – or in this case, a neighborhood.

{{w|Optical resolution|Resolution}} is a term (roughly) representing the scale of the smallest identifiable feature in an image. In the context of terrestrial image mapping, this would correspond to the width of the square occupied by a single pixel in a terrestrial satellite image. In this strip, Randall points out that the resolution of images available to Google Earth has been decreasing (improving) at an exponential rate for the past decade. This is due to the improving quality of satellite imaging technology, as well as integration of additional data sources, such as aerial photography and street-level roaming cameras. Each tick in the scale represents a resolution improvement by three orders of magnitude.

The {{w|Planck length}} is a unit of length and in principle the shortest measurable length, thus making it effectively the "resolution" of our reality. It is around 1.6×10-35 m, close to 10-20 times the diameter of a proton. The comic shows how the current growth trend in resolution of Google Earth will hit the Planck length around the year 2100, even though such result is currently considered impossible to achieve.

The title text refers to the fact that the trendline predicts an available resolution in the nanometer range by 2031, which would necessitate (using today's technology) the use of {{w|scanning electron microscope}}s to achieve. It also refers to some heat that Google received before about it's vehicle mounted cameras being an invasion of privacy. Google came back saying that nothing the cameras pick up can't be seen by a pedestrian walking by.

==Transcript==
:My Neghborhood's Resolution in:
:[A chart showing the Resolution of Google Earth increasing on a logarithmic scale towards the Planck Length, with resolution on the y-axis and time in years on the x-axis.]

{{comic discussion}}
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