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August 15

Hydrogen Peroxide Poisoning

I am reaching out in the pursuit of obtaining additional information regarding hydrogen peroxide poisoning. I recall that this information was previously available on the Wikipedia website; however, I am currently unable to locate it.

There was a mention of using bicarbonate for maintaining a buffer, as well as the utilization of calcium as a buffering agent as long as the body would allow it. I'm interested in obtaining the references or sources for those specific comments. Furthermore, there was a reference to a potential remedy that was discussed, and I'm eager to gather more comprehensive information about it. 174.48.109.129 (talk) 19:04, 15 August 2023 (UTC)

I do not see any indication or suggestion in the literature that a buffer or any other substance might be helpful in the management of the effects of hydrogen peroxide ingestion, other than that victims who are conscious and able to swallow should be given 4 to 8 ounces (120 to 240 centilitres) of milk or water.^[1]  --Lambiam 20:53, 15 August 2023 (UTC)

120-240 millilitres, I think you'll find.... I'd be impressed if someone who has just ingested hydrogen peroxide was able to gulp down 2.4 litres of water. (Oh for the love of all that is holy, when will these pointless non-metric units finally die?) Fgf10 (talk) 22:45, 17 August 2023 (UTC)

If anything, a reducing agent would be more useful than a buffer. (Imho and Fwiw) 2601:646:9882:46E0:4579:586D:A5CF:72A3 (talk) 06:00, 16 August 2023 (UTC)

Under basic conditions H₂O₂ is itself a reducing agent, which suggests that making the stomach's pH more neutral might have some mitigating effect. However, I did not see this reflected in the literature.  --Lambiam 08:34, 16 August 2023 (UTC)

Stomach acid is pretty freaking acidic, though. pH = 1.5 to 3.5, at a volume of 20-100 mL. Taking the middle of those ranges (pH = 2.0 and 60 mL) you would need un infeasible amount of base. Indeed, the recommendation to "drink milk" after ingesting poison (a common folk remedy) is basically bullshit. --Jayron32 12:03, 16 August 2023 (UTC)

August 16

Baidana = bullshit?

Question about chain mail: I've known for a while about a type of chain mail called "baidana" ([2]), which was allegedly used by some Russian knights in the late Middle Ages, and which was made of large-diameter rings (much larger than normal, and so large that you can literally see through it). So, the question is, what's the point of such an armor? Because, due to the rings being so wide, it would offer no protection whatsoever against arrows and very little protection against stabbing attacks, and would also have less flexibility than normal chain mail (which would offset its admittedly lighter weight, which, along with its lower cost, are the only advantages I can see of this type of armor) -- am I correct? 2601:646:9882:46E0:4579:586D:A5CF:72A3 (talk) 06:37, 16 August 2023 (UTC)

The baidana said to be of Boris Gudonov seen here does not appear to have dramatically larger open spaces than typical chain mail. What is also important is the inner diameter of the rings, which should ideally be almost half the outer diameter. If D is the outer diameter and d is the inner diameter, the size of the open spaces is characterized by the value of 2d − D. I do not know to what extent longbows and pikes were used in medieval Russian warfare; a small size does not seem that important for protection in a sword fight. Perhaps some less effective forms of chain were meant to be used as part of a ceremonial dress.  --Lambiam 08:17, 16 August 2023 (UTC)

Looking at the image on that page, and the dimensions given, I don't think it would be very easy to get an arrow through the gaps. You have an 11 to 15mm inner diameter (depending on the armour), and much of that gap will be filled in with parts of the other rings. The rings are also thicker than I think is typical for chain mail, at least in the case of the with with 2.5mm thickness. So I expect they are improving strength (and probably ease of manufacture) at the expense of flexibility and protection against extremely narrow points. Also, they have prayers inscribed on the rings, granting a +1 Holy bonus to AC. Iapetus (talk) 11:51, 16 August 2023 (UTC)

WW2 attack fighters

Did any attack-fighters used in World War 2 have any kind of spaced armor, cemented and/or face-hardened armor? In particular, was any armor of this type (or indeed, any other than rolled homogeneous armor) ever fitted to any version of the Russian Il-2 or Il-10, even as a one-off experiment? 2601:646:9882:46E0:4579:586D:A5CF:72A3 (talk) 06:42, 16 August 2023 (UTC)

I can't speak as to one-offs, but I suspect the Ilyushin's design somewhat answers your question in the negative: it had a reputation as one of (or indeed, probably the) most resilient ground-attack aircraft of the war, with nicknames like the "concrete plane", "the flying tank", and "The Beast" in various iterations, and yet, according to this source, it seems to have only utilized conventional plating--just lots of it:

"The Il-2 was anything but advanced in its mixed wood-and-metal construction, which was relatively easy to manufacture in significant numbers using relatively unskilled workers. But for an aircraft, it was an amazing achievement. Among the Shturmovik’s most important assets were its strength and robustness in combat. The forward fuselage section — protecting the aircraft’s fuel system, radiators and crew station — was built entirely of armor plate. Thus, the Il-2 could, and often did, absorb extraordinary battle damage and survive to fight another day. The protective armor shell employed a special alloy developed for the Il-2; its thickness varied by location on the airframe. Special consideration had been given to a technology that would allow maintenance personnel to stamp the armor steel in the field, thus providing flexibility in the design, especially when Soviet units were forced to operate from primitive forward battle areas."

SnowRise ^{let's rap} 07:46, 16 August 2023 (UTC)

On the subject of armor for warplanes, it would be interesting to learn whether the WW2 Russian air force ever learned the following strategy. Conventional wisdom was to observe what areas of fighter planes that survive airborne dogfights get damaged most and to add armor to those areas. A later realization in the West was that strengthening other parts of planes reduced casualties more effectively because planes hit on those areas were never seen to survive. Philvoids (talk) 16:30, 16 August 2023 (UTC)

The source cited above does speak a little bit to this, and there does seem to have been some modular adaptation to such needs, but the Ilyushin was so often deployed for very low altitude strafing runs against reinforced positions, that it doesn't seem there were many places on the frame where it wouldn't take some degree of anti-aircraft fire. Similarly, there are some threats that no (realistic) amount of armour was ever going to significantly mitigate: for example, the greatest threat the the Shturmovik's safe return from a sortie seems to have been aircraft fire to the tail, owing to one weakness in soviet airpower relative to the luftwaffe: escort fighters. SnowRise ^{let's rap} 19:39, 16 August 2023 (UTC)

As I understand it, spaced armour was introduced to defeat high-explosive anti-tank ammunition which works on the shaped charge principle. Not much used against aircraft I imagine. Alansplodge (talk) 22:11, 17 August 2023 (UTC)

Not really in the same way, no--although there is a similar application of a proximity fuze for flak weapons. By the late Pacific campaign in particular, American vessels were using such weapons very regularly. But there the idea was just to get the ordinance to explode over a typically greater volume, since the primary challenge was just in hitting the target (generally much more vulnerable, but farther away, moving more quickly and with more maneuverability than your typical tank, needless to say), not in triggering the explosion to create a particular spacial and kinetic profile and the right distance, in order to penetrate primary armour. SnowRise ^{let's rap} 22:38, 17 August 2023 (UTC)

The way my source (which I'm trying to fact-check) describes the whole matter is, it describes a form of spaced armor where a projectile first strikes and pierces a thin piece of sheet metal, which causes said projectile to tumble and strike the main armor plate (tough and somewhat deformable, i.e. not face-hardened) at an angle, thereby causing said projectile to break and allowing the armor to absorb the energy of the fragments through plastic deformation -- and then it goes on to allege that such an armor was installed on (at least some versions of) the Il-10 and that it could stop a 20-mm armor-piercing round. So, the intention was (allegedly) to increase resistance to ordinary armor-piercing rounds, not shaped charges (which wouldn't be of much use against aircraft, given that they require a direct hit, which is hard to score against an aircraft even with guided missiles, let alone a flak cannon) -- but, from what I know about the Russians (this is a Russian-language source I'm trying to check), it doesn't look all that plausible (the physical principle seems sound, but I don't think the Russians actually used this system on the Il-10 -- the Russian design philosophy is all about ease of manufacture, so this seems too sophisticated for them, and they also have always been much given to empty bragging, so I wouldn't put it past them to have made up the entire thing out of whole cloth!) 2601:646:9882:46E0:C990:4871:79E0:D481 (talk) 08:42, 18 August 2023 (UTC)

You close your last post in very much a similar way to how I was preparing to respond having read the first part: that is, more specifically, I was going to say this all sounds more or less feasible to me, but I can find no indication in the sources I turned up which specifically validate that this happened with Soviet service aircraft on the Eastern front. The purported benefit you describe, while I cannot validate that it passes engineering muster, it does at least provide an alternative rationale for using spaced armor on a low-altitude operations aircraft. As you probably know, part of the reason for spaced armor was not just the dispersal of impact force ricocheting between the plates, but also the fact that tank-busting shells were designed to explode at a very specific range, creating a ballistic profile from the resulting fragments such as to maximize potential to penetrate the outer armor. The spaced armor therefore served to frustrate that function from anti-tank munitions.

As you say, this is not a fit for purpose when trying to take down an aircraft. By the end of the war, American vessels in the Pacific theatre especially were using flak shells that did have similar mechanisms for detecting nearby targets (some of the larger versions, utilized primarily to try to take down bombers in particular, employed radar, but there were other proximity fuze mechanisms as well). But regardless of the specific mechanism when these fuzes were triggered, there would be no guarantee (and indeed, little chance) that the shell was directly on course to connect with the aircraft, so directing the force of the explosion in one particular direction was not ideal. There was also less armor to penetrate in any event.

The ballistic profile was therefore more generalized (the stereotypical globular explosion of ship-based high explosive or shrapnel-based flak weapons--supported of course by batteries of AA guns using more traditional ballistic munitions (which were also being increasingly effectively coordinated by radar and interconnected/semi-automated firing patterns by the war's end). The Germans basically had none of these advantages though (they had experimented with proximity fuzes for almost as long as the British and Americans, if I recall correctly, but did not have it implemented in any widely used ordinance at any point in the war.

Anyway, the context with regard to your source's claims is much different: the Il-2 and -10 were low altitude attack craft often supporting infantry and armour divisions. Therefore they really would be especially concerned about the kinds of rounds contemplated in your source. Whether or not the mechanics of the spaced armour really translate to the proposed advantage is rather a difficult thing to speculate upon, but the fact of the matter is that I see no other sources so far that validate that it was attempted.

That said, the sources I did see were very clear that the manufacturing techniques for equipping and maintaining the armour of these planes was very much set up to be distributed and amenable to some degree of variation: the sources I saw seem to be suggesting that this was more about the logistics of machining the relevant sheets in fairly variable plant conditions, but the circumstances could have lent themselves also to some degree of experimentation.

So, if I was Snopes, I'd give this one an "undetermined"? It all adds up to possible (I mean, if nothing else, it could have been attempted and ended up being a terrible idea, or a mediocre idea that wasn't really thoroughly tested but which some engineers and field specialists bought into and continued to discuss for the remainder of and after the war). But as for direct confirmation in another source that it happened, I'm afraid I didn't find anything myself. SnowRise ^{let's rap} 09:28, 18 August 2023 (UTC)

Right, I'm thinking that if anything, this might have been (a) a one-off experiment with a modified Il-10 which was never tried again because the benefit was judged to be not worth the complication, or (b) a technology which the Russians did actually use in combat, but for tanks, not aircraft (spaced armor would make more sense for tanks in any case), and which the official propaganda then bragged about later as a standard feature of the Il-10, in order to showcase the supposedly unique advancements of Russian aircraft design. 2601:646:9882:46E0:C990:4871:79E0:D481 (talk) 11:07, 18 August 2023 (UTC)

August 17

Patterns for making "court" shoes with a block heel..

Does anyone here know of any 'free' patterns for these?

Alternatively does anyone know of any books on drafting patterns for footwear that are compatible with Wikimedia licensing policy? ShakespeareFan00 (talk) 10:05, 17 August 2023 (UTC)

• This 1885 book has some shoe patterns. Abductive (reasoning) 10:48, 17 August 2023 (UTC)

Transplantation into brain-dead bodies

There was a recent report on pig kidney transplant into brain-dead man in the US and surgeons claimed success stating that the transplant has continued to function for 32 days. Particularly, it was claimed that the kidney was not rejected in the minutes after it was transplanted. How on earth it's possible for a kidney to work in a brain-dead man? Seemingly, the question of organ rejection or acceptance isn't relevant for a dead man, to begin with. 212.180.235.46 (talk) 11:00, 17 August 2023 (UTC)

The brain was dead while the immune system not. Ruslik_Zero 11:21, 17 August 2023 (UTC)

I do agree that it seems the OP seems to be confused about the overall meaning of brain death, but it is worth mentioning, because of the very broad application of the term "brain death" (in the lay context and clinical environments both) that there are actually some immune functions that get some degree of mediation from the central nervous system. Of these (still somewhat nebulously described in some cases) mechanisms that I know of, I can't think of one that necessarily would create major concerns for a case study of this nature, but depending on the exact nature, but depending on the precise neuroanatomical nature of the brain damage and dysfunction, it's not entirely impossible--especially since inflammation response is a part of the pathways that may (again, very murky area) borrow some regulatory function from the parasympathetic nervous system and this is also a function of the immune response of concern for rejection. Of course, presumably those running this particular study either have dismissed the likelihood of impact in the case of such mechanisms and/or the particular damage in this case does not involve the relevant localized areas. SnowRise ^{let's rap} 14:18, 17 August 2023 (UTC)

See also Vegetative state, a person may have no higher-order brain functions, but their bodies may continue to maintain living otherwise, often for a very long time. --Jayron32 11:59, 17 August 2023 (UTC)

Ok. This says the brain-dead man is "being kept on a ventilator and other life supporting measures until the study concludes". To keep the kidney working I assume this includes some circulatory/cardiac life support and injection of water/fluids? 212.180.235.46 (talk) 17:31, 17 August 2023 (UTC)

In a sense there is direct circulatory support, but not of a mechanical variety, if that is what you are asking. First, it's important to understand that "brain death" has come to serve as a catchall for a span of different degrees of neuromorbidity. It may mean the loss of all higher cognitive functioning and any chance of a recovery of consciousness (but a still functioning brainstem), or it may involve the death of the brainstem as well (which is very typically the last portion of the brain to lose functioning if there is a cascade of damage to the brain). Increasingly there is a trend to push the term back to its original meaning (all lose of significant function, including the brainstem), but you still see a lot of variability out there--especially in lay literature.

In any event, if the brainstem is still functioning, autonomic functions may be maintained for some time. Once the brainstem no longer functions, however, the clock is ticking. This is where we get to your most recent specific inquiry: there is no need (or indeed, medically practical methodology) to force the circulation of the blood through the body once the heart has stopped beating. However, the heart contains its own pacemaker in the form of the sinoatrial node, and a broader system for transmitting electrical impulses through the heart to induce regular and rhythmic contraction (see cardiac conduction system). These systems are innervated and connected to the brain stem under normal circumstances (as are numerous other organs and metabolic pathways), so the system is by no means in a healthy spot once brain death (in the sense of brainstem ceasing to significantly function) has occurred, but so long as the heart continues to get an adequate supply of oxygen, it can continue maintaining a normal sinus rhythm for a while. This would typically require rapid intervention and intubation before the brainstem had lost all function, however.

In cases where the maintainance of the body after the point of true (brainstem included) brain death (which doctors will typically not want to do at this juncture, as there is zero chance of recovery, but may in the case of organ harvesting or when forced to by legal disputes), vasopressors and anticoagulants can be used to try to support cardiac function, but inevitably once the brain is no longer providing important mediatory functions for various systems, cardiac arrhythmias, widespread inflammation, and coagulation sets in. And that's just focusing on the circulatory system: other vital functions will be compromised and will accelerate the decline as well. Despite this, in some extreme cases, heart and lung function has been maintained for up to months at a time. But it is just a matter of time, and usually multi-system collapse will begin in a matter of hours or days, and all remaining respiratory, circulatory, and metabolic activity will cease. SnowRise ^{let's rap} 20:10, 17 August 2023 (UTC)

That's a revelation for me, thanks. 212.180.235.46 (talk) 09:29, 18 August 2023 (UTC)

You're most welcome! SnowRise ^{let's rap} 09:33, 18 August 2023 (UTC)

August 18

Crossing the desert

What survival equipment does one need when crossing the Sahara Desert? (Not planning to try this at home -- this has to do with a fictional scenario.) 2601:646:9882:46E0:C990:4871:79E0:D481 (talk) 08:47, 18 August 2023 (UTC)

By what method? (Otherwise I'd advise an aircraft as a sensible piece of equipment to use.) Bazza (talk) 09:35, 18 August 2023 (UTC)

I'm wondering how one would accomplish crossing the Sahara "at home". ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:55, 18 August 2023 (UTC)

As far as method of transportation I have in mind, the answer is, by camel caravan -- and the route is roughly from Tangier to Adrar, Algeria and thence to Tunis, so the total journey time would be about 2 months, give or take (same time as Google Maps theoretically gives for making the journey on foot -- but going on foot would be purely theoretical, because it's impossible to carry the amount of water one needs to survive that journey). 2601:646:9882:46E0:C990:4871:79E0:D481 (talk) 11:01, 18 August 2023 (UTC)

Whatever the mode of transportation, for ground travel one need not carry more than needed for each segment from one water source to the next. I know people who have crossed the Sahara in a Deux Chevaux, following the route from Algiers to Tamanrasset to Agadez (see route 2 in Trans-Sahara Highway) and then to Niamey. They travelled in "car caravans" – a row of cars travelling together so that assistance can be offered in case of a car breaking down – but the whole trip was not particularly challenging. On foot this is indeed not feasible; although the longest stretch without water sources is perhaps only 500 kilometres (310 mi), this will take close to two weeks and one needs to drink at least 2 litres (0.53 US gal) a day to keep hydrated, so one would need to cart some 25–30 kilograms (55–66 lb) of water.  --Lambiam 20:56, 18 August 2023 (UTC)

So, lots of water (obviously) -- what else? 2601:646:9882:46E0:CDC2:4F04:96FF:A0FE (talk) 01:59, 19 August 2023 (UTC)

Food. Travelling through the desert requires a lot of energy, both to enable one's metabolism to counteract the heat (and cold at night), and for the sheer effort of walking on rough or sandy footing.

One adventure thriller I recall reading hinged on discrepancies in an account of an earlier wartime escape across the Sahara. The protagonist realised that the account had been falsified to obscure the escapees apparent lack of sufficient food to make the actual journey, and deduced what their food source must have been. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 03:21, 19 August 2023 (UTC)

Survival Kit for Desert Travel. Alansplodge (talk) 09:17, 19 August 2023 (UTC)

All of these appear to be good ideas as far as basic survival (well, except that on one hand, fishing hooks and line are probably not necessary, because there are no fishing holes in the Sahara, and on the other hand, the supply of water purification tablets would have to be increased by a factor of at least 5, on account of the journey will take up to 2 months) -- but what about personal defense? Because in the Sahara (as opposed to, say, the Arizona desert), at least for a foreigner (like the characters I'm thinking of), dying of thirst is only the second-biggest danger! 2601:646:9882:46E0:A4C4:8081:B88D:5509 (talk) 01:53, 20 August 2023 (UTC)

Dying of thirst can only cease to be the worst risk if the traveller has a sufficient supply of water. Do you have a source for your implied claim that the local Bedouin pose a significant risk to the life of ill-prepared desert hikers?  --Lambiam 08:02, 20 August 2023 (UTC)

I thought I already said the travellers would be taking lots of water and a 2-month supply of purification tablets??? And as for the locals being a bigger danger than dehydration (at least to foreigners), how about this? 2601:646:9882:46E0:5D23:E078:A946:673 (talk) 08:35, 20 August 2023 (UTC)

The killers were not Bedouin. They were city dwellers. The place of the murders was hundreds of kilometres away from the desert.  --Lambiam 03:06, 21 August 2023 (UTC)

It was still a remote area within the same region, so the same principle would apply in the desert (only more so, given that if anything, law enforcement becomes less effective the farther away you go from the coastal areas!) 2601:646:9882:46E0:FCF1:5148:45CE:E9B3 (talk) 03:25, 21 August 2023 (UTC)

Considering the many things that could still go wrong, even with taking a supply of water and purification tablets (which don't help if you can't find water), I can't imagine many scenarios where the greatest danger is the risk of intentional harm from "locals". While there is some risk from "locals" where ever you are e.g. Murder of Ahmaud Arbery, with some places being more dangerous than others, we shouldn't overplay the risks either. Notably in the case of an actual ill-prepared desert hiker, it's quite likely an encounter with the Bedouin is more likely to save their life than end it. Nil Einne (talk) 12:38, 21 August 2023 (UTC)

Condition of road after plane crash

How did the road and street furniture in https://ichef-bbci-co-uk.cdn.ampproject.org/ii/AW/s/ichef.bbci.co.uk/news/800/cpsprodpb/500C/production/_130829402_malaysia2.png survive undamaged except for charring or soot after having a small plane directly crash into them? Thanks, cmɢʟee⎆τaʟκ 10:10, 18 August 2023 (UTC)

I'm not so sure the photo is sufficiently hi-def to draw that conclusion. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:28, 18 August 2023 (UTC)

Did a small plane crash here? The location is close to Rawang in Selangor state, Malaysia, looking south on the Guthrie Corridor Expressway that leads to the state capital Shah Alam and further south to the Kuala Lumpur International Airport. The photograph shows that emergency services have cordoned off a junction where we see widely spread debris. I cannot identify much but there are 7-8 crash responders gathered around what may be interesting (human?) remains at right where they have placed a red marker. It looks like the crash impacted somewhere off to the left of the scene and cast burning fuel over the whole scorched area. However the flare was too brief to leave other trace than to singe the grass at the road fork. Northbound traffic and crowds have collected at the incident on which we have no other information. Philvoids (talk) 17:36, 18 August 2023 (UTC)

There are plenty of news reports on the plane crash, which killed all eight people on board the plane, a Beechcraft Premier I, and two motorists on the ground. The opening shot of the video in this news report, taken from a side opposite to that for the photo in the BBC's article, shows still burning debris on the road as well as a significant smoke trail to the east. The latter is an area not visible in the BBC photo – although the charred ground can be seen up to where the left edge of the frame cuts it off and can be surmised to extend much further.  --Lambiam 20:10, 18 August 2023 (UTC)

A small plane isn't a missile or bomb. It doesn't have a warhead or explosives in it. Weapons designed to do things like crater runways or roads are actually rather specialized for the task. --OuroborosCobra (talk) 19:49, 18 August 2023 (UTC)

Now that you mention it, small planes are rather light and fragile. A paved road would likely do a lot more damage to a small plane than vice versa. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:50, 19 August 2023 (UTC)

Thanks, everyone. That makes sense! cmɢʟee⎆τaʟκ 16:40, 19 August 2023 (UTC)

P.S. Though that may trigger some 9/11 conspiracy theorists! cmɢʟee⎆τaʟκ 16:41, 19 August 2023 (UTC)

Had the terrorists flown small planes, they might have bounced off. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:35, 19 August 2023 (UTC)

The main damage was caused by all the fuel in the planes burning. they had taken off soon before. NadVolum (talk) 18:56, 19 August 2023 (UTC)

Yes. Essentially self-contained bombs. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:14, 19 August 2023 (UTC)

The plane was actually minutes from landing and crashed about 8.5 km (5.3 mi) from the runway of Sultan Abdul Aziz Shah Airport where it was headed, after more than an hour's flight from Langkawi.  --Lambiam 07:51, 20 August 2023 (UTC)

Don't know where I got they idea they were near the start of their flights. It still was the fires they caused which caused the iron to weaken leading to the collapse. The article says the impact and explosion of the fuel removed a lot of the fireproofing and started multiple fires. So worryingly the implication is that a smaller plane full of fuel might have the same effect on a similar building. NadVolum (talk) 08:59, 20 August 2023 (UTC)

American Airlines Flight 11 left the runway at 07:59 and crashed into WTC 1 at 08:46. It was headed from Boston to LA so was indeed fairly early on in its flight. (Our article doesn't give an expected flight time or landing time that I noticed, but Google suggests the normal time for such a flight is ~6 hours 10 minutes.) United Airlines Flight 175 took off at 08:14 (about the time AA 11 was being hijacked) and crashed into WTC 2 at 09:03. It too was headed from Boston to LA, so could also be said to be fairly early in its flight. The Beechcraft Premier I which crashed in Malaysia a few days ago was nearing the end of its flight as mention by Lambian. Nil Einne (talk) 12:05, 21 August 2023 (UTC)

Note that a plane near the end of its scheduled flight is nowhere near empty. ICAO fuel reserve requirements require extra fuel for at least 30 minutes' flight. cmɢʟee⎆τaʟκ 08:16, 22 August 2023 (UTC)

August 19

Swimming pool water

Dear RefDeskers. Having recently been to the swimming pool more often than not, I came upon this riddle.

Say we have an indoor pool of water, for simplicity, rectangular or square, regular, of a known width, breadth and depth, filled with regular water or any other liquid that might be suitable for the thought experiment. The pool is lined with tiles or any other impermeable material. For simplicity, we assume there are no water inlets or outlets or anything that might disturb the volume of the liquid. All other conditions (temperature, air pressure, etc.) standard. Now, we have some people splash around and then exit the pool. Given all the data above, and assuming that we can reasonably know any other measureable factors, is there a calculation that would allow us to determine how long it would take for the water to completely calm down and form an even surface, say, with a tolerance to +/ - 20 mm, +/ - 10 mm, +/ - 1 mm? Ouro (blah blah) 06:23, 19 August 2023 (UTC)

The kinetic energy of the people splashing in (which can be calculated using measurable data) is transferred to the waves, which will lose the energy by dissipation. I expect that there are well-known scientific laws that relate the energy of the waves to their amplitude and give the rate of dissipation.  --Lambiam 11:33, 19 August 2023 (UTC)

You have to consider the spectrum of the waves and the dimensions of the pool. Shorter waves dissipate faster. At the edges (sides and bottom), you get some non-linearities that can double or triple the frequency of a wave, transferring energy from long waves to short waves. Full hydrodynamics simulations are hard, but can be done reasonably well today. For the amateur researcher, I think an experiment is a lot easier. PiusImpavidus (talk) 10:12, 20 August 2023 (UTC)

What animals need to feed at least every 12 hours.

If a zoo was unable to feed its animals between Midnight and Noon every Tuesday, what animals would be significantly negatively impacted? I figure it would kill the hummingbirds, but some animals like snakes that are on the other end of the scale (My local park service only feeds the snakes in its exhibit house on one day of the week). Are there any mammals that have to eat that often? (Grazers like cows?) Naraht (talk) 16:09, 19 August 2023 (UTC)

Mouse? Ruslik_Zero 16:24, 19 August 2023 (UTC)

Shrew, probably. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 17:53, 19 August 2023 (UTC)

Here’s the guideline for zoo animal feeding in India. They might feed large carnivores ground meat daily, but they give them large bones or rabbits weekly to maintain teeth and jaw muscles. There might be concern of large aggressive carnivores turning cannibal if they get as hungry as they do in nature, days after the last feeding. Nursing mother carnivores might be fed daily but other large carnivores in nature may eat big meals days apart. Baby animals and recently hatched animals need frequent nutrition. As noted, reptiles might go days without feeding. https://www.ndvsu.org/images/StudyMaterials/Nutrition/Feeding-Schedule-Wild-Zoo-animals.pdf Edison (talk) 18:33, 19 August 2023 (UTC)

An animal can eat more often than the zoo feeds it, as some food can be stored in the animal's enclosure. Hummingbirds consume nectar regularly from flowers, artificial or natural. The artificial flowers get refilled once a day, the natural flowers get cared for like any other plant. Grazers can eat the grass growing in their enclosure. If there's enough grass per grazer (unlikely), the zoo doesn't have to feed them at all. PiusImpavidus (talk) 10:33, 20 August 2023 (UTC)

An acre (a square 208 point something feet wide) is apparently enough for 2 sheep without keeping them in a revolving subset of that acre in which case an acre can feed a lot more. Sagittarian Milky Way (talk) 12:22, 20 August 2023 (UTC)

The usual way to envisage an acre is a furlong by a chain, or 220ˣ × 22ˣ. For those who can't understand the units: 660 by 66 feet (201 m × 20 m). I'd wonder about the asserton that an acre could feed two sheep though, are we talking about an acre of sweet, lush lowland grass, or an acre of high moorland? Martin of Sheffield (talk) 14:18, 20 August 2023 (UTC)

Or, a standard US football field (not including end-zones) is almost exactly one acre -- 1.094 acres to be precise. 136.54.106.120 (talk) 19:09, 20 August 2023 (UTC)

"a good rule of thumb is 10 ewes and 15 lambs per acre of pasture. This assumes that you will be using a well-executed rotational grazing regimen" DuncanHill (talk) 14:31, 20 August 2023 (UTC)

Because that was the shape of the pre shape-agnostic acre cause their plow animals could only sustain about 10 chains between rests and that was a convenient shape (less plow-turning but not inconveniently skinny). I'm a New Yorker so I think of an acre as a Twin Tower footprint or the end of a skinny Manhattan-style block (enough lots to be 200x200 (8 pairs, 10 pairs in Manhattan). There's also lots of 100x100 buildings i.e. many 1-story supermarkets. Most Chicago blocks are 1 furlong square with a bisecting alley so an acre's exactly 20% the land between road centerlines. When I was there I "obviously" had enough time to walk from the cross-country buses to the lake and back but soon realized their street gaps are bizarre. And that is why I've been to Chicago's core but not Lake Michigan. Sagittarian Milky Way (talk) 00:42, 22 August 2023 (UTC)

Where would light emitted from a reference frame unaffected by a more complete and comprehensive energy source collapse?

I was reading and began to wonder where would light emitted from the most bright collapse inside the ocean go for a warmer reflection up to the speed of light? I know that there can even be waves that would go far as to ever really reach an energy output equivalent to the most powerfully massive black hole, but how would this affect the most brightly reflective inertial frame when it even has a difference beyond what would actually ever terminate? Drishithan (talk) 21:38, 19 August 2023 (UTC)

There are at least six places in this query that combine words in ways that make no physical and/or grammatical sense. If this is not a spoof, I suggest, Drishithan, that you find someone with a better command of the English language and grasp of physics to translate it from whatever language you usually speak. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 01:11, 20 August 2023 (UTC)

I used that query as an AI copilot prompt and had it rephrased for clarity, with the following result:

While reading, I started to ponder where the light emitted from the brightest source would go if it were to reflect off the ocean with enough energy to reach the speed of light. I am aware that there may be waves that could reach an energy output comparable to a massive black hole, but I am curious about the impact on the highly reflective inertial frame beyond its termination point.

Using that as a prompt I asked Perplexity.AI to explain, resulting in:

Based on your question, it seems you are wondering about the impact of highly reflective inertial frames beyond the termination point of light reflected off the ocean with enough energy to reach the speed of light. While the specific scenario you described is not directly addressed in the search results, I can provide some information on inertial frames and the behavior of light in different reference frames.

1. Inertial Frames: An inertial frame is a reference frame in which the motion of a body not subject to forces is always rectilinear and uniform. In an inertial frame, the center of mass of a closed system of interacting bodies is always at rest or in uniform motion^1,3 Any other frame of reference moving uniformly relative to an inertial frame is also considered an inertial frame¹

2. Light Propagation in Inertial Frames: According to the principle of light speed constancy, light propagates at the same speed, denoted as "c," in all inertial frames⁵ This means that the speed of light is independent of the motion of the source or the observer. The distance traveled by light in a given time interval is always the same, regardless of the reference frame⁵

3. Reflection of Light: When light reflects off a surface, such as the ocean, its angle of incidence is equal to its angle of reflection. The reflected light follows the same laws of reflection in all inertial frames⁵

Based on this information, it can be inferred that if light emitted from the brightest source were to reflect off the ocean with enough energy to reach the speed of light, its behavior would follow the laws of reflection in the inertial frame. The highly reflective inertial frame beyond the termination point of the reflected light would experience the same laws of reflection as any other inertial frame. It's important to note that the specific scenario you described involves light reaching the speed of light, which is not possible according to the principles of special relativity. The speed of light in a vacuum is considered the maximum speed in the universe, and objects with mass cannot reach or exceed this speed⁴

Please let me know if there is anything else I can assist you with.

-- 136.54.106.120 (talk) 09:48, 20 August 2023 (UTC)

Ha ha ha! Oh dear I shouldn't have laughed and me with this pain all down the diodes on my left side ;-) NadVolum (talk) 10:12, 20 August 2023 (UTC)

Yeah, this is another one of those previews of our future sidelined and observing AI's talking to one-another that is equal parts worrisome in the abstract and yet also reassuring that it clearly isn't going to happen immediately. SnowRise ^{let's rap} 00:45, 21 August 2023 (UTC)

August 20

Why do we lack articles on so many species?

I know this is not the most appropriate venue but I am not likely to generate a discussion anywhere else. Has anyone else noticed that the science side of Wikipedia is underdeveloped compared to the humanities topics? It seems to me that Wikipedia is missing articles, even stubs, on a vast number of species, including those described over a century ago and well-known among hobbyists. Surtsicna (talk) 19:06, 20 August 2023 (UTC)

For one thing, there are Eight million, seven hundred thousand species! (Give or take 1.3 million.); as for Wikipedia editors: Only a minority of users contribute regularly (116,367 have edited in the last 30 days).

Also, Wikipedia is not, and never can be complete. You are more than welcome to give it a try!

There might be something in Portal:Biology of interest, or you could join a relavant Wikiproject. -- 136.54.106.120 (talk) 19:40, 20 August 2023 (UTC) . . . P.s: Although not assigned as a bot at birth, today I am self-identifing as one

Fundamentally, it is because most species are unencyclopedic. In the case of vascular plants, there are something like 350,000 species, but only about 73,000 species articles. I did a little study and found that there are about 5,700 wrongly titled or synonymized species articles on en.Wikipedia, or 8.5% of all species articles. Why? Because polbot and misguided users think that most species are important—they are not—and mass-creating stubs that are nothing but database entries is worse than not creating them. Abductive (reasoning) 20:25, 20 August 2023 (UTC)

Additionally, these articles tend to be a little labour intensive, I can say from some small experience. Finding reliable sources that pass muster for scientific topics and allow you to flesh out all of the details expected for even a basic summary of the species features (anatomy, behaviour, ecological niche, range, taxonomy) can be difficult--and certain impossible for many little known species. And then you undoubtedly want a photo or six to illustrate your subject, so you have to do an extensive search to find something already authorized under the appropriate license, or else communicate with the owner of the images and try to convince them to license the photo(s) appropriately. Then there's typical new page patrol reviews and tagging and polishing, maybe some of the more borderline sources you decided to go with for this or that aspect of the article gets challenged. And everything I am describing here is for a relatively modest article regarding a non-charismatic species, which are the only type I have authored myself. I assume it's even more complicated to do new semi-popular species that might have popped up in the mainstream, even if you do get to distribute the work a little. SnowRise ^{let's rap} 21:48, 20 August 2023 (UTC)

Oh, how I sympathize, Snow Rise. Somehow I am always prouder of the photographs I manage to procure than of the text I compile. (Look at these!) Still I am puzzled when I find topics such as Clerodendrum bungei, Poecilia kykesis, Xiphophorus milleri, Xiphophorus pygmaeus, etc, for which there is a ton of readily available literature and a decent amount of popular interest yet nothing but a red link for over 20 years of Wikipedia's existence. Surtsicna (talk) 13:19, 21 August 2023 (UTC)

And the humanities are probably not over represented. Instead we have popular culture well represented. When it comes to biographies, people are keen to write about themselves. For companies or products, advertisers are paid to promote them, so there is a strong motivation to put these kinds of topics in Wikipedia. Compare species articles with numbers of articles on former companies, or dead people. Then we get articles on fossils for which a species may be supported by one bone, and one publication. Graeme Bartlett (talk) 22:45, 20 August 2023 (UTC)

Good point. If I consulted a few-decades-old edition of the International Directory of Company Histories from Gale, I suspect I'd find heaps of companies with no Wikipedia articles, and yet I could probably find enough dead-tree coverage to create articles on them easily. Nyttend (talk) 06:48, 22 August 2023 (UTC)

August 21

Icequake

How much methane would it take to either (a) cause an explosion of Earth's entire atmosphere, or (b) explode with the same energy as that of the biggest volcanic eruption which had ever happened in Earth's history? Would it be possible for this amount of methane to be released into the atmosphere if either (a) all of the permafrost in Alaska had melted, or (b) if all permafrost in the entire world had melted, or (c) if all of the methane from all sources (including deep-underground sources) had somehow escaped into the atmosphere? 2601:646:9882:46E0:419:F6DA:6858:7015 (talk) 04:38, 21 August 2023 (UTC)

You need at leats 4.4% in volume of methane in air to get an explosion. The density ratio of methane to air is about 16:29 and the Earth has about 5.15·10¹⁸kg of air, so that's about 1.25·10¹⁷kg of methane. Our article on methane clathrate mentions 5–25·10¹⁴kg of carbon in methane clathrates on the sea floor, 2.3·10¹⁴kg of carbon in natural gas reserves, 4·10¹⁴kg of carbon in methane clathrates in permafrost in the Arctic (only a small fraction of which is in Alaska) and an unknown amount in permafrost in the Antarctic. The mass of methane is 5/4 times that of carbon. Even the highest estimates are a factor 32 too low to cause the entire atmosphere to explode. The resulting greenhouse effect would be more than enough to worry about.

We don't know that much about the biggest volcanic eruption in the Earth's history. Very little is on record about volcanic eruptions more than 100 million years ago, big eruptions don't put out all their energy in a single explosion, some don't explode at all but just produce a lot of lava. PiusImpavidus (talk) 10:33, 21 August 2023 (UTC)

Thanks! So, the answer to the first question is "no" -- but would it be possible for methane in the atmosphere to explode with the same energy as the total energy of the eruption(s) which created the Flat Landing Brook Formation? Because an explosion of that size (whether methane, volcanic or otherwise) would indeed cause total devastation within a wide region (in fact, it would make the Tsar Bomba seem like a firecracker!) 2601:646:9882:46E0:AC4B:990B:D3F3:99DE (talk) 10:53, 22 August 2023 (UTC)

Animals' evolved fear of humans

I hhavevheard that wild animals avoid humans, so as long as humans don't go looking for trouble, there is little reason for us to need to carry weapons to kill them. But I wonder, since instinctual avoidance of humans can't happen for no reason at all. If humans stop hunting bears and wolves, will the avoidance of humans decrease over time? I'm supposing that any species can quickly evolve a fear for another particular species, as a handydevice in the genetic toolkit, and also deevolve the fear if it stops being selected for.136.36.123.146 (talk) 04:55, 21 August 2023 (UTC)

Actually, instinctual avoidance of humans does happen for no reason at all. In any group of animals, there will be a wide range of natural responses. Some will approach humans with no fear, perhaps with curiosity. Some WILL show fear. And such behaviour is at least partly hereditary. If the humans do pose a threat, the animals they kill will be those who showed no fear. Those who were fearful and held back, may survive, and pass that successful gene onto their offspring. HiLo48 (talk) 06:20, 21 August 2023 (UTC)

Apart from instinctual avoidance of humans, there's also learned avoidance. The wild animals may see others of their group killed by humans, may be non-lethally hurt by humans or humans may simply do unexpected things, making the animal feel less in control. If uncertain, stay away.

Having said that, wolves have recently returned to Western Europe and it turns out that they're not particularly afraid of humans, certainly less so than when they were actively hunted 150 years ago. Some nature photographers threw down some meat on the heath to get a nice picture of a wolf and one of those quickly learned that humans can be an easy source of food and began approaching, reportedly even chasing, humans. PiusImpavidus (talk) 11:09, 21 August 2023 (UTC)

Unlike the wolves there are still many easily-spooked horses thousands of years after they stopped being eaten by the megafauna that made them paranoid. I've noticed that roaches have different personalities, some freeze and let a fingertip pad creep well inside guaranteed hand pounce range before they switch their "strategy" to flee. The most scared flee like maniacs before I've even walked within reach much less started reaching yet. I think I'm unintentionally increasing mean roach fear and lowering the percent of medium to low fear. Sagittarian Milky Way (talk) 22:13, 21 August 2023 (UTC)

To be fair to horses, it wasn't that long ago that we stopped eating them (much, I've eaten horsemeat in Belgian restaurants). Their domestication is thought to have begun by their being corraled as a meat and milk animal, before we learned how to ride them and later use them as draught animals. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 13:04, 22 August 2023 (UTC)

Oort cloud size

Oort cloud#Stellar perturbations and stellar companion hypotheses remarks that The orbit of the Sun through the plane of the Milky Way sometimes brings it in relatively close proximity to other stellar systems. If the Oort cloud is as great as 3.2 light years in diameter, and Alpha Centauri is 4.2465 light years away, how are the farthest-out Oort cloud objects not attracted away by Alpha Centauri and other nearby stars? Is it simply a matter of the Oort cloud objects not being in the right place at the right time (e.g. they're on one side of the Sun and Alpha Centauri is on the other, 7.5 light years apart), or is there some better explanation? Of course I understand that the Sun could hold onto its comets against Alpha Centauri if it has a greater gravitational pull, but the two stars' infoboxes use different mass measurements (the Sun is 1.9885×1030 kg and Alpha Centauri is 1.0788±0.0029 M☉), so I'm unclear which is larger. Nyttend (talk) 22:44, 21 August 2023 (UTC)

M☉ means mass of sun, so 1.0788±0.0029 M☉ is bigger. However, even if gravity attracts an object, it is moving with an initial velocity, and then is probably in a hyperbolic orbit, and will then escape from the gravity of the attractor. It may be scattered in some direction away from the path of the Sun, and then be lost from the cloud. Graeme Bartlett (talk) 23:52, 21 August 2023 (UTC)

Oort cloud actually mentions a radius of 3.2 ly, not diameter, so your doubt makes sense. A footnote tells that this number is vague and and could also be a factor 4 lower. The radius is defined by the Sun's Hill sphere, which varies as visiting stars come and go.

α Centauri is a triple star system with a combined mass of 2.11 M☉, at a distance of about 4.2 ly from the sun. That gives the Sun a Hill sphere with a radius of about 2 ly. An object at 3.2 ly from the Sun in the direction of Centaurus cannot be currently gravitationally bound to the Sun. In the opposite direction, towards Perseus or Cassiopeia, the energy of such an object would be more than enough to escape to the α Cen system, but by the time that this object in its chaotic orbit reaches the saddle point, α Cen will be long gone and the Sun's Hill sphere may have grown. Objects at 3.2 ly from the sun still have a good chance of returning to the inner solar system. Obviously, Oort cloud objects get lost to interstellar space all the time. Similarly, if α Cen has its own Oort cloud, the Sun could steal comets from there.

Nobody has ever observed an object in the Oort cloud that far away. Even a big one can only be observed when it approaches the sun to within a few lightdays (in which case it's no longer in the Oort cloud). PiusImpavidus (talk) 09:07, 22 August 2023 (UTC)