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November 29

How can a magnet be used to alter a current?

Current through a circuit, like a flashlight, and current through a wire? So that's DC and AC. Magnets can interfere with the electromagnetic field, right. 67.165.185.178 (talk) 05:27, 29 November 2021 (UTC).[reply]

That's right. Dynamos and Power stations use magnets to generate electrical current. Do you have a more specific question?--Shantavira|^{feed me} 09:22, 29 November 2021 (UTC)[reply]

Yea, but I don't think electric current is the word I'm looking for, that makes it seems like magnets create or destroy electricity from nothing. 67.165.185.178 (talk) 14:01, 29 November 2021 (UTC).[reply]

Electric power plants make electricity by spinning one or more magnets near large amounts of wire, if the motion stopped the electricity would turn off. Sagittarian Milky Way (talk) 17:17, 29 November 2021 (UTC)[reply]

Okay, now I know what my communication problem was. I'm talking about placing a magnet near it, not placing a spinning magnet near it. 67.165.185.178 (talk) 09:04, 30 November 2021 (UTC).[reply]

There's the Hall effect. PiusImpavidus (talk) 09:49, 30 November 2021 (UTC)[reply]

If you have a battery making 1 volt and amp at the Hall conductor and create the Hall effect with a static permanent magnet and try to get extra power from the Hall effect with a second loop of wire will it work? Does the battery circuit have to reduce wattage to keep the sum of the 2 circuits from exceeding 1 watt and breaking conservation of energy? Sagittarian Milky Way (talk) 15:17, 30 November 2021 (UTC)[reply]

It still has to move, if you are making enough electricity you will feel resistance, that's where the energy comes from. Sagittarian Milky Way (talk) 14:43, 30 November 2021 (UTC)[reply]

Resistance, from a spinning or non-moving magnet? 67.165.185.178 (talk) 14:51, 30 November 2021 (UTC).[reply]

If you wave a conductive armillary sphere back and forth near a powerful enough magnet it'll push back like it wants to be static. Sagittarian Milky Way (talk) 15:17, 30 November 2021 (UTC)[reply]

Whether the current is DC or AC depends on the power source. Flashlights typically operate on batteries, which are used to power DC circuits. The current through a wire can be of either type. Faraday's law of induction describes how a magnetic field interacts (a more neutral term than "interferes"; the interaction can be useful) with an electric circuit. It requires the magnetic flux to vary in time. A stationary permanent magnet has no effect on a stationary electric circuit. --Lambiam 11:31, 29 November 2021 (UTC)[reply]

Weird, I thought magnets influence DC motors more than AC motors? 67.165.185.178 (talk) 14:01, 29 November 2021 (UTC).[reply]

What kind of influence are you thinking of? Among electrical motors, the difference between motors powered by DC sources and AC sources is slight; the former type has an additional commutator that makes the direct current appear to the coils of the motor as if it alternating. It is not apparent to me why that difference should be of any importance when magnet enter the scene. --Lambiam 23:51, 29 November 2021 (UTC)[reply]

Okay here's an answer I got from a retired electrical engineer: for dc motors, the magnetic flux lines have to intersect a coil of wire at the correct angle at a certain rate of speed, while alternating north and south poles to excite electrons in the wire coil to create measurable current flow. a motor just reverses the process. ac motors are a little different. alternating current is always rising and falling the magnet would have to be synchronized in reversing poles to affect the ac motor. 67.165.185.178 (talk) 05:53, 30 November 2021 (UTC).[reply]

@Sagittarian Milky Way: Here is what the retired electrical engineer responded to your question to PiusImpavidus: hall effect devices are simply a magnetic switch in a solid state form. essentially an electronic reed switch. it's a make or break device. not capable of making current or voltage, merely to control it. can use it to control a circuit such as a servo feedback sensor or like in a car engine for crankshaft position sensor. 67.165.185.178 (talk) 19:06, 1 December 2021 (UTC).[reply]

November 30

Rockets with solid rocket boosters launching crewed spacecraft

One of the reasons Ares I was canceled was because it was determined that launching a crewed spacecraft on a solid rocket was unsafe. Similarly, the Space Shuttle's SRBs were considered unsafe (and given that the Challenger disaster happened, those fears had basis). However, the Boeing Starliner is launched on the Atlas V in a configuration that uses solid boosters; similarly, the cancelled Hermes spaceplane was planned to be launched on the Ariane 5, which also uses solid boosters. How come launching crewed spacecraft on solid rockets or rockets with solid rockets is often considered unsafe, but this was not considered to be the case for the Atlas V launching Starliner? Is it the size of the boosters, or is it another factor? Narutolovehinata5 (talk · contributions) 00:19, 30 November 2021 (UTC)[reply]

As far as I am aware, the cancelation of Ares I had nothing to do with safety concerns of the SRBs. In fact, Ares I was seen as having a potential higher safety rating than EELV launchers, such as the Atlas V. --OuroborosCobra (talk) 00:30, 30 November 2021 (UTC)[reply]

According to this Scott Manley video, one factor for the cancellation of the Constellation program was that an Air Force study claimed that if there was a need to abort due to a problem with the rocket (i.e. an explosion), the capsule's parachutes would be burned by burning debris. Narutolovehinata5 (talk · contributions) 00:45, 30 November 2021 (UTC)[reply]

The supposed safety rating of Ares 1 was widely mocked in the community. Aside from the parachute burning through issue mentioned above, there was also a significant issue with thrust oscillation (example link from the time), potentially subjecting the crew to significant G forces several times a second, to the point that there were serious worries about crew performance. Towards the end of the programme they were discussing madcap schemes such as upward firing thrusters to compensate.

I don't know if solid boosters are less safe: they are just way less efficient (have lower specific impulse) than liquid boosters. The Space Shuttle SRB failure resulted from notoriously ignoring signs of burn-through in the O-rings, which in turn resulted from human normalization of deviance within the contracting organization. Liquid boosters can also be throttled, turned on and off, etc., unlike solid boosters that are basically giant sparklers that can't be extinguished once lit. But if anything, liquid boosters are less reliable than solid boosters, because of the complicated turbines, pumps, cryogenics, etc. in them. Remember also the near-fatal LOX tank explosion on Apollo 13.

The US crewed spaceflight programs prior to the Shuttle all used liquid boosters, but (iirc) 1960s-70s Soviet crewed launches used supplemental solid boosters similar to what the Shuttle eventually used. I suspect this was because NASA was by then better equipped than the Soviets to surmount the hellishly difficult technical challenges of making cryogenic boosters (particularly using liquid hydrogen) reliable. 2601:648:8202:350:0:0:0:69F6 (talk) 00:34, 30 November 2021 (UTC)[reply]

As a correction, the Vostok/Voshkod/Soyuz boosters all use kerolox engines, they never used solid rockets to launch crew. Even the Buran's boosters (which were later adapted into the Zenit rocket) used kerolox, not solid propellant. Narutolovehinata5 (talk · contributions) 00:47, 30 November 2021 (UTC)[reply]

Let's not forget per-spaceflight JATO units and the shenanigans people got up to with those. See the JATO_Rocket_Car urban legend. 41.165.67.114 (talk) 06:19, 30 November 2021 (UTC)[reply]

Or the supposedly real Jet powered Volkswagen. 2601:648:8202:350:0:0:0:4F12 (talk) 08:13, 30 November 2021 (UTC)[reply]

Also I'd like to reply here that Soviet rocket engine engineers were by no means inferior to American ones, as the IP above seems to imply. They just chose a different path. Their oxygen rich staged combustion kerosene-oxygen engines were so far ahead of what the West could do, their specs were thought to be incorrect when they were first revealed to the west after the Soviet Union went down. (See for instance the excellent "The engines that came in from the cold"). Given the general move away from hydrogen (booster) engines in new developments, one could quite easily argue they went down the right path. Fgf10 (talk) 12:44, 30 November 2021 (UTC)[reply]
- The Soviet engineers weren't inferior by any means. They just didn't have NASA's technical infrastructure or budget at their disposal. And as Naruto mentioned, they did use liquid (kerolox) boosters as did the first stage of the Saturn V, though maybe not LH (like the Saturn V 2nd stage) which was more difficult. Anyway, in that era, quite a few important NASA engineers (such as von Braun) were German. It is likely the case, though, that the US (through Operation Paperclip) had better access to the leftover German rocketry leadership and tech, which was still relevant as late as the 1970s. 2601:648:8202:350:0:0:0:4F12 (talk)`

December 1

Mechanical durability of RFID tags

Today, at least in Sweden, we use RFID tags for "everything", especially for unlocking doors (so a tag is used instead of a traditional, dumb metallic key). At least I do believe that "RFID tag" is the proper name for this kind of thing, even though the Wikipedia article on RFID tags doesn't contain a single image of the kind of tag I am talking about (although one image comes close).

In any case, I am interested in the mechanical durability of these things. For example, being rather clumsy, I regularly drop my keys (dumb metallic ones + RFID tags) on the floor. Fortunately, I am not excessively tall, so the distanced travelled during the fall never exceeds 1.2 metres. But the floor may be made of stone.

Can such a fall destroy an RFID tag? --Andreas Rejbrand (talk) 20:25, 1 December 2021 (UTC)[reply]

I assume this is a passive RFID tag (no battery on board). An RFID tag is a very thin circuit and would be extremely delicate if not attached to a substrate. Many materials that can form a layer can serve for this purpose, provided they are not conductive themselves, including paper. For an RFID tag that serves as a key and has to be handled many times, a common approach would be to embed it in a plastic casing, giving it a form factor like a casino chip or a key fob. For obvious reasons, the material should be neither brittle nor extremely pliable. One approach is paper laminated with PVC, as is common for plastic cards. The PVC is relatively rigid and the lamination gives increased strength and crack resistance, but the lamination may come undone. A casing made of ABS, also relatively rigid but more durable and with excellent properties such as impact resistance and toughness, may be more common. In either case, as long as the casing does not crack, the embedded RFID tag should survive falls and other mishaps. --Lambiam 23:16, 1 December 2021 (UTC)[reply]

Thank you for your answer. It seems like I don't need to worry too much about this. --Andreas Rejbrand (talk) 20:17, 3 December 2021 (UTC)[reply]

Resolved

December 2

Without buoyancy, are raindrops becomes heavy than normal?

Without buoyancy , are raindrops becomes heavy than normal? Rizosome (talk) 09:08, 2 December 2021 (UTC)[reply]

No. Buoyancy does not affect the mass (or weight) of anything.--Shantavira|^{feed me} 11:36, 2 December 2021 (UTC)[reply]

It is not uncommon to find statements in popular science texts such as, "A crown weighs less when immersed in water than it weighs in air."^[1] But this is not correct when using the scientific definition of weight, which is purely the force due to gravity. It would be correct to say that it feels less heavy. Weight cannot be measured directly. What can be measured is the force of reaction needed to keep a body stationary while it is subject to an action force. That is what a weighing scale does. The action force on a body immersed in a liquid is the force of gravity minus the buoyancy. If the density of the liquid is very small compared to that of the body, it may be ignored – as is usual for a person (with a density about 800 times that of air) stepping on a scale that is not very precise anyway. --Lambiam 12:28, 2 December 2021 (UTC)[reply]

"Weight" is actually inconsistently defined. There have been some people who insist (but it turns out, very few actually use in practice) the "weight = force of gravity" definition, even as it turns out, actual practicing physicists. You've just implied three different definitions of weight (weight as synonym of mass, weight as force of gravity, weight as "force of reaction" (i.e. normal force) on a scale). All three get used in different contexts, often without elaboration as to which the speaker means. We even invented the concept of "mass" to avoid these differences in definition, but it turns out even that has problems; inertial mass and gravitational mass were tantalizingly the same thing every time we measured them, but no one could come up with a way to prove they were the same thing until general relativity. The real issue is that when we try to create precise, unambiguous definitions, we run into the two distinct problems of language and measurement. Language is fundamentally ambiguous; there is no natural human communication system which is capable of perfect precision, and that includes scientific nomenclature. And regardless of how you define something like "weight", the most precise definition suffers from a lack of reasonable physical means to actually measure it, which means that as it becomes more precise, it becomes less useful. For example, if we want to accept that weight is the force of gravity alone, ignoring all other forces, then how can you devise a practical scale to measure that? You can only actually measure the normal force using such a scale, and the normal force is approximately the force of gravity, but never the force of gravity alone. --Jayron 32 13:30, 2 December 2021 (UTC)[reply]

From our archives:

Is Weight a Net Force? (2017)
Quarks ... and discussion on the units we use to measure mass (2010)

To throw some fuel on this fire - are astronauts on the International Space Station subject to "zero gravity," "microgravity," or "almost the same amount of gravity as someone on the Earth's surface"? I think the answer depends on whether you're discussing the topic with schoolchildren, ...with their teachers, or with spacecraft design engineers. Pilots and astronauts, being very task-saturated during calculation of their G forces, say they get to zero-G here on Earth, presumably due to the buoyant force of phlogistan that ebbs and flows in This New Ocean. Nimur (talk) 17:54, 2 December 2021 (UTC)[reply]

The concept of weight can be divided into apparent weight and actual weight, also called true weight. The former takes buoyancy into account. A piece of wood under water or a helium balloon in air even have negative apparent weights. If you immerse a scale in a swimming pool and weigh yourself you'll find the scale measures apparent weight (unless you have a scale with an unusually convoluted mechanism). 85.76.71.10 (talk) 14:57, 2 December 2021 (UTC)[reply]

You can do all kinds of things. It's just refinements on top of refinements on top of refinements, and again, precision and usefulness work at cross purposes here. One more thing worth mentioning is that, one of the other main problems with the re-definition of weight as "the force of gravity" is that such a definition was basically created out of thin air for no real reason, it seems. We already have a perfectly usable term for the force of gravity. It's called "the force of gravity". It works great, there's no reason to appropriate another word and make it a synonym for the force of gravity if you just mean the force of gravity anyways. Weight as a concept is a far older thing than is mass, and it didn't mean the force of gravity, it meant "how heavy is this thing" and you measured how heavy it was by putting it on a scale. It's a perfectly good functional word for that purpose, and we do a disservice to all when we insist that it now means "the force of gravity and nothing else", especially when the term "the force of gravity" already means that. See here, the sense of weight as a measure of heaviness dates to Old English. There was no good reason to insist that it meant something else once we tried to separate the meaning from "mass", which in the sense of "that thing we measure in grams" only dates from 1704. --Jayron 32 15:08, 2 December 2021 (UTC)[reply]

A raindrop feels 0.1% heavier in hydrogen but the mass stays the same. Sagittarian Milky Way (talk) 15:17, 2 December 2021 (UTC)[reply]

@Shantavira: If Buoyancy does not affect the mass (or weight) of anything. Then, how ship won't sink in water or ice berg won't sink in water? Rizosome (talk) 01:41, 3 December 2021 (UTC)[reply]

Whether a heavy ship or other body will sink depends on its apparent weight, which is its actual weight (its mass multiplied by the local gravitational acceleration) minus the buoyancy (which its the weight of the displaced water – see Archimedes' principle). For a ship floating in water these two forces have equal magnitude and so they cancel each other: the ship has an apparent weight of 0 N. That the ship is actually still quite heavy becomes apparent when you try to lift it out of the water. That it has considerable mass is apparent when you try to halt the moving ship, merely coasting after its motors stopped. --Lambiam 06:18, 3 December 2021 (UTC)[reply]

And the iceberg floats because ice is less dense than water. Tigraan^{Click here for my talk page ("private" contact)} 08:32, 3 December 2021 (UTC)[reply]

I still don't understand the original question. What does any of this have to do with raindrops?--Shantavira|^{feed me} 10:43, 3 December 2021 (UTC)[reply]

The original question asked about heaviness, an imprecise term, that can refer to either density, mass, or weight depending on context. Terms like mass and weight are also themselves imprecise terms, and the follow-on discussion was about teasing out those complexities. Without the buoyant force of air, raindrops (and everything else) would drop faster. The OP, however, asked if they would be heavier, which because such a term has multiple meanings, depends on what one means by "heavy". --Jayron 32 11:52, 3 December 2021 (UTC)[reply]

Due to complexity involved, I considered it my question as open question in physics world : Terms like mass and weight are also themselves imprecise terms, and the follow-on discussion was about teasing out those complexities. Rizosome (talk) 02:03, 4 December 2021 (UTC)[reply]

Resolved

Why is a single paper about fossil turtles cited with dates 2016 sometimes and 2017 other times?

My question concerns this article. Clearly, from the article information, it was published in 2016, and its title is "A new turtle taxon (Podocnemidoidea, Bothremydidae) reveals the oldest known dispersal event of the crown Pleurodira from Gondwana to Laurasia." Zoobank, for example, cites it with the 2016 date and describes the new species as "Algorachelus peregrinus Pérez-García, 2016."

But several others, including Pérez-García himself in 2020, cite this paper with a 2017 date: "Pérez-García, A. (2017b). A new turtle taxon (Podocnemidoidea, Bothremydidae) reveals the oldest known dispersal event of the crown Pleurodira from Gondwana to Laurasia. Journal of Systematic Palaeontology, 15, 709–731."

Why are both dates used, and which should I use when citing it in Wikipedia articles? HouseOfChange (talk) 18:12, 2 December 2021 (UTC)[reply]

The page says the paper was published online 28 Sep 2016, but if you look at the top right it was printed in volume 15 of the journal, which was for 2017. A paper can be published online almost immediately after it was accepted whereas printing it requires quite a bit of time. I would always cite the printed version with the cover date of the journal issue, in this case 2017. --Wrongfilter (talk) 18:28, 2 December 2021 (UTC)[reply]

... in case a Malthusian extinction should ever eliminate all digital archives, but the rampaging horde chooses not to burn the vaults full of paper print zoology journals? I wonder, realistically, which archival-format will last longer...

Wikipedia:Manual of Style links to citation style, which advises: "say where you read it." Unless you actually referenced a print copy of the 2017 publication, you ought to cite the digital copy, and its digital publication date, I think. Without independent verification, can you be sure that the printed publication is really the same article, as opposed to a "pretty similar one" with a "pretty similar title"? Nimur (talk) 20:15, 2 December 2021 (UTC)[reply]

If it's the web site of a respectable journal, if a pdf version of the paper is available, if it includes the full journal reference with volume number, page number or article id and publication year, then in all likelihood that is the definitive version. If it isn't then something is very wrong. In this case you can download the citation, you'll find that it gives 2017. And no, I don't cite anything that I haven't seen. --Wrongfilter (talk) 22:13, 2 December 2021 (UTC)[reply]

This is a thorny issue: have a look here. The data of publication is particularly important for the formal descriptions of new species, because the first published name has priority and because the full name of the species includes the date of publication. For old works, the critical issue is to try to establish when the work was actually sent out to libraries (rather than printed), hence the importance of library stamps on the covers of old journals that establish when that issue arrived. For modern journals published online and then printed it is critical to establish whether online-first versions are the version of record or if they may later be altered in non-trivial ways (i.e. not just a change of page numbering). "Version of record" is better explained here than in the Wikipedia article. Jmchutchinson (talk) 21:46, 2 December 2021 (UTC)[reply]

December 3

SARS‑CoV‑2 original strain name

Reading about the SARS‑CoV‑2 variants, a thought occurred to me; is there a name for the original strain of SARS‑CoV‑2, eg. "SARS‑CoV‑2 wild-type" or "SARS‑CoV‑2 original" or something like that? Or is its name just "SARS‑CoV‑2", without any qualifiers? There are some older designators, like SARS‑CoV‑2 strain G and SARS‑CoV‑2 strain L; are these differences regarded as being on the same level as the Greek-lettered variants, or as just minor differences within a single variant? The Anome (talk) 14:11, 3 December 2021 (UTC)[reply]

The article titled Variants of SARS-CoV-2 contains all the information you seek. As is stated in the "Overview" section, the ancestral strain was labeled "S" or "A" (by Chinese and Western researchers respectively) and the dominant derived strain from that was labeled "L" or "B" respectively by the same researchers. From the "B" type, we get the variant class "B.1" that produced most (but not all) of the WHO variants of concern. According to the section "Reference Sequence" notes that because there is not a clear "patient zero", it is impossible to identify and isolate the exact oldest variant, but that section gives several candidates, including one called "Wuhan-1", several others only identified by data base serial numbers. The greek letter system is ONLY used for particular "variants of concern", not all strains (there are thousands of identifiable strains of SARS-CoV-2) similar to how not all weather events get names, only those that reach certain thresholds. --Jayron 32 14:27, 3 December 2021 (UTC) Ed: I have amended my answer per below. --Jayron 32 15:18, 3 December 2021 (UTC)[reply]

All tropical storms get named, tropical storms that don't meet the criteria are not tropical storms but tropical depressions 1 through 89 (89 is unreachable) or tropical disturbances (either called invest 90L to 99L odometer-style (L if atLantic, A if Arabian, B if Bengal, C if CPac, E if EPac etc) or nothing at all). Sagittarian Milky Way (talk) 15:00, 3 December 2021 (UTC)[reply]

You forgot to say "well, axully..." Yes, thank you. You are correct. I have amended my answer. --Jayron 32 15:18, 3 December 2021 (UTC)[reply]

AFAIK there's no current variant of concern which is not from B.1. The gamma variant is labelled P.1 but only because of too many levels of varients as our article explains. Nil Einne (talk) 20:11, 4 December 2021 (UTC)[reply]

With rona it's too low by 1 and too late to fix (alpha should be beta, ixnay the germ with no name), with others it's too high by 1 and too late to fix (UXCIII is naked uranium, exoplanet letters always skip a, an octave is only seven notes, centuries would be normal if one 8th century book had AD 0) Sagittarian Milky Way (talk) 16:35, 3 December 2021 (UTC)[reply]

how long would an aqueous solution of imidacloprid last under visible light from a household LED bulb?

I’ve purchased Temprid Fx (containing imidacloprid concentrate plus a pyrethroid as part of a multi-prong effort against a bad domestic infestation by roaches in my NYC apartment. (I’m concerned about pyrethroid resistance so I got Temprid Fx knowing it contains a neonicotinoid. If I dilute the concentrate as directed and put it in a pump sprayer (it’s not exactly clear but it’s weakly opaque / whitish translucent) and left the sprayer it in my kitchen exposed to light for a few hours, how long (what order of magnitude of time) would it take for substantial amounts of the imidacloprid to degrade ? Yanping Nora Soong (talk) 16:27, 3 December 2021 (UTC)[reply]

According to our article, it has a half-life of 39 days on the surface of soil. I would expect something on the same order-of-magnitude in your kitchen. A few hours should not be enough to degrade it noticeably. --Jayron 32 17:10, 3 December 2021 (UTC)[reply]

The literature says it degrades rapidly in water when exposed to light via photolysis (UV). [2] In general, this seems to involve UV-wavelength light (e.g. half-life of 4 hours irradiated at 290 nm). How could I predict its half-life under visible light in aqueous solution? Could I predict it from the HOMO-LUMO gap? Yanping Nora Soong (talk) 15:11, 5 December 2021 (UTC)[reply]

December 5

Polymers and viruses classifications.

Weird, I been waiting almost 24 hours for SCSBot to add Dec. 4. So polymers have like a 3 by 2 classification. Polymers can be thermplastics, thermosets, and somewhat overlap elastomers. Polymers can also be amorphous or crystalline. However, elastomers are amorphous-only. But I'd like some crystalline examples.

Amorphous thermoplastics: Glue.

Amorphous thermosets: epoxy resins, polyurethanes.

Amorphous-elastomers: rubber bands, tires, and contact lens.

But what are crystalline examples, for thermoplastics and thermosets? The only 1 I have is glass. But is that a thermoplastic or thermoset? Elastomers can also sometimes be a thermoplastic or thermoset. Thermoplastics I believe have no cross-linking, thermosets high-cross linking, and elastomers low-cross linking.

I'm also looking for a categorical classification for viruses. The only 1 I can think of is enveloped viruses vs. non-enveloped viruses. Are there any others? Thanks. 67.165.185.178 (talk) 00:57, 5 December 2021 (UTC).[reply]

Virus classification Sagittarian Milky Way (talk) 01:50, 5 December 2021 (UTC)[reply]

Not a chemist, but since nobody else is replying, I'll mention that I looked at the articles liquid crystals, kevlar and spider silk, which sound to my naive mind like possible examples of crystalline polymers. The article on glass begins "Glass is a non-crystalline ...", which throws me off, but I don't want to tell you you're wrong, since words can have two meanings. Card Zero (talk) 16:29, 5 December 2021 (UTC)[reply]

Bird rabies?

Are birds susceptible to rabies (or any other transmissible neurological disease which causes aggression)? If so, can they transmit it to other birds and/or to people? (No, I have NOT been bitten by a bird -- I've watched a film where lots of people were!) 2601:646:8A81:6070:E03D:3B7A:ECA5:DA02 (talk) 06:28, 5 December 2021 (UTC)[reply]

From our article on rabies transmission: "Birds were first artificially infected with rabies in 1884; however, infected birds are largely, if not wholly, asymptomatic, and recover." Source. For this to occur naturally, a bird would have to either be bitten by or eat a rabid mammal first; in many cases of the former I suspect the bird would die from the wound before any viral CNS involvement (I'm guessing this is also why rabies in small terrestrial mammals is virtually never found). As for the latter, antibodies to the virus have been recorded in predatory and scavenger birds, but they seem to be clinically asymptomatic.

Neuroinflammation and/or neurodegeneration from any cause is capable of producing behavioral changes, including aggression, but these can vary significantly between individuals. Even rabies has multiple disparate outward presentations. The same is true for BSE and sad horse disease. So a particular disease would have to have a pretty specific mechanism to produce consistent behavioral results. I did find some reports of Mycoplasma gallisepticum infection decreasing aggression in male finches, but then this illness also causes lethargy so it's more likely these sick birds just didn't have the energy to get in fights. My brief search didn't return anything else documenting a neurological infection inducing aggression in birds. JoelleJay (talk) 08:11, 5 December 2021 (UTC)[reply]

If you've only seen the movie and not read the article you may not be aware that The Birds was inspired by real life events. The real life birds went crazy due to algae poisoning, though, which is not transmissible, and they didn't organize themselves into planned attacks like in the movie. Matt Deres (talk) 15:20, 5 December 2021 (UTC)[reply]

There are several behavior-altering parasites with birds as hosts: however, they all alter the behavior of the birds' prey rather than that of the bird itself. The default bird activity of flying around eating stuff, and depositing it again in random places, serves parasites very well without the need for any alterations such as aggression. The evolutionary pressure might be different if birds were large and durable, had teeth and were bitey. Rabid pterosaurs are a plausible concept. One might also wonder about ostriches, but I think they tend to kick rather than peck, which removes the transmission vector through saliva. Card Zero (talk) 16:09, 5 December 2021 (UTC)[reply]

Russian nuclear missiles

In the early 1960s, were the warheads on Russian sub-launched nuclear missiles single-point safe? In other words, might an on-board reactor explosion have set off the warheads and caused a full-scale nuclear explosion, as Captain Vostrikov claimed? 2601:646:8A81:6070:E03D:3B7A:ECA5:DA02 (talk) 06:43, 5 December 2021 (UTC)[reply]

I think the design of the nuclear warheads that were the payload of the R-13 missiles aboard the K-19 is still a guarded secret. No nuclear reactor has ever "exploded", other than steam explosions; the worst accidents have been meltdowns. A nuclear explosion close to a fission weapon is – I think – more likely to destroy it before it can go off than to set it off, regardless of its design. In either case, the resulting contamination is disastrous. --Lambiam 08:55, 5 December 2021 (UTC)[reply]

BTW, the captain at the time of the incident was Nikolai Vladimirovich Zateyev. "Captain Alexei Vostrikov" is a pseudonym of Indiana Jones, an infamous archaeologist who claims to have made the Kessel Run in less than twelve parsecs – thereby establishing a lack of scientific credentials. --Lambiam 09:03, 5 December 2021 (UTC)[reply]

What I meant is a steam and/or hydrogen explosion in the reactor (like at Chernobyl) setting off the warheads. 2601:646:8A81:6070:E03D:3B7A:ECA5:DA02 (talk) 10:22, 5 December 2021 (UTC)[reply]

So where exactly DO we go one and all?

In a sailing vessel with a hybrid (both square and fore-and-aft) sail plan (such as a brigantine), if a white squall (or any other squall, for that matter) approaches from abeam without warning, which way should the helmsman turn her if her square sails are set -- upwind or downwind? How about if only the fore-and-aft sails are set? 2601:646:8A81:6070:E03D:3B7A:ECA5:DA02 (talk) 06:54, 5 December 2021 (UTC)[reply]

I think the general advice is to turn into the wind and confront any approaching high waves from the bow, but immediate reefing or even dropping the sails, especially those more to the fore, is also important to avoid the vessel capsizing or a mast breaking; the direction of the wind may vary abruptly during a squall. --Lambiam 08:25, 5 December 2021 (UTC)[reply]

Unlike the days of wooden ships, it is rarely feasible to send down steel topmasts and yards to reduce overpowering windage, nor to cut away a mast to relieve a ship on its beam ends. The master must rely on situational awareness of a thousand factors to avoid or find a way through mayhem... The practice in square-rigged ships encountering squalls is to bear away, ensuring that the load remains abaft the rig. Sheeting of fore-and-aft sails or the setting of an autopilot can frustrate this... From Sailing ships: a catalogue of disasters. Alansplodge (talk) 15:31, 5 December 2021 (UTC)[reply]

Land between two tributaries/rivers

Overall, the land drained by a river is called a drainage basin or watershed (or a bunch of other names listed there), but is there a more specific name for the localized space between two tributaries? For example, if a city was built at the place where two tributaries met, how would we describe its placement? It feels like there would be a name for that. When I search online for land between two rivers it leads me to Mesopotamia which is cool, but not really what I'm after. Matt Deres (talk) 15:27, 5 December 2021 (UTC)[reply]

The place where two rivers join is called the confluence. Cities built there are often described as "located at the confluence of the ___________ and _________." See: https://ludwig.guru/s/located+at+the+confluence --Khajidha (talk) 15:32, 5 December 2021 (UTC)[reply]

And our confluence article. Alansplodge (talk) 15:35, 5 December 2021 (UTC)[reply]

Aha! I knew there was a word; it just wouldn't come to mind. Thank you both! Matt Deres (talk) 16:30, 5 December 2021 (UTC)[reply]

But it's only part of what you asked for. Is there a word for the zone between two tributaries? --184.144.99.241 (talk) 22:27, 5 December 2021 (UTC)[reply]

I also want to know if there's a word for this except any combination of rivers, seas etc, not just tributaries. Sagittarian Milky Way (talk) 22:41, 5 December 2021 (UTC)[reply]

Impact of tobacco toxins on plant itself

Cigarette#Health_effects says there are "many toxic chemicals in the natural tobacco leaf" that are already there before smoking. Why they don't harm or damage plant's own DNA? 212.180.235.46 (talk) 16:57, 5 December 2021 (UTC)[reply]

How do you know they don't? ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:33, 5 December 2021 (UTC)[reply]

Many plants have toxic chemicals that act as insecticides and/or fungicides. Tobacco used to be (and still can be) used as an insecticide: "Tobacco and its evil cousin nicotine are good as a pesticide". American Chemical Society. -- 2603:6081:1C00:1187:C0D8:D7A:7996:A83B (talk) 20:48, 5 December 2021 (UTC)[reply]

Would non-binary mammals be more efficient?

If everything had a wang and a womb and reluctance to being inseminated was the sexual minority instead of the other way around then the gene pool would be pregnant almost 24/7. Though if it were possible for that to be good enough to outcompete what we have now (?) and also to arise from random mutations in the first place (??) then sex may become more and more flatworm-like and evil over time with less of the gene pool pregnant at any given time. Sagittarian Milky Way (talk) 17:58, 5 December 2021 (UTC)[reply]

It would help if "efficient" was clarified for this context. However, there are reasons why flatworms do not rule the planet, or even fill all that many niches that other organisms haven't evolved to better fill. In terms of mammals doing this, I'd suggest that it would be inefficient from a resource perspective. Remember that any structures and organs within a given organism require both raw materials and energy (LOTS of energy) to produce, grow, and maintain. Let's just say that 50% of the time, half of those reproductive organs end up not being used during reproduction... that's an enormous waste of resources and energy. At least among chordates (as far as I am aware), hermaphroditism is very much the exception, not the rule, and usually only occurs under extreme stresses (such as an isolated population that almost entirely lacks one gender, and so needs to spontaneously get some of that gender or reproductive capability or die off). Additionally, what you are calling "reluctance to being inseminated" would be more properly called sexual selection, which is a tremendous driving force of natural selection and fitness of future generations. Given that, I doubt that removing sexual selection would be any more "efficient" at anything other than producing a ton of offspring, but those offspring have just lost benefit to one of the major factors in determining fitness. That's not very efficient, at least not in my book. Lastly, what do you mean by "evil" in this context? I have absolutely not idea. --OuroborosCobra (talk) 18:35, 5 December 2021 (UTC)[reply]

Perhaps the drawbacks of each organism having a half-system on each side would overwhelm the ability to outreproduce then. At least for "complex" or locomoting life. Well if everything was enough like the flatworms that make the news then Earth would be like a planet of sex predators and there may not be enough inter-individual cooperation for technology to ever get very high, though what does and doesn't seem evil is fuzzy and inconsistent within one human much less one culture. Spiders and parasitic wasps seem evil to me but flesh-eating bacteriums and Guinea worms don't have enough anthropomorphicizability-to-cruelty ratio. If I saw flatworms trying to stab the others' skin with their penis I wouldn't stomp them but if I saw a spider being as unoffensive as possible I stomp even though another will quickly take it's place but if it's too inconvenient I'm not bugged that bugs will be eaten alive for my convenience. Sagittarian Milky Way (talk) 22:05, 5 December 2021 (UTC)[reply]

A tyrannosaurus by any other name

Ever since their discovery and modern interpretation, dinosaurs and other prehistoric animals have captured the popular imagination and, since they were not given "everyday" names, the public knows them solely by their genus names with one exception - the T. rex. Is there a specific (pun not intended) reason why it's the only prehistoric animal for which people know the species name? Or is it random happenstance? I'd wager almost nobody outside of paleontology could even hazard a guess of any other dino's species name, yet every 8-year-old in the world knows rex. I'd even wager that, outside of H. sapiens, Tyrannosaurus rex is likely the best-known species binomial, period. Is there a reason why? Matt Deres (talk) 20:49, 5 December 2021 (UTC)[reply]

Probably just happenstance. The meanings of the two parts of the binomial add up to "king of the tyrant lizards", and that has a sort of poetic feel that resonates, but it would not guarantee the widespread knowledge. Boa constrictor might be even more well known. Possibly even more well known than Homo sapiens, but most people may not realize that the "common name" there actually is the scientific name. --Khajidha (talk) 20:58, 5 December 2021 (UTC)[reply]

The Western gorilla is Gorilla gorilla, but that's not quite what you were asking about.--Khajidha (talk) 21:01, 5 December 2021 (UTC)[reply]

I'll see your Gorilla gorilla and raise you Bison bison bison. Card Zero (talk) 02:37, 6 December 2021 (UTC)[reply]

There's also a gorillier gorilla (Gorilla gorilla gorilla). Of tribe gorillini. Sagittarian Milky Way (talk) 03:13, 6 December 2021 (UTC)[reply]

The expression E. coli is pretty well known, but the full genus-name Escherichia, not so much. --184.144.99.241 (talk) 22:30, 5 December 2021 (UTC)[reply]

Heck, I deal with cultures of E. coli at work, and still keep misspelling it as"Escherischia". --Khajidha (talk) 23:56, 5 December 2021 (UTC)[reply]

So did I when I first typed my comment. I was saved because no one's made that misspelling a link. --184.144.99.241 (talk) 04:22, 6 December 2021 (UTC)[reply]

This question reminds me of the "Did You Know" segment from the main page on April 1 2010. Wikipedia:Recent_additions/2010/April#1_April_2010

ApLundell (talk) 02:45, 6 December 2021 (UTC)[reply]

The single-syllable specific name makes it catchy and easy to remember. How many others are there? Crex crex, Lynx lynx. Not many. Card Zero (talk) 03:14, 6 December 2021 (UTC)[reply]

Aha ha. Sagittarian Milky Way (talk) 03:23, 6 December 2021 (UTC)[reply]

Nice, and there's the list. That T.L. Erwin's taxonomy is out of control. Agra dax, Agra max, Agra nex, Agra nox... Card Zero (talk) 03:40, 6 December 2021 (UTC)[reply]

December 6

Protons and neutrons in Atomic nucleus

Atomic nucleus has diagrams of nuclei with the protons and neutrons as spheres. For a given isotope with a large number of nucleons (e.g. lead-208), do the protons and neutrons in the nucleus always have the same arrangement?

(Or are those images an oversimplification?) Bubba73 ^{You talkin' to me?} 03:33, 6 December 2021 (UTC)[reply]

Technetium 99m is a different arrangement and half-life and is ellipsoidal I think. There are many such nuclear isomers, some are numbered things like m2 cause an isotope has more than one "imperfect form". Nuclei also have nuclear shells. Sagittarian Milky Way (talk) 03:53, 6 December 2021 (UTC)[reply]

There is a section for Atomic nucleus#Composition and shape that has some details and refs (and the surprising detail that some of the nuclear particles might exist at the exact same location as each other). Searching for "shape isomer" in the the nuclear isomer article finds some additional relevant info. The Nilsson model is some complex math, but it makes the point that some observed nuclear properties contradict a perfect spherical shape. DMacks (talk) 04:16, 6 December 2021 (UTC)[reply]