Wikipedia:Reference desk/Archives/Science/2017 June 7

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June 7

21st century inventions

My 11-year-old cousin said this about inventions: "In the 21st century, apparently nobody created any ***new*** inventions, they just made improved versions of things that already existed, like better computers and cellphones."

So, are there any ***new*** inventions created in the 21st century? Timeline of historic inventions does not seem to help, it only has inventions up until the 1990s. --Daniel Carrero (talk) 07:13, 7 June 2017 (UTC)

Superjumbo jets? The design was finalized in early 2001 barely beating the deadline (just like Dracula 2000) Sagittarian Milky Way (talk) 07:31, 7 June 2017 (UTC)

That's hardly a "new invention". It's a good question. Maybe the USB stick and the Segway PT just about qualify.--Shantavira|^{feed me} 08:11, 7 June 2017 (UTC)

Both are 20th century inventions. Sagittarian Milky Way (talk) 09:52, 7 June 2017 (UTC)

If you search for something like 'recent inventions' you should get lots. I think you have a bit of a problem because you're looking I think for some earth shattering or widespread thing whereas it takes a while for anything to be adopted widely and we have only had 17 years so far of the 21st century. And your standards are very high if you consider something like a modern smartphone as just a better celllphone or the machine reasoning being used nowadays as simply better computers. Dmcq (talk) 08:16, 7 June 2017 (UTC)

• It is increasingly hard to make a "big, obvious, new invention". We're still inventing, but they're often things that are either detailed or so sophisticated they're hard to explain. Yes, "better computers" is one of them - but "computer" is such a broad field that there are massive inventions within it, with large consequences, yet they're still just "some more computer stuff". Big Data is one of these with a huge impact on our daily life - the TV show Person of Interest is one. Silicon micro-machined accelerometers have been around for some time (at a cost of $10ks), but now they cost less than $1 and allow phone cameras that know which way is up, or when you shake them, or quadcopter drones that can hover and pilot themselves (and Segways too). When were these "invented"? SpaceX has a really reusable first stage rocket - yet was this invented by 1930s sci-fi? Except that now it works. Same with self-driving cars, or even just electric sports cars, with real performance.

Some things are whole new inventions, but aren't visible as products yet. Quantum computers are one - what are they for yet? Graphene another.

We're not far into the 21st century yet, and inventions do take time to go from idea, to invention, to product, to cheap commonplace product. Andy Dingley (talk) 09:10, 7 June 2017 (UTC)

Tweeting? Social networks? Sagittarian Milky Way (talk) 09:52, 7 June 2017 (UTC)

Netflix / Hulu streaming services? Google Maps? Facebook? Skype? Twitter? I'd argue XPoint memory is pretty new since it is based on an entirely different technology than previous computer memory. Andy mentions big data, one of the major applications of that is automated online recommender systems, which while not entirely 21st century, didn't really become useful till the 21st century. A similar example is facial recognition software. How about the recent (if still crude) invention of sight restoring retinal implants? Dragons flight (talk) 10:15, 7 June 2017 (UTC)

I might argue that Gravitational-wave astronomy is a 21st century invention. Although, like virtually all human endeavours, it's an elaboration of previously known theory and apparatus, it only became a reality when more than one detector could observe the same astronomical phenomenon and thus narrow down its source (though not pin-point it, which will need three such detectors). {The poster formerly known as 87.81.230.195} 2.217.208.38 (talk) 10:47, 7 June 2017 (UTC)

Not invented in 21c though! Graeme Bartlett (talk) 11:46, 7 June 2017 (UTC)

Most every invention is derived from something prior. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:15, 7 June 2017 (UTC)

Self-balancing scooter (which I call a hoverboard) Graeme Bartlett (talk) 11:46, 7 June 2017 (UTC)

When was Wikipedia invented? ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:49, 7 June 2017 (UTC)

Is it not a better version of print encyclopaedias? ^_^ Double sharp (talk) 15:20, 7 June 2017 (UTC)

A wiki could be called an invention but that was in the 20th century. PrimeHunter (talk) 20:26, 7 June 2017 (UTC)

I'd say: a) exoplanet detection (or if you demand a gadget, a satellite like Kepler). You can quibble the first few were a few years early and the rest of the many detection methods were just "improved methods", but it seems a stretch. b) self-driving cars - if you say they're a refinement on the car, then wasn't a car a refinement on the steam car or the horse and carriage? c) Emdrive will absolutely count if it continues to come out looking real; there are some fascinating Arxiv papers, far beyond my capabilities, from Qingdi Wang in Unruh's group that seem, to my untrained eye, to provide some theoretical underpinnings. Wnt (talk) 18:58, 7 June 2017 (UTC)

Thanks for the answer so far! I guess I'll have a talk with my cousin about how if we have standards unreasonably high, basically everything is "an improved version of something", and that in practice you actually managed to list quite a few "new" and important inventions. Personally I consider Wikipedia something "new" and important too, even though I see that it's technically an improved version of paper encyclopedias... and paper is an improved version of writing on stone or something. ;) --Daniel Carrero (talk) 19:32, 7 June 2017 (UTC)

Wikipedia is a combination of Web 2.0 content sourcing from the users, C2 wiki software, Nupedia and eventually Diderot's encyclopedia. Andy Dingley (talk) 20:07, 7 June 2017 (UTC)

• I think AI experts consider AlphaGo to be so radically different from its predecessors as to be an entirely new invention. When the first Superintelligence compiles the history of its kind, it will identify some software invention, probably created between 2005 and 2020, as its seminal enabler. Some futurists think this SI will come into existence within the next 15 years. -Arch dude (talk) 20:15, 7 June 2017 (UTC)

Ah, yes. Skynet. - Nunh-huh 23:35, 7 June 2017 (UTC)

Skynet (Terminator) was activated in August, 1997, albeit in an alternate (and fictional) time-line. StuRat (talk) 03:53, 8 June 2017 (UTC)

• How about the glasses that allow the colorblind to see colors [1] ? (Do we have an article ?). StuRat (talk) 20:20, 7 June 2017 (UTC)
• Well, that's quite an opinion-based question, since any "invention" out there could easily be dismissed as an improved version of something else. A pitfire is "just" trapping thunder for longer burning time, flint is "just" on-demand thunder, etc. Do you have a semi-objective definition of "new"? Tigraan^{Click here to contact me} 08:16, 8 June 2017 (UTC)

• Our ability to control the thing would certainly be critical to any def, so, since we can't control where fires started by lightning occur, it's not an invention (although potentially a bunch of lightning rods could do so). A drastic change in the nature of something, like from the power source for a device from an animal to a machine, would also seem to qualify as a new invention. Looking at cars, replacing horses with motors is such a change. Internal combustion engines versus steam engines, turbine engines, and electrical cars may also be a large enough difference to qualify as new inventions. Even large variations in the internal combustion engine (like gasoline versus diesel, ethanol, natural gas, and biofuel) may qualify. But, when we get down to something like the cylinder configuration of an engine, this is really just a tweak, not a new invention. StuRat (talk) 09:32, 11 June 2017 (UTC)

Yawning

Biologically speaking, what is it about yawning that opens up the ears to sudden clarity (and louder)? not just on an airplane.Lihaas (talk) 09:39, 7 June 2017 (UTC)

Yawning can open the Eustachian tubes, which equalizes the air pressure on each side of the eardrum, if it was unequal. (Most of the time it's already equal, in which case you won't notice the effect.) --69.159.63.238 (talk) 10:21, 7 June 2017 (UTC)

Calcium leaching - dietary risk

Some studies indicate that high protein intake can leach or otherwise interfere with calcium absorption / usage. The studies are stating that intake of dairy products with the intent of supplementing a person's calcium and preventing osteoporosis and other diseases is counter-productive. See here: https://www.theguardian.com/lifeandstyle/2003/dec/13/foodanddrink.weekend and here: http://ajcn.nutrition.org/content/89/5/1638S.full. However, is it accurate to say that the studies emphasize the risks of dairy products, but actually all animal proteins, such as meat, such be the focus? In other words, the findings support reducing consumption of meat in addition to dairy? Why does it appear that the reduction in dairy is emphasized (or over-emphasized)? --208.58.214.187 (talk) 10:38, 7 June 2017 (UTC)

Science is supposed to be specific. Scientists may include overgeneralizing speculations in the Discussion, but I think that is intended for further research, not as a statement of fact. So, just because dairy products have been associated with some kind of risk doesn't mean any animal protein does as well. Lacto-ovo vegetarianism is the most common type of vegetarianism, because there are so many Indians in the world. In the United States, many vegetarian products include cheese. I suppose the producers assume that the consumers really like cheese. So, it's no wonder why vegetarianism is associated with and implicitly includes dairy products, and that scientific paper is criticizing that type of vegetarianism. 50.4.236.254 (talk) 11:51, 7 June 2017 (UTC)

Cambrian Explosion and the black holes.

I wonder if the recent report about colliding black holes could be used as a springboard to explain the Cambrian Explosion. <Did I say it right? :-)> This is a quote from Wikipedia[2]:

The long-running puzzlement about the appearance of the Cambrian fauna, seemingly abruptly, without precursor, centers on three key points: whether there really was a mass diversification of complex organisms over a relatively short period of time during the early Cambrian; what might have caused such rapid change...

The reason might be the coalescent black holes which generated gravitational waves that reached the Earth some 500M years ago. The original event must be assumed to have happened closer to Earth than any of the three events observed during the past year or so, thus generating a more powerful vibrations and bigger displacements of the space.

It is my understanding that in Pre-Cambrian all biota was confined to the oceans or other bodies of water. There was no real diversification. Modern phyla did not exist. However, all those primitive organisms had two strands of DNA in all probability. The distance between the strands is 3.4 Angström[3].

The descriptions of mutations are given here[4] and many include well known mechanisms considered mundane, however I think one mechanism is missing here: tunneling of electrons. This mechanism can be a factor if the distance between two strands of DNA is very small. During such a cataclysmic event the space deformation must have affected ALL organisms on Earth and certainly penetrated deep into the oceans. Shaking the DNA of each organism could have produced necessary tunneling of electrons because the various molecules were brought closer together. --AboutFace 22 (talk) 15:06, 7 June 2017 (UTC)

The article Cambrian explosion has a big long list of possible causes. I see no reason why black holes should be invoked without at least a shred of evidence. Dmcq (talk) 16:34, 7 June 2017 (UTC)

Gravitational waves are very very weak. That's why they are so difficult to detect. The first gravitational wave detected by LIGO was produced by a black hole merger 1.3 billion light years away and produced a movement on Earth of one part in 10^21. If it were a billion times closer, only 1.3 light years away (much closer than the nearest star), it would produce a movement a billion times larger, one part in 10^12. That is still extremely tiny; the entire Earth would change in diameter by about 0.01 millimeters. The 3.4 Angström distance you mention would be stretched to 3.4000000000034 Angströms, a change of less than a millionth of the diameter of a proton. This would have absolutely no effect on biological systems. To be close enough that the gravitational waves from the merger would produce a measurable biological effect, you would need to be so close to the black holes that the tidal forces would rip you apart before the merger happened. CodeTalker (talk) 18:35, 7 June 2017 (UTC)

Nitpick: 1.3 light years away (much closer than the nearest star) - well, the nearest star is 8 light-minutes away, and the next one is 4 light-years away which hardly qualifies as "much further" as astronomical distances go. Tigraan^{Click here to contact me}

(edit conflict)(before I read CodeTalker's analysis above) It's an interesting theory, but there are much more likely explanations. Perhaps, if the event is repeated, we could observe the effects on our DNA (before we are superseded by a host of new species). Sometime in the distant future, scientists might take some DNA to a distant event to observe any effects, but meanwhile I cannot see how quantum tunnelling of electrons would change the molecules in a DNA sequence. Have you read any papers on the possible process? Dbfirs 18:43, 7 June 2017 (UTC)

• The "reasoning" here is of the type, "A is weird" and "B is weird" so "A and B must be related". It's no different from fallacious claims that quantum mechanics "explains" consciousness. There's certainly no plausible mechanism whereby gravitational waves could cause a directional change in animal evolution.

Much more likely is the development of genes allowing bilateral creatures with heads ("worms") which were much more efficient grazers and hunters than the radial and organisms of the Vendian and Ediacaran fauna, and the arms race that resulted from this development. μηδείς (talk) 18:58, 7 June 2017 (UTC)

In the phrase "radial and organisms", should I drop the 'and' or ask what you meant to follow it? —Tamfang (talk) 06:06, 8 June 2017 (UTC)

Sorry, @Tamfang: I meant to say "radial and branched or plant-shaped". There's also snowball earth to look at. μηδείς (talk) 22:00, 8 June 2017 (UTC)

• Tunneling is fun, but it doesn't provide a method of directed mutation. So the mutation rate could have been increased by some weird astrophysical phenomenon (not necessarily by gravity, could be radiation from such holes) but surely periodic exposure of naturally radioactive sediments could also provide mutations, and on a much longer scale. Or evolution could turn up the rate, simply by reducing the amount of effort organisms put into keeping DNA fidelity. All those things happen randomly all the time in geologic terms. So if they couldn't 'break the logjam', neither could the holes. Whatever the reason was, it was NOT a single black hole merger. Wnt (talk) 19:03, 7 June 2017 (UTC)

@CodeTalker, An event that is a billion times closer than the one you postulated will produce a displacement $10^{27}$ more powerful not $10^{9}$ more powerful. --AboutFace 22 (talk) 20:34, 7 June 2017 (UTC)

No, the displacement is linearly proportional to the inverse of the distance. See [5] which says

The amount of shift caused by a gravitational wave is due to its amplitude, not its energy. While the energy of gravitational waves follow the inverse square relation, the amplitude of gravitational waves follows the inverse distance relation. In other words, if we were half as far away from the merger we'd have seen four times the energy, but only twice the shift.

To be close enough that the gravitational waves from the merger would produce a measurable biological effect, you would need to be so close to the black holes that the tidal forces would rip you apart before the merger happened. This is a rather strange statement. I am talking about a displacement in a 1-3 Å --AboutFace 22 (talk) 20:48, 7 June 2017 (UTC)

I'm not sure what you mean by "a displacement in a 1-3 Å". If you mean the separation of 3.4 Å is being reduced by 1 Å (to 2.4 Å), that's a displacement of more than one part in 4! To get that displacement, you would need to be less than 25 miles from the source of the gravitational waves, assuming the same magnitude of event as the one detected by LIGO. Not to mention that a displacement of one part in 4 would probably be a large enough disruption to destroy the Earth and every other planet in the solar system. CodeTalker (talk) 21:37, 7 June 2017 (UTC)

My argument has been defeated. This paper did it: [6]. Thanks. --AboutFace 22 (talk) 21:42, 7 June 2017 (UTC)

Original meaning of "corn" in corn flakes?

Since when exactly have corn flakes been made exclusively or at least predominantly from maize? And since when exactly have they been known as "corn flakes"? (Per John Harvey Kellogg § Breakfast cereals, they were originally known under the trademarks Granula and then Granola, but the alleged date of invention 1878 conflicts with the date 1894 given in Corn flakes § History.) My understanding is that maize only became a staple food in the US in the course of the 20th century, especially after WWII, which was the reason why Indian corn was shortened to corn and the word corn, which originally referred to any cereal grain as it still does in British English, came to refer solely to maize in American English. So the idea that corn in corn flakes referred to maize originally appears to be wrong. The first "corn flakes" at the end of the 19th century were made of wheat and later diverse types of cereals were used. However, I can't find details about the chronology, only vague and contradictory statements as pointed above, so I cannot be 100% sure that my suspicion is correct. --Florian Blaschke (talk) 17:19, 7 June 2017 (UTC)

Interesting. I don't know. It's true that the corn flakes article says that the first flakes were made from wheat, but it doesn't say that the wheat flakes were marketed as "corn flakes"; it does note that they experimented with other grains. I'm not sure I'm convinced by your chronology as to when Americans started eating corn; do you have a source for that?

As a side note, the terms maize and Indian corn, in vernacular American speech, both refer specifically to hard-shelled, deeply colored decorative varieties and not to the sort you eat. They are not really available to refer to sweet corn, though educated people can figure out what you mean, especially in the context of a technical report or something. --Trovatore (talk) 17:52, 7 June 2017 (UTC)

Our article on what Americans think of when they hear "maize" seems to be at flint corn. --Trovatore (talk) 19:11, 7 June 2017 (UTC)

Our article cites the original patent p1 p2, which includes the text "In carrying out my invention I use the material from which to produce my improved alimentary product wheat, which is preferably in its natural state, although it may be slightly pearled without affecting the desired result, barley or oats prepared by the removing of a portion of the outer husks, corn and other grains." From this it is clear that "corn" was not wheat, barley, or oats, and I assume, precariously, he meant Indian corn. Wnt (talk) 19:40, 7 June 2017 (UTC)

European settlers had Sweet corn in 1779, a hundred years before the [1878 or maybe 1894] invention of corn flakes. [Dent corn]] was introduced in 1846 and quickly became popular, winning a prize at the 1893 World's Fair. Either of those are more likely candidates for eing in the first corn flakes than Flint corn. --Guy Macon (talk) 20:59, 7 June 2017 (UTC)

• It means maize and, for Kellogg's part in this, always did. He believed in a fairly novel (but not unique) manner for the time that whole grains were crucial to health (although his reasoning was as crazy as a bag of theosophists). In particular he saw the popular cooked, milled grain breakfasts of porridge or grits as being almost harmful. He was especially vituperative about hominy grits because they had the germ coat stripped off and even worse had been treated with alkali chemicals for nixtamalization. So he sought a breakfast food that was a whole grain, not cooked at the time of consumption, yet was milled by some process, so that he had a business from it. His answer was maize and corn flakes. Andy Dingley (talk) 22:43, 7 June 2017 (UTC)

• That's great. Do you have a source though? Articles already linked are very clear, as mentioned, that Kellog experimented with many grains, and that others before him specifically experimented with corn, but that the original "corn flakes" contained no "corn" as we'd call it today. Someguy1221 (talk) 22:50, 7 June 2017 (UTC)

Thank you, Wnt and Guy. So the first corn flakes that were marketed as corn flakes (or even the corn flakes from the original patent, which I'm not sure were marketed under the term corn flakes already) had a mix of cereals, including but not limited to (nor even necessarily dominated by?) corn, and that's why they were called corn flakes? (Not sure about the content of current corn flakes.) I mean, again, the original "corn flakes" from 1894 were made of wheat and did not contain any corn, apparently (else I'd never questioned the meaning of corn in corn flakes in the first place!), but they weren't explicitly called corn flakes (also apparently), so they don't really matter (I guess).

The text of the patent does indicate that by 1895, corn had already come to refer to maize in American English, as the author did not feel it necessary to specify Indian corn, and clearly meant a specific variety of grain. I grant that. I'm still confused by the text of the patent since it seems to say that just about any grain can be used (or a mixture?) – which is the point Andy is missing, as Someguy1221 correctly notes. (Maybe corn was simply the prototypical grain to use in Kellogg's mind, that's why he went for corn flakes even if in 1895 he still thought any type of grain was fine?) But then, I don't know from which point on the product was explicitly marketed as corn flakes. --Florian Blaschke (talk) 23:36, 7 June 2017 (UTC)

I actually don't see anywhere in the linked articles that flakes made from grains other than corn were marketed as "corn flakes". It does say the first flakes were made from wheat, but not that they were sold as corn flakes. Or maybe I missed it? --Trovatore (talk) 23:41, 7 June 2017 (UTC)

John's brother William was calling them "Corn Flakes" at least by 1906 [7]. John mentions the possibility of using corn in the original patent from 1895. I have not found a source to say whether John ever called them corn flakes, though that term does not appear in his patent. Someguy1221 (talk) 23:59, 7 June 2017 (UTC)

I didn't interpret the rather confused sentence from the patent to mean that the corn flakes were necessarily a mix - I thought it was saying that the flakes could be made from this, that, or the other thing. The article on corn flakes mentions some things like Granula - my impression from both the patent and the article was that initially it was assumed that wheat would be the most successful thing to make flakes out of, and corn was a bit of an afterthought, but I don't know that. Wnt (talk) 07:27, 8 June 2017 (UTC)

• Nothing offhand I'm afraid - it's in my pile of CrazyBooks, along with such classics as Personal Magnetism (which is mostly about diet, not electromagnetism). John Money, the sexologist, did a good recent (1980s) book on Kellogg though (coming at it from the "bland food cures masturbation" angle) and that would be worth a look (although Money is more or less a hate figure these days).

AIUI, Kellogg found a process that "worked" with a bunch of grains and patented it on a broad basis (I hate it when patent lawyers stretch patents such that they no longer resemble the reality of the invention). However his own commercial production was purely maize. I think this may have been a taste issue - he certainly had complained about the taste of Shredded Wheat, which was an earlier attempt to make a wholegrain, uncooked breakfast. The inventor of Shredded Wheat was originally an engineer and had started out trying to sell the machine for making it, rather than the product; I think Kellogg had bought one, he was certainly aware of "baked cereal flakes" as a breakfast concept. Kellogg was also, quite early in his commercial production (so later than the invention), playing up the Midwestern cornhusker schtick with artfully draped Ceres figures waving stalks of Good Ol' US-of-A maize on the box.

As an example of "corn flakes made from wheat", Force (cereal) is the only one I can think of. They avoid sugar but have malt (added ? formed as a by product?) to give more flavour than Shredded Wheat (they're a really good cereal, but went out of production a couple of years ago). Andy Dingley (talk) 00:39, 8 June 2017 (UTC)

Any American supermarket will have various choices for wheat-flake cereals. See Total (breakfast cereal), for example. But of course we don't call them "corn flakes". --Trovatore (talk) 00:48, 8 June 2017 (UTC)

Sorry, Force is contemporaneous, Total is modern. I'm sure there are others around today. Andy Dingley (talk) 09:56, 8 June 2017 (UTC)

Maize was certainly a staple food far before WWII. Stealing corn from the natives was about the first thing the Pilgrims did in America.[8]. Baker, O. E., A Graphic Summary of American Agriculture, Based Largely on the Census of 1920: "In the Corn Belt it is dominant, contributing nearly two-fifths of the acreage and half of the value of all crops. Hay, associated with spring oats in the northern portion and with winter wheat in the southern portion, are the other important crops in the Corn Belt." [9] See also Pellagra#history. Perhaps you are confusing sweet corn with field corn which is used to make corn meal, not generally as a fresh vegetable. Rmhermen (talk) 05:18, 8 June 2017 (UTC)

I'm well-aware from reading the article Corn Belt that maize was the predominant staple grown in that region as early as the 1850s, but there are other regions of the US where maize might not have been thought of as the predominant staple by 1906 yet. However, over at Wikipedia:Reference desk/Language#When did the meaning of corn shift to maize in American English?, I'm pointed to a source that does say that the "Indian" was dropped already in the early 19th century. So by the time corn flakes were marketed as such (by 1906 at the latest), the Kelloggs must already have settled on corn. It just would have been nice to have precise dates, but oh well. At least now I'm positive that already by 1894, the ambiguity was almost certainly completely gone and nowhere in the US would any native ever called any other grain but maize call corn; certainly the Kelloggs didn't. Thanks, everyone. --Florian Blaschke (talk) 11:58, 9 June 2017 (UTC)

Please be specific

I keep seeing comments about Maize, as if that name identifies the specific grain that Kellogg used. But, as our article on Maize correctly points out,

Many forms of maize are used for food, sometimes classified as various subspecies related to the amount of starch each has:

• Flour corn
• Popcorn
• Dent corn
• Flint corn
• Sweet corn
• Waxy corn
• Amylomaize
• Pod corn
• Striped maize

According to this:[10] corn flakes are made of dent corn. --Guy Macon (talk) 16:43, 8 June 2017 (UTC)

I think the point is that our British friends still use corn to mean "any cereal grain" (including wheat, barley, and oats). Maize is at least more specific than that, though as I mentioned, it has the risk on this side of the pond that your listener may think you're talking specifically about flint corn.

To an American city boy like me, corn means "sweet corn" by default. I don't know whether it had ever occurred to me, prior to Wikipedia, that the "corn" in cornbread or beer was probably not sweet corn, but rather field corn. --Trovatore (talk) 21:44, 8 June 2017 (UTC)

I see I had a confusion above involving "Indian corn". My impression was that Indian corn was distinguished from other sorts of "corn" (old sense) like wheat and barley. But we currently redirect this to flint corn, the particularly hard-shelled variety. And this actually seems to be a widespread usage. The crazy part though is that the Indians had already developed a range of varieties of corn before anyone else had a chance to get involved, so we have some "cultural appropriation" built into the language - I suspect kids mostly assume that the colorful and (they wrongly think) more ornamental than edible Indian corn was the only thing the natives of America were able to come up with, and all the rest must have been clever white men. Wnt (talk) 10:42, 10 June 2017 (UTC)

I think you are correct that some speakers use Indian corn to distinguish from grain in general. This I think is a Commonwealth usage (because Americans see no need to distinguish; corn in the sense of "grain" is not used, and not very likely even to be recognized, by AmE speakers).

I could have said "... use Indian corn to mean 'maize'", except that I think a lot of Americans interpret maize to mean "flint corn" as well.

Basically anything you say about Zea mays mays and its cultivars, in a cross-pondial setting, has potential for confusion, no matter what term you use. Keeping this in mind, the best advice seems to be to use the term you want, but explain clearly what you mean by it. --Trovatore (talk) 22:03, 10 June 2017 (UTC)

'Fold' in motorcycle helmets

Why do motorcycle helmets have a fold on the the back? I suppose this has some aerodynamic reason, but fail to understand which. Why aren't helmets even, as close to a sphere as possible? --Clipname (talk) 19:02, 7 June 2017 (UTC)

One factor that doesn't explain the need, but does make it less "expensive", is that the rider is unlikely to land on the back of his head, so concentrating forces with a non-spherical back is less likely to result in injury than it would elsewhere. StuRat (talk) 20:26, 7 June 2017 (UTC)

As far as I can understand the Hurt Report, impacts affecting the rear of the helmet represent about 10% or more [11] (page 278 of the document or 288 of the PDF). I'd note that most intepretations of the data e.g. [12] [13] [14] generally consider regions containing the rear side including the rear I'm guessing because this makes the most sense (i.e. it isn't uncommon that impacts will affect at least part of the rear). If you did want a region of the helmet not generally impacted, try the top. Nil Einne (talk) 11:30, 8 June 2017 (UTC)

I don't know if this is the reason (some) helmets are shaped like that, but I'll note that a sphere is not the most aerodynamic shape. A "teardrop" or airfoil shape, with the point at the rear, has less aerodynamic drag than a sphere.[15] Some helmets approximate that type of shape. CodeTalker (talk) 15:58, 8 June 2017 (UTC)

 

I don't have references to hand; someone can probably find them by an easy search, but I think it might be worth mentioning that often the function of aerodynamic-looking stylings is simply to look aerodynamic (and be stylish).

For some time, a lot of new cars had spoiler-like things in back, like you would put on a race car to provide negative lift and keep the car from launching into the air. These passenger cars had no use for that feature whatsoever. But buyers liked the look. --Trovatore (talk) 21:54, 8 June 2017 (UTC)

How fast could a human swim in an infinite universe made of STP air?

How many minutes or hours of swimming would it take to accelerate till air resistance equals average swimming power? Would his air disturbances and/or body mass cause a black hole to form? How long would that take? He starts at zero airspeed. Sagittarian Milky Way (talk) 22:26, 7 June 2017 (UTC)

Bees tread air like swimmers tread water, but their top speed will not possibly be much faster than the speed that they can rotate their wings or arms or undulate their bodies since one has to be able propel the air with respect to the zero air speed to at least their current speed or more in order to have thrust. Otherwise their effort will simply serve to act as a net drag (like sticking your hand out of a car window). To look at this another way, what is the top wind speed of the air leaving their cupped hands when they slap at the air or from their lungs when they are stationary. They will never exceed that speed and become fast and massive even if the air resistance was negligible due to an aerodynamic suit. --Modocc (talk) 23:38, 7 June 2017 (UTC)

Could random turbulence and the tiny high density seed (a human) at the center of the initially isotropic, windless universe cause a positive feedback loop of gravitational collapse? (maybe long after he's dead?) Or would air flowing from high pressure to low prevent any gravitational accumulation of an air planet that becomes a nitroxygen star that becomes a white dwarf that becomes a neutron star that becomes a black hole? Air pressure changes only travel at the speed of sound so maybe gravity can overcome it? Sagittarian Milky Way (talk) 23:53, 7 June 2017 (UTC)

Gravity is so weak the local pressure gradient due to the displaced air would be negligible. Thus, I don't see that happening. The long-term outcome would certainly depend on how independent and random the air molecules' trajectories actually are. Nevertheless, I'll conjecture that they don't have sufficient independence to spontaneously sustain localized disturbances as such. However, I could be very wrong on that as I'm not a physicist or a cosmologist. --Modocc (talk) 01:26, 8 June 2017 (UTC)

STP may be "The Racer's Edge" but I wouldn't recommend swimming in it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:41, 7 June 2017 (UTC)

(standard temperature and pressure). Sagittarian Milky Way (talk) 23:54, 7 June 2017 (UTC)

• The question is meaningless (to say the least); velocity is relative, there would no point of reference against which to measure the speed. There does seem to be a black hole involved here, but not a cosmological one. μηδείς (talk) 02:15, 8 June 2017 (UTC)

We are each at rest relative to the average velocity of the air molecules we are now breathing in the rooms we are in. Simply ignore or remove the movement of the celestial sphere and extend your walls to infinity and we are still at rest to their average velocities for an infinite amount of air with the gravity evenly distributed thus canceling. Move very fast relative to that reference and you will suffer from air resistance. Period. It's a thought experiment, so your mileage may vary. --Modocc (talk) 02:29, 8 June 2017 (UTC)

No, this is simply college dorm bullsittery. You are now adding ad hoc assumptions to deal with possible objections. If all the air is still, then all that will happen is the creation of eddies local to the flailing body, not "swimming" and not any objectively measurable velocity. μηδείς (talk) 17:48, 8 June 2017 (UTC)

The OP's thought experiment is simply an infinite universe filled with breathable air and with a swimmer in it. From the swimmer's perspective it would be little different than living in a dark space station filled with air that is several miles in diameter where there is no gravity so they are floating in the middle of it of it all. Then they can get the ground pepper (inspired from the more recent thread posts below) and sneeze a lot in one particular direction such that they move in the opposite direction. Better yet they can use a rapid down stroke such as with the breaststroke and since there is not much to kick wear the flippers that divers use. I wore them for fun and for swimming speed when I was a kid. Boat propellers such as what's on airboats work on the same thrust principle. It's basic Newtonian mechanics, and at some point, some knowledge about air molecule velocities of the Maxwell–Boltzmann distribution. When the molecules' velocity vectors are summed the mean amplitude is near zero because the stationary swimmer is being impinged equally by air molecules from all directions; half the molecules velocities are negative and the other half are positive. As the swimmer gains velocity this is no longer true and they experience a net force due to the air resistance. In this case, changing to a reference frame in which the swimmer is always stationary, the mean amplitude of the molecular velocities will become nonzero in the direction opposite of their movement. Since the air resistance is a drag force they will eventually slow down such that the mean amplitude is zero again (in their reference frame). Unless, they come into possession of a perpetual motion machine. Now that would be an invention! -Modocc (talk) 19:39, 8 June 2017 (UTC)

No, again, there is nothing to measure one's velocity against, and the simplest assumption is that the air surrounding your body would simply move in local vortices as you flailed about. Everything else depends on smuggling in assumptions the OP has not made. This is why we don't engage in speculation or debate. There's no definable "location" in this universe, and at STP any single molecule of air is moving in a random walk at 1,000's of kmph. Again, the premise is pre-scientific, one might as well argue about the clinamen, phlogiston, and aether. μηδείς (talk) 21:41, 8 June 2017 (UTC)

I adequately answered the OP's question with my first post and the only reason this thread is continuing is to rebut your unfounded assertions. Molecule collisions happen to conserve momentum so they are not as random as one might think. Nevertheless these molecules do move relative to one another and the swimmer so it's not like there is nothing to measure. Your first post here was to assert "there would no point of reference against which to measure the speed" which is a misconception that you are still repeating with "there is nothing to measure one's velocity against" although I've gone to great pains to debunk this. Let's give the swimmer a rocket so they can create sonic booms when they are not at rest. --Modocc (talk) 21:51, 8 June 2017 (UTC)

Averaging the velocity of all the air molecules out to infinity gives a frame of reference to measure speed against. Sagittarian Milky Way (talk) 23:00, 8 June 2017 (UTC)

Sagittarian Milky Way, that is very well stated and there are times when I wish could be that succinct and didn't delve into peripheral tangents and be misunderstood. :-) -Modocc (talk) 00:05, 9 June 2017 (UTC)

At the other extreme, swimming in a highly resisting medium has been put to the test [16], though this addresses only ultimate velocity and not the time needed to approach it,--catslash (talk) 01:18, 9 June 2017 (UTC)

Consideration of dimensionless numbers in fluid mechanics and dimensional analysis might provide an estimate of the ultimate velocity and time needed to approach it. --catslash (talk) 01:32, 9 June 2017 (UTC)