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October 18

In a li-ion battery, does the chip distribute the tear and wear?

In common mainstream li-ion batteries, does the controller distribute the use across all cells all the time? Or could it be that one cell gets weared out sooner than the others? That is, could a used battery have some cells that are still good, even if the battery has lost 30-40% of its capacity? --Llaanngg (talk) 17:56, 18 October 2016 (UTC)[reply]

Here's an excellent web resource: This Week in Batteries, an informal blog maintained by the fine folks who run the Chemical Engineering 198 class, Battery Technologies and Markets, at Berkeley.

They have a lot of great resources to help you understand modern battery management systems - the engineered devices around the electrochemical cell that make sure the cells are operating correctly.

It would be irresponsible to categorize all lithium-ion battery systems into the same bucket - there are immensely variable configurations in modern systems. Some battery management and power-supply systems certainly perform load balancing.

One of the easiest, simplest, most straightforward ways to do load-balancing is to connect the cells in series. There is a good reason, based on solid fundamental science, to explain why this works so surprisingly well - but it has alarming shortcomings and serious impact to total system performance.

Nimur (talk) 18:27, 18 October 2016 (UTC)[reply]

From the publication list hosted at National Renewable Energy Laboratory, here is Modular approach for continuous cell-level balancing to improve performance of large battery packs (2014), available at no cost from IEEE. NREL actively investigates and sponsors research in battery control algorithms, including active cell balancing technology. Nimur (talk) 00:19, 19 October 2016 (UTC)[reply]

The OP's question is a concern common to the thousands of owners of the ageing but popular Toyota Prius hybrid electric cars. Individual cells of the series-connected Li-Ion traction battery do indeed wear out (lose capacity) prematurely. The on-board diagnostic program gives an error code when it detects imbalance. There are video guides[1] [2] [3] on line about how to rejeuvenate the battery by replacing individual cells but it must be warned that this requires working in a high voltage circuit that is dangerous for an amateur without full knowledge and precautions. The manufacturer's battery warranty will not cover an unauthorized repair. AllBestFaith (talk) 12:59, 19 October 2016 (UTC)[reply]

The BMW i3 has an active cell balancing mechanism to ensure that all cells are correctly managed. See https://issuu.com/brycheinsltd/docs/evs_and_i3 for details.--Phil Holmes (talk) 14:36, 19 October 2016 (UTC)[reply]

What are "common mainstream li-ion batteries" these days? It's a fast-moving field, it's hard to know.

Many battery packs, even single cells, incorporate a protection board whose main function is to avoid over-discharging the cell, either too quickly (too much current, risk of letting the smoke out) or for too long (damaging the cell). This doesn't have a balancing function though. Larger capacity multi-cell packs (radio control models are a leading example) have a separate connector with the inter-cell connections, used to balance the cells during charging. The balancing is done by a smart charger, not an on-board controller or protection circuit.

Where developments seem to be going now though are to avoid the traditional series-connected battery, in favour of single cells and a DC-DC boost converter to produce the voltages needed. For Li-ion (unlike lead-acid) it's also possible to make a battery pack by parallel connection of cells, giving the energy capacity needed, and avoiding balance problems, and letting the DC-DC converter deal with voltage. Andy Dingley (talk) 10:21, 20 October 2016 (UTC)[reply]

October 19

Feynman Lectures. Lecture 32. Sec. 32–5 Scattering of light [4]

Quote: Now we can make an experiment that demonstrates this. We can make particles that are very small at first, and then gradually grow in size. We use a solution of sodium thiosulfate (hypo) with sulfuric acid, which precipitates very fine grains of sulfur. As the sulfur precipitates, the grains first start very small, and the scattering is a little bluish. As it precipitates more it gets more intense, and then it will get whitish as the particles get bigger. In addition, the light which goes straight through will have the blue taken out. That is why the sunset is red, of course, because the light that comes through a lot of air, to the eye has had a lot of blue light scattered out, so it is yellow-red. Unquote.

I need advice to check have I correctly understood. The light when is going through the atmosphere is absorbed and re-emitted (scattered ) by atoms' electrons. There is the formula

$\sigma _{s}={\frac {8\pi r_{0}^{2}}{3}}\cdot {\frac {\omega ^{4}}{(\omega ^{2}-\omega _{0}^{2})^{2}}}$

According to it blue light takes 16 times more scattered energy than red light, as the blue has 2 times higher frequency. But frequency ω that enters into the formula is the frequency of scattered light. So (1): where is blue light from incident beam? I've found several demonstrations on youtube (e.g. youtube.com/embed/LSf7iRD5Jws ). And it looks like the light from a lamp loses blue. And (2): even if blue light re-emitted more intensively, last layer of atoms before eye must absorb red light and re-emit white light. So we have the statement that light keeps its frequency and ω_incident = ω_scattered . (3) When a wave goes through an atom, electrons begin to oscillate and emit: https://s.sender.mobi/u/image/2016/10/19/wl-chKHAa/-.PNG . Electrons emit in all directions in sheet plane whole absorbed energy, but 16/17 of it is blue and 1/17 of it is red light. Then the light from a lamp (which goes form right to left) must lose same amount of blue light as was emitted by electron.

Is it correct?

Username160611000000 (talk) 04:07, 19 October 2016 (UTC)[reply]

Yes, the light loses mainly blue frequencies as it passes through a scattering medium and becomes redder. Ruslik_Zero 19:54, 19 October 2016 (UTC)[reply]

But we know that electric field acts on the charges, not paying attention to the barrier. So oscillating electron emits such a field that the incident waves (490-445 nanometres) is damped. Is it correct?

Waves 740-620 nanometres (red) makes the electron oscillate with frequency 400 THz. Waves 490-445 nanometres (blue) makes the electron oscillate with frequency 670 THz. But amplitude of oscillations in second case is higher in (670/400)² times. Is it correct? But it's unnatural for oscillator. We know that displacement (thereby amplitude) is proportional to force. Or for atom we should use http://www.feynmanlectures.caltech.edu/I_12.html#Ch12-F2 ? Username160611000000 (talk) 16:00, 20 October 2016 (UTC)[reply]

Is that true that for increasing testosterone it's good to eat a lot of fats?

Is that true that for increasing testosterone hormone it's good to eat a lot of fats (or food which rich with fats)? I saw a youtuber which said it but I don't believe anything without scientific evidence. I would like to ensure or deny it. thank you 93.126.88.30 (talk) 19:34, 19 October 2016 (UTC)[reply]

Looking into a general google search for "Dietary effects on testosterone" leads to a lot of sketchy weight building sites with not a lot of hard science. However, using Google Scholar, I was able to find a few interesting published studies. This one is from an older study (1979) but otherwise looks solid, stating "A lower nocturnal release of prolactin and testosterone occurred in men fed a vegetarian diet" while this one from 2008 states "high-fat fed rats showed significantly lower total values of plasma TSH and testosterone" which would seem to indicate the opposite of what your random YouTuber claimed. This article from 1987 seems to indicate the controlling factor is not fat at all, but protein/carbohydrate ratios in the diet. Just some places to research your question. --Jayron 32 19:53, 19 October 2016 (UTC)[reply]

More to the point, why should anyone care? If you have actual androgen deficiency, consult a medical professional. Otherwise, there's no real reason to care about your testosterone level. There are loads of "broscience" passed around in the world of bodybuilding, etc. which is pretty much all bullshit. If you want to maintain good health, eat a well-balanced diet and get regular exercise. --47.138.165.200 (talk) 01:47, 20 October 2016 (UTC)[reply]

As always, it's horrible to ask here questions regarding to medical science (without any personally aspects). Someone always should make other fear of answering without any reason. I asked my question because the claim felt to me strange.This is the Youtuber in this video. 93.126.88.30 (talk) 02:06, 20 October 2016 (UTC)[reply]

If you listen to the whole video and put the fat issue in context of everything he says, then it's just the normal advice. The standard advice is to limit saturated fat intake, replace such fats by mono and poly unsaturated fats. Eating nuts such as walnuts as suggested in the video is consistent with the standard advice. One can argue about whether this is really true, because only the Omega-3 and Omega-6 fats are essential fats, our bodies can make all the other fats it needs from eating carbs. But, of course, you do need to eat enough calories and most people will struggle to do so if they don't eat any fat. Count Iblis (talk) 21:02, 20 October 2016 (UTC)[reply]

Can dead bodies infect life bodies with hepatitis or HIV?

may dead bodies infect life bodies with hepatitis or HIV? I'm asking it because I have a doubt if this viruses need nutrition or oxygen etc. in order to exist. 19:37, 19 October 2016 (UTC) — Preceding unsigned comment added by 93.126.88.30 (talk)

This forum discussion has some excellent references to research on the matter. Here is a more general overview form the World Health Organization, and Here is another source specifically for HIV. Wikipedia also has an article titled Health risks from dead bodies which has some brief statements to this effect, but also leads to more reading if you follow the references. --Jayron 32 19:45, 19 October 2016 (UTC)[reply]

Just a little grammatical aside — you mean "can dead bodies infect....". I know the can/may distinction is a little tricky for some non-native speakers, as not every language has it (not sure about Ukranian). Anyway, you should use may for permission or moral or legal acceptability, can for physical possibility or practical feasibility. --Trovatore (talk) 19:52, 19 October 2016 (UTC) [reply]

Thank you93.126.88.30 (talk) 01:49, 20 October 2016 (UTC) [reply]

Yes it can. Very easy to prove. Just because the person died 10 seconds ago does not mean their body cannot infect your body with hepatitis or HIV if you have unprotected sex with the corpse. 175.45.116.99 (talk) 06:00, 20 October 2016 (UTC)[reply]

I think the main point of this question remains unaddressed. A virus, according to most definitions, is not even really "alive", it certainly does not require nutrition OR oxygen in order to exist. Most viruses however, including HIV require an alive host and don't survive a long time OUTSIDE of living cells. So a key point here is that "death" is not an instant process, when a person dies, many cell functions continue to operate for at least some length of time. It appears that HIV can take as little as 1-2 days to "inactivate" in a corpse, but can survive much longer (a week or even more) under some circumstances, such as refrigeration. Vespine (talk) 21:59, 20 October 2016 (UTC)[reply]

Are there any reports (preferably scientific reports) which talk about the amount of pain that a person with prosthetic balls suffers when he gets kicked in the balls?

Apologies if this is a stupid question; however, I am genuinely curious as to whether or not people with prosthetic balls experience as much pain as people with natural/biological balls experience when they get kicked in the balls.

Anyway, does anyone here have any thoughts and/or data in regards to this? 128.195.178.33 (talk) 22:13, 19 October 2016 (UTC)[reply]

Here is a discussion forum on prosthetic testicular pain. --Jayron 32 22:36, 19 October 2016 (UTC)[reply]

October 20

Surviving a 130-degree hyperthermia

I believe it's possible that people can survive a 130-degree F hyperthermia. I speculate there was a person whose body temperature reached 133 deg. F and survive, which is a world record for the highest body temperature to reach and survive. What do you think of this oddity? Planet Star 04:51, 20 October 2016 (UTC)[reply]

Where did you see the 133 degrees report? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:52, 20 October 2016 (UTC)[reply]

That was merely my guess and I did not see the report of that. Planet Star 22:28, 20 October 2016 (UTC)[reply]

Apparently, the highest recorded non-fatal body temperature was is 115.7°F (46.5°C) achieved by one Willie Jones of Atlanta in 1980. Our article Orders of magnitude (temperature)#Detailed list for 100 K to 1000 K cites this website, which cites the Guinness Book of Records. This is a rather more reliable citation for a body temperature of 113°F (45°C). But nobody has survived anything close to 130°F. Tevildo (talk) 05:54, 20 October 2016 (UTC)[reply]

The OP may be misremembering reports of survivable sustained external temperatures, which of course can be much higher than internal temperatures, particularly in an experimental laboratory setting. {The poster formerly known as 87.81.230.195} 90.197.27.88 (talk) 15:09, 20 October 2016 (UTC)[reply]

One demonstration (I can't find the ref at the moment) had a man and a steak in a high temperature chamber. The steak ended up cooked while the man was unharmed. IIRC they kept the humidity near 0%, had a large fan blowing air over man and steak, and allowed the man to drink a lot of water and take pills to replenish water and electrolytes lost through sweating. So it was basically a demonstration of how well sweating cools you. --Guy Macon (talk) 04:38, 21 October 2016 (UTC)[reply]

Staying with a Finnish family many years ago, they cooked their sausages by hanging them in the sauna while we were using it. Our article suggests that the air temperatures in a Finnish sauna are "typically between 70 and 100 °C" (158 and 212 °F). It was certainly bloody hot. Alansplodge (talk) 11:08, 22 October 2016 (UTC)[reply]

Were they higher then you where hot air rises? Sagittarian Milky Way (talk) 16:21, 23 October 2016 (UTC)[reply]

About head height when we were sitting down, if I recall correctly. The difference was that we got up and jumped in the lake every fifteen minutes or so and then drank some beer before going back again, while the sausages stayed there all afternoon. Alansplodge (talk) 20:55, 23 October 2016 (UTC)[reply]

Charles Blagden first performed this experiment in 1775 (ref), although it's doubtless been performed under more controlled conditions since then. Tevildo (talk) 12:42, 22 October 2016 (UTC)[reply]

Walk thousands of miles without losing weight

I think it's possible to walk from New York to Los Angeles without losing a single pound. Do you agree? Planet Star 04:51, 20 October 2016 (UTC)[reply]

In how much time? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:52, 20 October 2016 (UTC)[reply]

Besides what BB has said, it depends on what your body was like before you started, what & how much you eat and drink and how all these (including exercise) were before you started this journey, etc. But the answer is surely yes if you don't have any restrictions. Plenty of people put on weight despite regular exercise. (Actually it can be quite easy to put on weight if you hardly exercise at all and weren't very overweight due to increasing muscle although walking from New York to LA would generally be a resonable amount of exercise.) The driving distance between New York and LA is only ~4500 km [5] which means if you take 13 years it's only about 0.95 km a day which is by no means a lot. Nil Einne (talk) 06:36, 20 October 2016 (UTC)[reply]

if you connect your body to a source of automated nutrition suppply set at isotone (crysis nanosuit, halo spartan model), then yes.Minimobiler (talk) 12:22, 20 October 2016 (UTC)[reply]

The ancient Roman weight unit libra or pound, equal to about 328.9 g, was adopted as a coinage unit "Tower pound" (of silver) in the reign of King Offa of Mercia and is source of the £ abbreviation of £sd i.e. £ibrae, solidi, and denarii. Traveler's cheques for values in pounds were first issued in 1772, can still be bought[6] and are touted as "Completely safe: if they get lost or stolen they'll be replaced.". Their issuers of these un-losable pounds never mention the pounds they gain in interest from lending the pounds you paid them to other borrowers, which is part of the reason for declining use of the cheques. AllBestFaith (talk) 16:38, 20 October 2016 (UTC)[reply]

Obese people will need to lose weight before they can reach the physical fitness required for this. Count Iblis (talk) 20:20, 20 October 2016 (UTC)[reply]

Again, without any restrictions this is surely wrong. If we're talking about classicial definitions like those using BMI, obesity covers a very wide range of physical conditions. 0.95 km is hardly a lot of exercise. (It's probably enough that many, but not all, obese people will lose weight again dependent also on all the conditions before and during.) If we expand it even further, we can get it down to 0.4 km which if you start at age 20, will mean you're still far from elderly before you finish. And 0.4 km is hardly that much exercise at all. Of course you need some way to get the food and someone to rest in between, which is perhaps what Minimobiler was getting at but again without restrictions you could sleep in a campervan or something and the food and water could be brought to you, likewise the campervan cleaned etc. Even if you're using stricter definitions of obesity, AFAIK most of them would still allow someone who can walk 0.4 km or 0.95 km a day to be obese. Of course at the outer range, you have people who can't even get out of bed, but you said obese people, not severely obese people. Nil Einne (talk) 02:20, 21 October 2016 (UTC)[reply]

Dunno about your definition of Obese, but with a BMI of 36 I used to go walking for 7 days carrying my own tent and food (22kg pack), and rarely lost weight. I did lose weight when I walked to Everest base camp, probably slight dehydration, it was only a couple of kg. Greglocock (talk) 06:36, 22 October 2016 (UTC)[reply]

copper pot vs copper pot filled with water

which helps cool or melt things faster? — Preceding unsigned comment added by Minimobiler (talk • contribs) 12:19, 20 October 2016 (UTC)[reply]

Water has a higher specific heat than copper. That should help you figure out how each responds to changes in temperature. --Jayron 32 12:24, 20 October 2016 (UTC)[reply]

but the conduction rate. it is lower, much. — Preceding unsigned comment added by Minimobiler (talk • contribs) 12:37, 20 October 2016 (UTC)[reply]

Conduction rate is controlled by Newton's law of cooling. --Jayron 32 12:38, 20 October 2016 (UTC)[reply]

We can also write Fourier's law, (which simplifies down to Newton's law in many cases), but also accounts for a material-specific conduction constant.

I think we need the original question to be phrased more precisely and specifically before we start lobbing equations at it. Are you envisioning a copper pot on a stove, with new heat being added? How much water? What are you heating? At what temperatures? ...and so on. These details will impact the way we model the heat transfer, which might change the answer you're looking for.

For example, last week I took a safety training class at my local fire station, and I learned all about flashover. In a small kitchen fire, heat is conveyed convectively and conductively as hot material physically touches other flammable fuels, and as hot flame and smoke billow around the environs. But in a really big fire (like when the whole room starts burning), the temperatures rise really rapidly. Thanks to the Stefan–Boltzmann law, we know that infrared emission, like all other electromagnetic radiation, rises with the fourth power of temperature - so once your room is up to, say, a thousand degrees, a great quantity of heat starts travelling at the speed of light. This is faster than conductive heat transfer; it is faster than convective heat transfer; it is faster than supersonic detonation. ...And this "exotic" mode of heat flow occurs during ordinary structure-fires. When flashover occurs, it becomes the primary mode of ignition - even if only a small percentage of total heat transfer (in joules) occurs by this mode, it occurs so rapidly (think about watts, or joules-per-second, at the characteristic time-scales of a beam of infrared traveling across your room).

So if you're cooking your copper pot inside a house fire, we can't use simplified math: we have to go back to first principles of physics. How does heat flow? (Heat conduction, convection, and radiation). How do we quantify the rate of heat flow for each mode? (Our articles point you toward the right equations). In which circumstances can we totally ignore some of the details, and use a simpler equation? (This would be a great homework question!)

Nimur (talk) 14:52, 20 October 2016 (UTC)[reply]

If you put wings on to a Tesla, would it fly?

If you put the drive train from a Tesla and put it into an airplane, would it fly?

The Tesla Model S P100D does 0-60 mph in only 2.5 seconds. It has 760bhp, but it weighs 2,100kg - of that, about 500kg is battery. It has a range of maybe 300 miles and costs US$135,000. By comparison, a Cessna 172 has four seats and weighs 800 kg to 1,100 kg, depending on fuel/cargo. It will cruise at 140 mph, but it only needs 160 bhp.

Pigs can't fly, but what if you put wings on a Tesla?--2A02:C7D:42AB:3800:253B:991C:30A:30E6 (talk) 17:18, 20 October 2016 (UTC)[reply]

Can assure you that pigs don't have any trouble flying as long as they can gain enough kinetic energy to get off the ground. Here, in the UK we have often flown cars too. [7]--Aspro (talk) 22:06, 21 October 2016 (UTC)[reply]

Actually, some pigs can in fact fly. 2601:646:8E01:7E0B:40E5:EEF0:65B8:D229 (talk) 23:17, 23 October 2016 (UTC)[reply]

Wikipedia has an article titled Flying car (aircraft) which covers both speculative and actually build flying cars. --Jayron 32 17:23, 20 October 2016 (UTC)[reply]

See also Electric aircraft for some real-world examples. Tevildo (talk) 17:59, 20 October 2016 (UTC)[reply]

Homebuilt aircraft can have many different types of motors, including chainsaw and motorcycle motor, so I would not be surprising to see a flying plane with a Tesla motor. However, as the LA Times reports, electric airplanes still have some challenges before it. --Llaanngg (talk) 12:56, 21 October 2016 (UTC)[reply]

A fuel cell could probably be more effective as a power source than a battery in terms of having a better weight/energy ratio. Roger (Dodger67) (talk) 13:18, 21 October 2016 (UTC)[reply]

Note that you would need to add a lot of weight to the Tesla in the wings, if they are to be big enough and strong enough to support the weight of the car, and include all the controls and control surfaces needed to steer a plane. StuRat (talk) 17:22, 23 October 2016 (UTC)[reply]

October 21

Two questions after watching Disney's Tarzan...

What mammals other than Man reach sexual maturity and/or full growth after age twelve? Elephants?
Is there a significant difference among the milk of the great apes (compared to the difference between Human milk and Cow Milk?

Naraht (talk) 04:58, 21 October 2016 (UTC)[reply]

For 1, [8] suggests female Asian elephants and some male Asian elephants achieve sexual maturity after twelve. (But some humans do achieve sexual maturity before 12.) African elephants [9] [10] seem to often be before 12 years. I'm not sure how reliable this source is [11] [12] [13], but I believe it's correct that elephants are not fully grown at this stage and therefore male elephants at least rarely mate at this age. Nil Einne (talk) 08:33, 21 October 2016 (UTC)[reply]

My guess was the blue whale but "The blue whale reaches sexual maturity at around 10 years of age." [14] Alansplodge (talk) 11:04, 21 October 2016 (UTC)[reply]

Male sperm whales "become sexually mature at 18 years" according to the article, or "between 18–21 years" according to the Australian Department of the Environment and Energy for instance. For female sperm whales the corresponding ages are given as "9" / "between 7–13". ---Sluzzelin talk 12:35, 21 October 2016 (UTC)[reply]

For 2, The constantly protruding breasts of the adult human female differ from the mammary glands of other Primates that protrude only while actually filling with milk, and are presumably the result of evolutionary sexual preference by males, see Mammary gland#Other mammals. In this article studies on the milk of primates, especially in comparison with human milk, are reviewed. This article reviews primate lactation biology and milk synthesis to identify the derived and ancestral features of primate milks. This report elucidates the structures of free milk oligosaccharides so that they can be related to glycan function in different primates. AllBestFaith (talk) 13:13, 21 October 2016 (UTC)[reply]

This is a sidetrack, but it's useful in pointing out the distinction between breast and mammary gland. The former article currently says "In females, it serves as the mammary gland..." which makes me wince, not just because men can (rarely) lactate effectively, but because the breast contains fatty tissue that is not part of the gland. And indeed, the human breast is specifically designed to stand out on its own, without lactation activity! Not entirely easy to find a good source to cite for this distinction though. Wnt (talk) 17:27, 22 October 2016 (UTC)[reply]

What makes wasabi difficult to cultivate?

My friend told me today most wasabi comes from horseradish - and the Wikipedia article backs this up. This is attributed to the wasabi's cost and rarity, which is due to difficulty in its cultivation...but the article does not provide reasons why. Thus, the header question. I would appreciate any insight into this question. Thank you! Rotideypoc41352 (talk) 20:17, 21 October 2016 (UTC)[reply]

http://www.thewasabicompany.co.uk/wasabi-plants/wasabi-plant are the people to ask. Seems that it has been something of of an occult art until recently, but they claim to have made it practical, both for their commercial production, and for home-grown. Andy Dingley (talk) 20:38, 21 October 2016 (UTC)[reply]

Agree with Rotideypoc41352 that this article is lacking. As to the cultivation bit, that is easy to answer. Both Wasabi and Horseradish need the right soil conditions in order to provide an economic viable crop yield. Most farm land doesn't provide those ideal conditions regardless of how much fertilizer etc one spreads.. Just as trying to cultivate watercress in the Sahara Desert is very difficult too. I have grown horseradish but it need to be grown in a corner of the garden were the soil is always damp and with a low pH.--Aspro (talk) 21:04, 21 October 2016 (UTC)[reply]

Talking of damp... Looking at File:Izu city, Ikadaba, Wasabi fields 20111002 C.jpg have you noticed that the commercial plantation depicted in that image is on a stream bed. IE., very moist with a low pH. Opposite example: One can't convince a rhododendron to grow in most of Kent as the soil doesn't suit them (pH too high) . Rhododendron.Org --Aspro (talk) 21:32, 21 October 2016 (UTC)[reply]

I have visited a wasabi farm in Japan. Wasabi is typically grown in running water such as a stream bed with a constant water temperature of between 12°C (54°F) and 14°C (57°F). Anything outside of 8°C (46°F) and 20°C (70°F) and the plants will die.[15][16][17] --Guy Macon (talk) 21:49, 21 October 2016 (UTC)[reply]

Exactly. So, coming back to the OP's question. Rather than the article stating that “Wasabi is difficult to cultivate” it should read something like “Wasabi favours growing conditions which restricts its wide cultivation. The resulting inability to fully satisfy commercial demand, thus makes it quite expensive”. Or something along those lines – with some ref's. Should this discussion not be now transferred to this articles talk page? How does one do that?--Aspro (talk) 22:38, 21 October 2016 (UTC)[reply]

It probably should not be taken to the Talk page. Talk pages are for discussing what should be in the article. This seems to be a general question about production of wasabi. If the OP or other editor wants to question whether the article should contain content about the production, that should be on the Talk page. DrChrissy ^(talk) 22:50, 21 October 2016 (UTC)[reply]

The OP's question has alerted us, that this article is deficient enough to warrant him asking this question. Why he didn’t post this on the article's talk page I don't know. Yet, a better, explanation should be in this article – which I don't think the OP would disagree with – otherwise he would not have needed to ask – in the first place – and where do we have those discussions if not on the talk page? --Aspro (talk) 23:26, 21 October 2016 (UTC)[reply]

I guess it depends on the motivation of the OP for posting the question. If they intend to edit the article with information on production, yes, the question should have been posed at the Talk page. If the OP was simply wanting to know why there are problems producing wasabi, then this is probably the correct place. I have to admit, I have not even read the wasabi article so I did not know this information was missing. I do not feel strongly about this at all so please feel free to move this thread to the Talk page if you wish - I will certainly not challenge that. DrChrissy ^(talk) 23:35, 21 October 2016 (UTC)[reply]

My feeling (per Aspro) is that if an OP asks a question on a RefDesk about a subject whose article they have linked (and presumably therefore read, as is explicitly stated in this case), it's prima facie evidence that the article is probably lacking and/or unclear in some fashion (assuming no trolling, which is certainly not the case with Rotideypoc41352's query).

While no volunteer on the RDs is thereby obliged to go and improve the article, it's a clear signal that improvement is desirable, and potential article editors are free to continue on the article's talk page, or one of them could just boldly go ahead and fettle it.

This doesn't mean that the OP wasn't right to ask at the RD in the first place: for most users (IP or signed up), the RDs are for supplying wanted information – that some of us may also utilise RD queries as a steer to improving articles is an added benefit, not a rival purpose. {The poster formerly known as 87.81.230.195} 90.197.27.88 (talk) 02:37, 22 October 2016 (UTC)[reply]

Whenever I see a question like the OP's asked on an article talk page, I take it as implicit that it is saying "This article is deficient. What information do we need to add to fix this?" However, I quite often see people get told off for asking such questions ("The talk page is for discussing improvements to the article. If you have general questions about the subject go to the Reference Desk") if they don't spell that out. Iapetus (talk) 09:13, 24 October 2016 (UTC)[reply]

October 22

Frozen Virus

With random stories appearing every now and again about Ice melting and releasing some Dinosaur era virus to wipe out humanity was woundering if that was even possible...I understand several species can freeze and come back to life so to speak but long term would have thought the freezing process would destroy the internal workings of life of a sustained period of time; also that it would have to mutate to this environment. With that said would have thought it neigh on impossible for said destruction of humanity. If this is not the case why can we not cryo freeze the human body with out damaging it? — Preceding unsigned comment added by 5.175.72.42 (talk) 05:31, 22 October 2016 (UTC)[reply]

Viruses do not have a metabolism, some types are able to still be viable after long freezing. There are legitimate concerns about the graves of victims of the 1918 flu pandemic in the permafrost of Arctic regions thawing and releasing the virus.^[1] Similar concerns about smallpox have also been raised in scientific literature.^[2] -- Roger (Dodger67) (talk) 09:08, 22 October 2016 (UTC)[reply]

References

^ Taubenberger, Jeffery K; Hultin, Johan V; Morens, David M (1 January 2007). "Discovery and characterization of the 1918 pandemic influenza virus in historical context". Antiviral therapy. 12 (4 Pt B): 581–591. ISSN 1359-6535. PMC 2391305.
^ Stone, R. (15 March 2002). "PUBLIC HEALTH: Is Live Smallpox Lurking in the Arctic?". Science. 295 (5562): 2002–2002. doi:10.1126/science.295.5562.2002.

Frozen for a few hundred years might leave a risk - but not from the time of the dinosaurs. Given the movement of tectonic plates and the changes in planetary climate over the millions of years since then I do not believe that there can be anywhere on the planet which has remained consistently frozen over that period. Wymspen (talk) 11:46, 22 October 2016 (UTC)[reply]

Oh my, we do not have an article on Paleo DNA. This must be remedied. (Is there something to redirect to that I missed?) But while Neanderthal DNA has been isolated, it is very difficult to find large intact pieces (how difficult, honestly, I have to look up still). So the odds of getting a complete viral genome together capable of infecting someone, even from that era, are astronomically low unless some busy beaver is splicing it together and filling in the gaps on his computer. And of course a virus still has a really hard time infecting someone without its proteins, which in many cases won't survive intact either.

The joke though is that a virus much older than that, if deadly, would be very questionable in the first place. If it was deadly enough to select the human population, then modern humans might carry natural immunities that became fixed in the population. And if it predates humans entirely, there's no telling if it can jump the species barrier at all. So the viruses we get to actually worry about being intact, like smallpox scabs set aside in an envelope, [18] are also the ones most likely to be able to kill us.

See Ancient DNA. Anything very old is damaged and not viable. The DNA strands become broken or crosslinked. Radiation from cosmic rays or potassium can supply the energy. Graeme Bartlett (talk) 02:32, 23 October 2016 (UTC)[reply]

Even if somehow an ancient pathogen were to emerge, it would almost certainly be harmless. Our bodies have evolved defense mechanisms from the time life first evolved 4 billion years ago to deal with such threats. The fundamental biochemical mechanisms are actually designed to deal with random threats that could derail it, it's not the case that we can only defend ourselves against a limited number of known threats, this is a misunderstanding based on the way the adaptive immune system works (which only evolved a few hundred million years ago). Here one then focuses only on the limited number of pathogens that our bodies are susceptible to, our immune systems need to deal with those pathogens and one wrongly imagines that all microbes out there are like that. But the dangerous pathogens are the result of an arms race where they try to outsmart our defenses and where our immune systems try to come up with ever more sophisticated defenses. These are the one a billion exception to the random microbes were are subjected to every day.

So, a random virus would be extremely unlikely to be do any harm to our bodies, for the same reason why a random person walking toward the entrance of the Pentagon would likely be stopped before he could inadvertently walk in, and if somehow he could walk in, there is no way he would be mistaken for a Ash Carter, and even if somehow that would still happen, there is no way he could actually do some real damage by inadvertently acting like Ash Carter. Obviously a successful impostor would need to have lots of information about the system before it could successfully enter and derail it. That information cannot have come out of thin air, it must have come from the system itself. Now, you can have viruses like the Ebola or HIV virus that are adapted to other animals that can cause deadly infections. But such cases are extremely exceptional, they involve a virus that has adapted to an evolutionarily relative to us. A dormant virus that has never interacted with modern mammals is thus unlikely to do any harm to us. Count Iblis (talk) 18:36, 23 October 2016 (UTC)[reply]

Armpit

Why are amrpits dark compared to the skin of the rest of the body? --IEditEncyclopedia (talk) 05:32, 22 October 2016 (UTC)[reply]

There are several pictures in the Axilla and Underarm hair articles that seem to show that they aren't. Rojomoke (talk) 10:14, 22 October 2016 (UTC)[reply]

According to Human skin color#Age, "In some people, the armpits become slightly darker during puberty." This statement is not referenced. Tevildo (talk) 11:33, 22 October 2016 (UTC)[reply]

In my experience (WP:OR alert), it seems to vary a lot. Besides the axilla, the front of the knees and back of the elbows are also places where this occurs in some people. Then in other people, there's nothing like that. See also linea alba and linea nigra for a special circumstance. Matt Deres (talk) 15:37, 22 October 2016 (UTC)[reply]

Another possibility is that deodorants/antiperspirants may discolor the skin. StuRat (talk) 22:43, 23 October 2016 (UTC)[reply]

On the falling bodies

In high school a teacher told me that Galileo had shown with a very simple a priori argument (which he actually showed me), without any need for any experiment whatsoever, that Aristotle's position on the falling bodies could logically only be nonsense. In which of his works does Galileo do that? And, if that is so, what need was there to go drop weights from a tower? Basemetal 11:32, 22 October 2016 (UTC) PS: That argument only shows that the speed of fall has to be independent from the mass. You can not actually derive the fact that the acceleration is constant with that simple argument. It is only meant to show that Aristotle could not possibly be correct. I can repeat it here if that seems useful.[reply]

See Galileo's Leaning Tower of Pisa experiment. The a priori argument appears in Galileo's 1590 book De Motu. Tevildo (talk) 11:39, 22 October 2016 (UTC)[reply]

A modern form of the argument is that according to Aristotle, a parachutist should fall faster with an unfolded parachute than without, because with it he is heavier. But I feel skeptical that concepts like mass, weight, density, and air resistance were really separated that carefully in speech and writing. It reminds me of the logic puzzle about whether a hundred pounds of wet cotton weigh more than a hundred pounds of dry cotton. Any scholar who is too condescending in pointing out about how they weigh the same probably deserves to be sent to go move a few hundred-pound bales of wet cotton and try again. :) Wnt (talk) 13:58, 22 October 2016 (UTC)[reply]

The fallacy there is of course "hundred pound bale of wet cotton" vs. "hundred pound bale of cotton, wetted". Andy Dingley (talk) 09:53, 23 October 2016 (UTC)[reply]

If you said here what exactly the argument is, it might help to locate the source. As for if that is so, what need was there to go drop weights from a tower? - well, that is what experimental science is all about. Even if you are convinced your argument is sound, it does not hurt to check; suprises have happened before. There is a lot to be said about that; one essay I like is Newton's flaming laser sword, that can be summed up as "reality is the best argument". A classical example of experiment that turned out with unexpected results is the Michelson-Morley experiment (although to be fair, the aether's existence was already hotly contested at the time). Tigraan^{Click here to contact me} 15:38, 22 October 2016 (UTC)[reply]

I think it's in the Dialogo sopra i due massimi sistemi del mondo, though the argument that I think you have in mind is not mentioned in that article. —Tamfang (talk) 17:38, 22 October 2016 (UTC)[reply]

People, Tevildo gave the answer about 7 hours ago, about 10 minutes after I'd posted my query. It's in De Motu and the a priori argument is described at Galileo's Leaning Tower of Pisa experiment, just as it was explained to me by my teacher. Sheesh. Life's short enough and there's enough to do. You do not need to give yourself more work than necessary.

Resolved

Triplet paradox

Let there is a triplet of A, B, and C on an asteroid initially. A stays on an asteroid while B and C set out for a long space journey with high speed (say 0.5c and 0.9c) at the same time in the same direction relative to A. Assume each 10 years old at the time of departure. B and C are gone for 60 years relative to A. Afterward, B and C return home at the same time and reunited with A on an asteroid.

What would be the age of A relative to B and C?
What would be the age of B relative to C and A?
What would be the age of C relative to A and B?

Since each person can have only one physical appearance and one age. Thus who would be right?2001:56A:739C:6D00:D418:247C:CE19:4D81 (talk) 03:07, 23 October 2016 (UTC)eek[reply]

What do you mean by "right"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:04, 23 October 2016 (UTC)[reply]

I assume in this case it's "in agreement with observed reality", not "in agreement with the official opinion of the great leader". --Stephan Schulz (talk) 07:55, 23 October 2016 (UTC)[reply]

So each one would be "right". ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:27, 23 October 2016 (UTC)[reply]

Since B and C move out and back again, the two that move are not in an inertial frame of reference - they need to accelerate up to speed, decelerate, turn around, and reaccelerate to go back (and decelerate to come to a stop again). Thus, the three are not in equivalent situations. If you want to take the acceleration into account in detail, you need the general theory of relativity, but you can approximate the result with the special theory of relativity, which will tell you that A will be older than B, which will be older than C. This is just a generalisation of the Twin paradox, which has a fairly good article. --Stephan Schulz (talk) 07:54, 23 October 2016 (UTC)[reply]

Yes, including formulas that should enable the OP to calculate a quantitative answer to his question. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:25, 23 October 2016 (UTC)[reply]

Agreed, but I'm not sure we've understood the question properly. As Bugs said, it's important to figure out what the OP means by "right". There is no "right" age that would be superior to the other two - each of the three would experience idiosyncratic amounts of time away from their siblings. We may prefer to think of things in terms of comparisons to "A" because they occupy the same inertial state as we do, but all three are equally valid. Matt Deres (talk) 13:31, 23 October 2016 (UTC)[reply]

Each person actually has an age, not just various ages as measured by other travellers. If they carried a reliable clock with them, it has a specific time on it at the end. So there is no paradox in relative differences in ages; they should all work out right. The specific ages vary due to acceleration as described above. Wnt (talk) 23:19, 23 October 2016 (UTC)[reply]

I didn’t include many things in order to keep the question short as i presumed that it was understandable from pundits pov. Since everything is ideal therefore B and C are also traveling in the ideal rocket ship. Their rocket ships can accelerate up to their desired speed within second or minute in the time frame of A. So I think acceleration or declaration should not be the problem while calculating the ages. Regarding “Right”

1. B and C have disagreement on the age as well as physical appearance of A

2. A and B have disagreement on the age as well as physical appearance of C

3. C and A have disagreement on the age as well as physical appearance of B

Although we can add infinite number of clowns of the aforementioned leader to the scenario but for simplicity, 96 clowns are sufficient to understand if it is difficult to guess who is right on the age as well as the physical appearance of A, B and C. Clown# 96 stays on an asteroid while the rest take off at the same time with the following speeds relative to Clown#96, in the same direction for their long synchronized space journey. Assume each 10 years old at the time of departure. All 95 clowns gone for 90 years relative to clown 96. Afterward, 1 to 95 return home at the same time and reunited with clown 96 on an asteroid.

Speed of clown 1 is 0.01c , 2 is 0.02c, 3 is 0.03c, 4 is 0.04 c, ..., 10 is 0.1c, ......, 20 is 0.2c, ......, 90 is 0.9c, ....,95 is 0.95c

Again: One clown can have only one age and one physical appearance therefore who would be right on the age as well as the physical appearance of 96 clowns.

Make the above triplet paradox quadruple

Our solar system revolves around another celestial mass of our galaxy. Assume D the fourth brother / sister of aforementioned A, B and C is on this celestial mass. Since D experienced no time dilation so D finds B and C aged at the same rate as A via his special binocular. D is in disagreement with A, B, and C.2001:56A:739C:6D00:D77:CB3B:5A2B:EBDD (talk) 03:51, 24 October 2016 (UTC)eek[reply]

If each observer takes into account general relativity as well as what you call the "time dilation" of special relativity, then there is no paradox. When they finally meet up, your brothers, sisters or clowns are all observed to be different ages (as measured by their biological deterioration or by the accurate clock that each has carried), but each correctly calculates the age of each of the others when they take into account everything that has happened. Dbfirs 09:51, 24 October 2016 (UTC)[reply]

Defining the Kg in terms of (Atmospheric) Pressure

There seem to be many attempts at redefining the value of the kilogram, especially since it remained the only SI unit still dependable upon a physical artifact. Are there any practical reasons for trying to (re)define the kilogram in terms of atmospheric pressure, or height of column of mercury under specific temperature and gravity conditions (such as, for instance, [re]defining the pressure exercised by a column of mercury 3⁄4 m tall at 0°C and standard gravity as 10⁵ N exactly) ? I ask this because I don't know how practically feasible it would be to extract mass from pressure, rather than the other way around. — 79.113.203.205 (talk) 04:23, 23 October 2016 (UTC)[reply]

It is not likely to be feasible, because atmospheric pressure changes all the time, so how do you define a standard atmosphere? You suggest the height of a mercury column, but not only does gravity vary from place to place on the earth, it also varies with time, depending on the tide, and how much water is on the soil. It would be simpler for you if you tried to set a kilogram by the mass of mercury in a cubic meter. But even this precise value will depend on temperature, atmospheric pressure, isotopic composition (dependent on mine site and processing), amount of noise and motion in the liquid, electromagnetic fields present, number of cosmic rays impacting, mass of the neutrino etc etc. Graeme Bartlett (talk) 05:17, 23 October 2016 (UTC)[reply]

So what you're saying is that, although we do have a precise theoretical value for standard gravity, actually achieving that exact value with great accuracy, even in a laboratory setting, is —from a purely practical perspective— unfeasible ? So much so, that we're back to square one, only this time with mercury instead of Vienna Standard Mean Ocean Water ? — 79.113.203.205 (talk) 06:49, 23 October 2016 (UTC)[reply]

I'm not sure what exactly you're trying to get at with your question. As far as I know, the desired end goal is to define the kilogram, and all the SI base units, in terms of invariant physical constants. That way no one has to worry about their calibration standard varying with the environment. See Proposed redefinition of SI base units. --47.138.165.200 (talk) 09:26, 23 October 2016 (UTC)[reply]

Their desired goal is to rationalize all/many fundamental physical constants... which would make some sense if they would be nice and round, such as in the case of c ≈ 3·10⁸ ⁠ms⁠; unfortunately, this is not the case, so... For purely aesthetic reasons, I hope they fail. :-) — 79.113.203.205 (talk) 10:28, 23 October 2016 (UTC)[reply]

Seems completely the wrong way, IMHO. Firstly it's technically difficult - you simply can't do this by using "the atmosphere" as a standard, you'd have to construct and calibrate a simulated standard atmosphere.

Secondly the atmosphere's standardisation is based on pressure, which is based on force, thus on mass. So the standard conditions themselves are recursively self referential. If you redesigned the whole of metrology so that pressure became a fundamental unit, then you would no longer be trying to make a mass standard, you'd want to make a pressure standard instead.

Thirdly, the movement in metrology is to simplify the definitions of standards in terms of the fundamental unit they're based upon. So the intention is to supersede the platinum mass standard, defined through its weight, and replace it with a silicon sphere, based on geometry and crystalline properties. Andy Dingley (talk) 09:52, 23 October 2016 (UTC)[reply]

No, they aren't. We have a fixed height of 3⁄4 m; a specific substance, mercury; a specific time unit, the second, used to measure local gravitational acceleration and compare it to the exact value 9.80665 m⁄s². Mass times gravitational acceleration yields force, which, when distributed over a specific unit of surface (the thickness of the mercury tube), gives pressure. We then `baptize` this pressure with the name 0.1 mega Pascal, and then use Pa = kg·m^-1·s^-2 to define the kilogram. Somewhat forced, perhaps, but definitely not convoluted. (Unless I'm missing something). — 79.113.203.205 (talk) 10:28, 23 October 2016 (UTC)[reply]

So, if I understand correctly, you aren't really trying to define an "atmosphere" so much as you are trying to define the kg in terms of the weight of a column of mercury of known height? Once you dispense with the distractions, this would seem equivalent to simply weighting a known amount of mercury and adjusting for local gravitational acceleration. To be an improvement over current methods one would need at least ~1 in 100 million precision in the purity of the mercury, your ability to measure its volume, and your ability to correct for deviations in local gravity. All of that seems impractical while offering no obvious benefits compared to the current approach of using an arbitrary physical artifact. Dragons flight (talk) 14:57, 23 October 2016 (UTC)[reply]

Defining the kilogramme in terms of pressure is actually a fairly good idea, as I see it; the trick is not to use atmospheric pressure (which, as has been noted above numerous times, highly variable), but rather some pressure the value of which is completely invariant, such as the pressure at the triple point of a pure substance, or the critical pressure of a pure substance. For instance, the vapour–He-I–He-II triple point of helium-4 (which is actually one of four triple points for ⁴He—see the table in triple point) has a pressure of 5.048 kilopascals (0.04982 atmospheres); if one set the pressure for this triple point at exactly 5.048 kPa, one could then define the newton in terms of the pascal and the metre, and, then, in turn, define the kilogramme in terms of the newton, the metre, and the second, totally eliminating the need for the International Prototype Kilogramme, which could then be consigned to a museum as a historical artifact, just like the International Prototype Metre has been. Or, if one desired, one could take the critical pressure of oxygen (5.043 megapascals), define it as exactly 5.043 MPa, and use that to define the newton, and, by extension, the kilogramme. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 16:02, 23 October 2016 (UTC)[reply]

Do I remember rightly that there's an approximate relationship between length, mass, and volume? I was thinking that the original design was for a cubic decimetre to be a litre, and a litre of water to have a mass of a kilogramme. Of course the numbers have been redefined over the centuries, but I don't see a reason why they can't define a kilogramme to be the mass of a litre (or a slightly different fraction thereof, to keep the current mass unchanged) of water at a certain temperature and pressure, with the litre's definition to be the volume of a cubic decimetre (or a slightly different fraction thereof, to keep the current volume unchanged). We already have the metre being defined in terms of the speed of light during a specific period of time, and time being defined in terms of how long it takes for a specific atom to produce a specific number of oscillations. Presumably they already would have done this kind of definition if it were as simple as I'm suggesting, so where have I gone wrong? Nyttend (talk) 23:34, 23 October 2016 (UTC)[reply]

The original definition would have been like that, but it has the same problems as the mercury standard. Can you get the water 100.0000000% pure? Can you avoid water evaporating in your weight comparison? The density of water changes with air pressure, temperature, and other disturbances too, so it is not such a practical standard. Graeme Bartlett (talk) 01:51, 24 October 2016 (UTC)[reply]

One of the fundamental reasons why the SI was even introduced in the first place is reproducibility, since -without it- we are back to medieval times. If you cannot tell another person from the other side of the planet how to obtain the unit for themselves, without physically transporting some random artifact, then it has all been in vain. — 79.113.203.205 (talk) 05:20, 24 October 2016 (UTC)[reply]

Feynman Lectures. Lecture 33. Formula 33.2 [19]

${\frac {A\cos \,(i-r)}{a}}={\frac {-1}{-1}}$
I don't understand why does Feynman set aside reflected wave, deriving the formula. He says "since the two amplitudes on the left side of Eq. (33.2) each produce the wave of amplitude −1.". Even geometrically it is not true PNG dwg.
Formula must be next:
${\tfrac {A\cos ^{2}\,(i-r)+B\cdot cos^{2}(\pi -2i)}{a+b}}={\tfrac {-1}{-1}}$

Username160611000000 (talk) 12:22, 23 October 2016 (UTC)[reply]

Later Feynman says : Quote
It is possible to go on with arguments of this nature and deduce that b is real. To prove this, one must consider a case where light is coming from both sides of the glass surface at the same time, a situation not easy to arrange experimentally, but fun to analyze theoretically. If we analyze this general case, we can prove that b must be real, and therefore, in fact, that b=±sin(i−r)/sin(i+r). It is even possible to determine the sign by considering the case of a very, very thin layer in which there is reflection from the front and from the back surfaces, and calculating how much light is reflected. We know how much light should be reflected by a thin layer, because we know how much current is generated, and we have even worked out the fields produced by such currents.
Unquote
I do not recall that Feynman ever showed the formula for current. It seems he uses 31.17 to show that field which is generated by glass has inverse sign of source field. But I can't understand why should we use a case when light is reflected from both sides of the glass plate? And second, why should we prove that $b$ is real value? ${\tfrac {\sin ^{2}\,(i-r)}{\sin ^{2}\,(i+r)}}$ is real.

Username160611000000 (talk) 17:51, 23 October 2016 (UTC)[reply]

Earth ocean rifts total gas output

Is there a source that provides Earth's ocean rifts total gas outputs to the oceans and to Earth's atmosphere? Terry D Welander (talk) 18:35, 23 October 2016 (UTC) [Redacted] — Preceding unsigned comment added by 173.21.166.135 (talk) 18:22, 23 October 2016 (UTC)[reply]

I don't know about total gas output, but this paper from 1998 gives an estimate for CO2. This 2013 paper updates the result (on overall emissions it's mostly narrowing the margin of error). The newer estimate is around 7-8x10¹¹ mol/year, or (unless my math is off) around 35 megatonnes. For comparison, human emissions are around 29 gigatonnes/year. --Stephan Schulz (talk) 20:42, 23 October 2016 (UTC)[reply]

Storm surge

If the Americas were pushed out to sea about how fast would the land have to move to repeat (more or less) Hurricane Sandy's surge in New York Harbor? With several minutes of acceleration time. How long would it take the new sea level to reach equilibrium? Would a few minutes acceleration time be enough for it to be more like a surge than a tsunami? Yes, yes the power to cut a continent off the Earth and move it and keep it from sinking or causing earthquakes is beyond ludicrous. I just wonder about the wrong frame of reference where the land moves instead of the water. Sagittarian Milky Way (talk) 19:15, 23 October 2016 (UTC)[reply]

You mean like if the Americas were on gigantic pontoons? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:30, 23 October 2016 (UTC)[reply]

Wouldn't pontoons affect the sloshing? Cut off all crust above the elevation of the continental shelf edge, turn off friction at the cut, hold it up so it doesn't sink or tilt and start moving it. Sagittarian Milky Way (talk) 21:12, 23 October 2016 (UTC)[reply]

That sounds like it's in the same league with how Will Rogers proposed to get rid of the German U-Boats in World War I: "Boil the ocean!" ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:37, 23 October 2016 (UTC)[reply]

I just want to know how fast we have to go to make a significant bow wave from Greenland to Cape Horn. Helm: let's start with 3 knots southeast. Sagittarian Milky Way (talk) 22:58, 23 October 2016 (UTC)[reply]

Orion spaceship

Does anyone happen to know what is the peak G-force that the Orion Spaceship experiences during launch and/or atmospheric reentry? 2601:646:8E01:7E0B:40E5:EEF0:65B8:D229 (talk) 23:14, 23 October 2016 (UTC)[reply]

It's a simple question of weight ratios!

So it's been established that a five-ounce bird cannot carry a one-pound coconut. But are there any aircraft (non-experimental) that can carry at this ratio, with the maximum safe weight of cargo being more than three times the manufacturer's empty weight? I note that two prominent US military cargo aircraft, the Lockheed C-5 Galaxy and the Lockheed C-130 Hercules, both have manufacturer's empty weights that are greater than their cargo capacities, so I'm guessing that any such aircraft would be much smaller, since the USAF might well not use their current aircraft if smaller aircraft existed that could carry similar amounts of freight or if similarly sized aircraft could carry much greater amounts of freight. Nyttend (talk) 23:41, 23 October 2016 (UTC)[reply]

...Probably not in the categories you're thinking about. Athough my personal reservoir of knowledge is not exhaustive, I don't know of any mainstream aircraft in the fixed-wing or rotorcraft category that would satisfy what you're looking for. Depending how you choose to define "useful load" - in aviation, we include fuel as part of that figure - you might find the weight ratio you want in the payload fractions in the rockets used for launching cargo in to space. And again, if you consider fuel as part of the useful load, then the GlobalFlyer (a one-of-a-kind experimental aircraft) or the Rutan Voyager might meet your requirement. (You might read about Burt Rutan's other aircraft for his experimental airplanes that cater to a "slightly" more mainstream audience). And of course, if you consider lighter-than-air aircraft, including airships, the cargo mass can be considerably greater than the aircraft mass.

Nimur (talk) 00:10, 24 October 2016 (UTC)[reply]

Sorry I wasn't clear. I was definitely meaning entire weight of aircraft at maximum safe load divided by manufacturer's empty weight is at least 3, so I was imagining an out-of-fuel aircraft for the first one. My idea was either a fixed-wing aircraft or a helicopter (but at least in my imagination, they don't carry as much weight for their size; their advantage is maneouvreability, not mere carrying capacity) flying in the atmosphere; I wondered about a space rocket, but in the end I was only thinking about atmosphere-restricted aircraft. I've never heard of rocket airplanes (except experimental ones), but if any rocket airplanes have ever gotten out of the experimental stage and become "normal" aircraft, they'd definitely be eligible for what I was looking for. Nyttend (talk) 01:16, 24 October 2016 (UTC)[reply]

This aircraft[20] Weighs 220 Lbs and lifts 2,423 Lbs... Also see:[21][22] --Guy Macon (talk) 01:35, 24 October 2016 (UTC)[reply]

If you are looking at max takeoff weight / empty weight, the B-52 gets somewhat close at 2.6. The Lockheed U-2 is even better at 2.8, though in that case it's almost entirely fuel and almost no cargo. Dragons flight (talk) 02:10, 24 October 2016 (UTC)[reply]

Biological Endothermic Processes 3E9 YA

I have a question about what biological endothermic reactions were used by the anaerobic organisms to capture solar energy, which could then be utilized to provide energy, three billion years ago. I haven’t found the answer in the articles that I have read so far. Two billion years ago, the planet was not that different than it is today, and photosynthesis converted water and carbon dioxide into glucose with the release of diatomic oxygen. The development of photosynthesis by the cyanobacteria, approximately 2.5 billion years ago, resulted in the great oxygenation event or oxygen catastrophe, and aerobic life became dominant. What endothermic reactions captured solar energy, presumably with less captured energy, prior to photosynthesis? I am assuming that there were endothermic processes capturing solar energy, because otherwise life would have been running entirely on leftover energy. Were the early endothermic reactions inorganic? Regardless of whether they were organic or inorganic, do they still occur in the modern oxygen-based world? Robert McClenon (talk) 03:15, 24 October 2016 (UTC)[reply]

Your assumption is incorrect. Organisms at places such as hydrothermal vents are "running entirely on leftover energy". There is no rule that says life must ultimately derive its energy from the Sun. We've found extremophiles in many habitats without access to sunlight. This has excited a lot of people about the prospects for life elsewhere in the universe. A place like Europa might have life in the subsurface ocean even though there's no sunlight available. There's a lot of "leftover energy" beneath a planet or large moon's surface. (Although, a substantial portion of this energy is produced by radioactive decay, which might not count as "leftover" based on your definition.) --47.138.165.200 (talk) 08:00, 24 October 2016 (UTC)[reply]

Primary producers are generally divided between photoautotrophs, which rely on the sun, and chemoautotrophs that derive energy and growth by acting on inorganic chemicals present in the environment. Such compounds are abundant at locations like hydrothermal vents, but can be found in low quantities nearly everywhere. Many chemolithotrophs consume compounds derived from minerals exposed at the Earth's surface. Other chemotrophs consume compounds like methane, which was believed to be abundant in the pre-oxic atmosphere. Yet other chemotrophs can create methane by consuming carbon dioxide and hydrogen. There are many metabolic pathways capable of capturing energy from inorganic compounds. In general such pathways usually offer less abundant energy than photosynthesis, but many forms of life can survive without a connection to the sun. Dragons flight (talk) 09:48, 24 October 2016 (UTC)[reply]

A little sympathy is in order for the anaerobic bacteria. It was their planet once. Robert McClenon (talk) 03:15, 24 October 2016 (UTC)[reply]

[1] Taubenberger, Jeffery K; Hultin, Johan V; Morens, David M (1 January 2007). "Discovery and characterization of the 1918 pandemic influenza virus in historical context". Antiviral therapy. 12 (4 Pt B): 581–591. ISSN 1359-6535. PMC 2391305.

[2] Stone, R. (15 March 2002). "PUBLIC HEALTH: Is Live Smallpox Lurking in the Arctic?". Science. 295 (5562): 2002–2002. doi:10.1126/science.295.5562.2002.

[1]

[2]