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January 6

Gears in gym equipment

The most common weight lifting machines around me just consist of a set of metal plates (can be configured) attached to a cable that go through two pulleys. I know that alternative ways of creating resistance for exercising exist, like pneumatic, elastics, and so on. I suppose these are not as resilient and low on maintenance as a simple block of metal plates with a cable attached. I wonder, couldn't they just make a machine with one weight and a set of gears to add more resistance? I imagine you could also use a level to alter the resistance, but that seem more of clumsy solution. --31.4.128.9 (talk) 08:20, 6 January 2020 (UTC)[reply]

They could, but a possible downside is that people like to know how much weight they are lifting, and the usual arrangement makes that obvious. Alansplodge (talk) 13:59, 6 January 2020 (UTC)[reply]

What's "resistance"? Are you after a large force on a small movement, or a lower force over a long distance? Weights have several advantages: they're simple, reliable and cheap. They also provide a high force, and they provide a constant force. Most spring devices will change force over their travel. It's also easy (with a pin in a stack) to change the force from the same machine, keeping the same overall distance. It's also easy to assemble a weight-based machine, whilst a spring machine might need an assembly jig and carry a risk of finger injury.

For high force devices, most use weights. Some use the operator's own weight - a common design for outdoor park exercise machines is based on lifting the user's own weight, which is usefully self-calibrating for a wide range of users, without needing to adjust anything. These tend to use levers as force adjusters, as the most long-term reliable machine. A few machines use springs or hydraulics, but these are more complicated and have maintenance issues. Elastic (i.e. polymer elastomers) is rarely used (small home-use devices), as it has lifetime issues and a sudden snap is a real problem to design for in a "safe" machine.

For higher forces, a pulley system is more common than gears. It stands up better to wear and exercise equipment is in a very litigious market, where reliability is important. There's sometimes a need to offer a longer movement (some horizontal pulls) and pulleys can do that too - otherwise it's easier to just make more weight go up higher.

For aerobic exercise rather than strength, the load was usually an air fan, a viscous drag or a magnetic eddy current in an aluminium disc. Nowadays though, machines are computer controlled, so active electrical devices (motors) are used, even though they're expensive, complicated and need a power source, just because they're more easily controlled. Andy Dingley (talk) 14:51, 6 January 2020 (UTC)[reply]

A convict in Victorian Britain might find exercise machines crank and treadmill provided for his benefit. DroneB (talk) 16:25, 6 January 2020 (UTC)[reply]

Neither of those were 'exercise' machines. They (deliberately) weren't particularly hard labour, they were mostly boring. Where convicts did actual hard labour (and Dartmoor was one of the few UK prisons where this was the classically hard-working stone-breaking work) they had to be fed better, or else they starved and died. In the typical prisons, the work was tedious but not so energetic, and so the food costs were lower. Andy Dingley (talk) 16:42, 6 January 2020 (UTC)[reply]

Torture and Democracy by Darius Rejali (p. 301) says: 'Nineteenth-century British prisons and reformatories preferred exhaustion exercises. Guards required prisoners to perform shifts on various devices, notably the treadmill (1817) and the crank (1840). As one ascended the wheel, the previous step slid away. It exhausted the strongest of men in fifteen minutes. Turning the crank required turning a handle twenty revolutions a minute, for a total often thousand revolutions in 8.5 hours. “No human being, whether adult or juvenile, could continue to perform such an amount of labour of this kind for several consecutive days, especially on a prison diet, without suffering much and wasting greatly".'

The quote is from Report of the Commissioners Appointed to Inquire Into the Condition and Treatment of the Prisoners Confined in Birmingham Borough Prison, and the Conduct, Management, and Discipline of the Said Prison (1854) p. vii. Alansplodge (talk) 18:02, 6 January 2020 (UTC)[reply]

"Victorian" goes on a long while after that though, and these were falling from use. I think the crank stayed for a long time, but it was specifically punitive (they still have one in Lincoln Castle). Andy Dingley (talk) 18:13, 6 January 2020 (UTC)[reply]

We have both a section of a treadmill, and a crank, in Ripon Prison and Police Museum. --ColinFine (talk) 19:10, 7 January 2020 (UTC)[reply]

Other sources of resistance are flywheels and generators. The latter have the advantage of offering a "reward" such as powering an electric fan. NonmalignedNations (talk) 06:22, 8 January 2020 (UTC)[reply]

Thought experiment: Star with mass in the Brown dwarf mass range with a lot of fissionable elements

Could a brown dwarf with enough Uranium or Potassium 40 shine above its weight class? Perhaps it could do normal hydrogen fusion, instead of deuterium fusion?144.35.45.50 (talk) 23:29, 6 January 2020 (UTC)[reply]

If it performed hydrogen fusion, it would by (current) definition not be a brown dwarf, but a low-mass red dwarf. The two catagories are not strictly segregated by mass (or any other single criterion), and may overlap in characteristics depending which one(s) one chooses to apply. {The poster formerly known as 87.81.230.195} 90.204.182.54 (talk) 23:55, 6 January 2020 (UTC)[reply]

Right, but beyond the question of classification, could such a star exist?Thanks. Rich (talk) 00:43, 7 January 2020 (UTC)[reply]

A natural nuclear reactor could easily exist if the concentration of uranium was high. Of course this is unlikely in a uniformly mixed gaseous body. Perhaps a star formed from binary neutron star merger hypernova output could be highly radioactive and hot, also containing plutonium and thorium. A lot of potassium would also make the body hot. Graeme Bartlett (talk) 03:06, 7 January 2020 (UTC)[reply]

Do you think it would require a fission chain reaction, rather than just many isolated fissions? The fissions here on earth produce a lot of heat.Rich (talk) 04:40, 7 January 2020 (UTC)[reply]

To explain what I meant, suppose a brown dwarf had a mass of 50 Jupiters, and for some bizarre reason, maybe advanced alien tech, that one of those 50 jupiter masses was entirely Pottasium 40. Then isolated disentegrations should provide much much more than just the heat of 32 Earths, because although jupiter is a mass of around 32 earths, fissionable atoms are a small fraction of theearths mass.Rich (talk) 04:51, 7 January 2020 (UTC)[reply]

This could actually make the star a more massive brown dwarf, possibly over the "typical" mass limit for a brown dwarf. A main sequence star is a ball of stuff in hydrostatic equilibrium; its gravity constantly tries to collapse it more, while the fusion in the core generates heat and tries to expand the star, and these two forces maintain a constant tug-of-war as long as there's sufficient fuel in the core. If there's another source of heat, this expands the star as well, opposing the gravitational collapse and therefore reducing the temperature and pressure in the core, possibly below that necessary for the p–p chain. --47.146.63.87 (talk) 07:47, 7 January 2020 (UTC)[reply]

Interesting!Rich (talk) 20:53, 7 January 2020 (UTC)[reply]

To stretch your noodle some more, there are various hypothetical stars supported against collapse by something other than heat produced by fusion. A couple are already known to exist: white dwarfs and neutron stars are supported by electron and neutron degeneracy pressure, respectively. A Thorne–Żytkow object would be a red giant with a neutron star as its core. Quasi-stars may have been some of the first stars in the universe, with black holes as their cores, supported against collapse by the radiation and heat generated as the black holes accreted matter. --47.146.63.87 (talk) 06:34, 10 January 2020 (UTC)[reply]

Fascinatinging!Rich (talk) 01:50, 11 January 2020 (UTC)[reply]

(edit conflict) Weight is not really a thing when talking about stars; scientists talk about them in terms of mass, which doesn't vary based on gravitational effects. If a star has enough mass to start the proton–proton chain, it's a red dwarf by definition, as noted above. A star with high metallicity will be denser than a low-metallicity star of the same mass, because the "metals" are denser and thus pack more mass into a smaller volume. This is an example of human intuition short-circuiting. We intuitively think of weight and mass as the same thing, because we think about things in our everyday existence under the influence of Earth's gravity. But stars are ginormous things that gravitate under their own gravitational fields. The primary thing that determines a star's character is its mass, because its mass is what produces its gravitational field. --47.146.63.87 (talk) 04:59, 7 January 2020 (UTC)[reply]

I don’t think any of the posters, including myself, have in any way confused mass with weight. You’ve misunderstood what’s been said.Rich (talk) 07:07, 7 January 2020 (UTC)[reply]

The OP, who 47 replied to did in fact use "weight class" in the question and "mass range" in the heading. I don't know if the OP is actually confused about the difference between weight and mass, but although the term weight is often used to refer to mass in a colloquial sense, I'd agree with 47 that this is one case where it important to appreciate the difference. Nil Einne (talk) 14:38, 7 January 2020 (UTC)[reply]

This is my bad, im the OP. I forgot i used that idiom/sports cliche. “Punching(or shining or performing) out of one’s weight class often does not, now, refer to weight and boxing anymore, for example if a usually poor student outstudies and outscores the class brain on an exam, or if a slow sprinter gets a fast time on the 400 meters due to high anaerobic endurance, it’s said they are performing out of their weight class.Rich (talk) 20:51, 7 January 2020 (UTC)[reply]

To clarify the question/premise: ⁴⁰K isn't a fissionable nuclide - instead it can decay by ordinary beta decay as well as electron capture and positron emission. Natural uranium and thorium isotopes show [[spontaneous fission], but at a very low rate - much more heat will be generated by the alpha decay of these elements, combined with decays of the daughter nuclides.

Anyway, you might be interested in a curious object which seems to contain short-lived actinides: Przybylski's Star

Icek~enwiki (talk) 22:30, 12 January 2020 (UTC)[reply]

January 7

relation of human-fungi for antibiotics

In biology, we have many types of relations between two organisms and more (i.g. commensalism, symbiosis etc.). My question is what's called the relation / way of people to take or produce antibiotics by fungi? 93.126.116.89 (talk) 00:11, 7 January 2020 (UTC)[reply]

It is called Medicinal fungi and Wikipedia has an article about it. --Jayron 32 12:07, 7 January 2020 (UTC)[reply]

Thank you for your comment, but it isn't my question:). I asked about the relation (I gave a couple of examples for relations in biology: commensalism, symbiosis). 93.126.116.89 (talk) 21:17, 7 January 2020 (UTC)[reply]

Typically the fungus is destroyed in the process of consuming it. You would call it mycophagy. A non-human animal that consumes another organism for medicinal purpose could be said to be engaging in zoopharmacognosy. Someguy1221 (talk) 21:57, 7 January 2020 (UTC)[reply]

Why we can't call it Amensalism? see here for example. 93.126.116.89 (talk) 21:21, 8 January 2020 (UTC)[reply]

If a person or other animal is gaining a health benefit from the interaction, it's not amenalism, which is neutral to one party and detrimental to the other. Someguy1221 (talk) 01:52, 9 January 2020 (UTC)[reply]

Then it should be parasitism? we are parasite for those fungi?93.126.116.89 (talk) 15:53, 9 January 2020 (UTC)[reply]

Good question. Fungi are often but not always destroyed in the process, so possibly the same as obtaining milk from cows or honey from bees, but anyway the same as obtaining meat from cattle, flour from wheat or wine from grapes?

This would be parasitism but I think we call it differently when we eat an apple and when a caterpillar eats the same apple. 2003:F5:6F05:EC00:CD93:6D9C:AE97:D83B (talk) 14:06, 10 January 2020 (UTC) Marco Pagliero Berlin[reply]

January 8

Which of "geometric algebra" or "algebraic geometry" proceeds the other.

Wow! sushi (talk) 05:08, 8 January 2020 (UTC)[reply]

(we don't have so much time...) _ I need to confess , I am multi-personalities.

Wow! sushi (talk) 05:12, 8 January 2020 (UTC)[reply]

Geometric algebra#History 1844

Algebraic geometry#History 16th Century? Graeme Bartlett (talk) 05:50, 8 January 2020 (UTC)[reply]

Insect identification

Hello, What is this insect called? I found it in Mizoram, India. There are shells on the body and the trail illuminates in the dark.

Sandeshkumar M. 11:19, 8 January 2020 (UTC)

Are you sure this is an insect? Check the underside for number of legs. It has the same number of segments as a woodlouse. Graeme Bartlett (talk) 09:50, 8 January 2020 (UTC)[reply]

I don't really know what it is. An insect or something else. I've uploaded another image of the creature.

Sandeshkumar M. 11:28, 8 January 2020 (UTC) (talk)

To help accurate identification include -

Something to show scale: ideally that would be a ruler with millimetre graduations. A picture of the bottom of the organism. A white background for the picture - it helps to give a better idea of the colour of the organism. A picture of the bioluminescence - this would be in an ideal world. A picture of the place you found it - to give an idea of habitat. A general name like Mizoram is useful - it narrows things down. But was it in woodland or human settlement. I appreciate this is a lot of information, but accurate identification is aided by this kind of information. There are places in India where bioluminescence is common. For Mizoram, that seems to be plant based rather than animal so more information about the animal is really needed to identify it correctly.

Having said that: it does look quite like a woodlice (and definitely an isopod). But I only counted eleven obvious segments - there could be 14 which is indicative of a woodlouse - a picture of the rear end from above would help to clarify that. There appear to only be three pairs of legs - woodlouse have seven pairs of legs (they can vary in size, so only seeing three pairs might mean the others are hidden). — Preceding unsigned comment added by Hongnang (talk • contribs) 12:55, 8 January 2020 (UTC)[reply]

Isopod link. NonmalignedNations (talk) 16:42, 8 January 2020 (UTC)[reply]

This might actually be a firefly larva. Graeme Bartlett (talk) 00:06, 9 January 2020 (UTC)[reply]

Yes I also think this is a bioluminescent beatle larva. Just as it is said that there are 11 segments on its back and and the last two segments have white patches which illuminates in dark.

And thanks for all your help. But don't know which species.

Sandeshkumar M. 02:14, 9 January 2020 (UTC)

Probably Firefly Larva from India says that identifying a beetle from its larva is "difficult if not impossible" but goes on to say that "if you watch it eat a snail or slug, it is definitely a Firefly larva". Alansplodge (talk) 17:56, 9 January 2020 (UTC)[reply]

Human Predation

When a predator is removed from the food chain it is often seen that there is an overpopulation of another species. The most well-known example I can think of at present (which is not the same) is the Cane Toad in Australia, where without a predator, they have bread to enormous population sizes causing widespread destruction. Further to this, if predation on a species takes place the food item tends to populate to make up for the loss and similarly if a food source reduces the number of predators reduces too. To expand on this concept, if my reserve has 10,000 impala and I have 100 lions, (10:10,000)… if the lions eat 2,000 impala, the impala will generally have about 2,000 offspring during the next breading cycle, and the numbers (presuming they are evenly matched, lions to impala and assuming there are no other animals [work with me here people]) In the same manner, if I hunt 9,000 of my impala, my lions will die off until I have only 10 (1,000:10). Nature ensures there is an equilibrium, if all of the additional environmental factors are left in situ and allowed to run their course. What has been removed from the ecological chain to allow for the human race to overpopulate to such a degree as to cause the now seen climatic chaos. How was this element removed? Thanks. Anton 81.131.40.58 (talk) 15:56, 8 January 2020 (UTC)[reply]

Are you looking for a book on basic ecology? Humans fill a niche in the local and the global ecosystems, but your description of simplified replacement of one species by another... well, that is just overly simplified. Start with our Wikipedia article on ecological niche, human evolution, and so on... Nimur (talk) 16:15, 8 January 2020 (UTC)[reply]

Technology has allowed humans to expand from one ecological niche to many others. Chimpanzees, by comparison, only inhabit small portions of Africa. One very simple technology humans use is clothing, allowing us to live in far different climates, such as the arctic. And predation doesn't limit human numbers, since humans are more likely to kill the predators, such as sharks or lions. NonmalignedNations (talk) 16:37, 8 January 2020 (UTC)[reply]

If you hunt 9,000 of the impala and lions eat 2,000 a season, the lions will likely eat all the rest in a few generations and then you'll have no impala and no lions, or the lions will eat enough that they starve to death the next generation and you'll have problems when the impala population rebounds back above 10,000. Even if they both manage to survive, you'll have an increased risk of extinction of either species due to the ensuing genetic bottlenecks. Equilibrium is ensured for small changes only. 89.172.38.145 (talk) 06:38, 10 January 2020 (UTC)[reply]

you assume that the limiting factor to human population growth was predation, when it might not have been (my impression is it almost certainly wasn't except perhaps in the deepest of pre-history.) The human population growth and overpopulation (if any) is usually credited to things like farming, industrialization, hygiene etc. Aecho6Ee (talk) 11:36, 12 January 2020 (UTC)[reply]

Where’s Greta when you need her?

Linked to the previous question and brought to my attention recently by a much younger person, was that the current environmental crisis should resolve itself. The rationale provided for this argument was that all of the fossil fuels and Co2 gasses being put into the atmosphere are all from earth and have been part of the ecology and part of the overall cycle of minerals etc. within the planetary system. I was not able to counter this point, as my questions clearly show I am not a scientist or scientifically minded. Please would you help me to understand why this theory does not hold water, as I am sure that it doesn’t but can’t explain why. Thanks. Anton 81.131.40.58 (talk) 15:57, 8 January 2020 (UTC)[reply]

Review the Wikipedia article entitled tipping points in the climate system, which is written for a general audience but cites detailed technical sources for the interested reader.

Some complicated systems are self-stabilizing; some are subject to instability. Scientists have reason to believe that some aspects of the Earth's climate may be undergoing an irreversible alteration that deviates from the stable "self-regulating" zone, which is one of the reasons for international concern. If you're interested in why some scientists believe such things, our article is a great introduction to the science, data, and models, that drive their concern. Nimur (talk) 16:08, 8 January 2020 (UTC)[reply]

As for burning fossil fuels, those are burnt far faster than they accumulated, meaning we have thousands of years worth of fossil fuel produced gases all in the air at once. This leads to much higher concentrations of greenhouse gases than would naturally occur, and hence more greenhouse effect, and unnaturally higher tempertures. NonmalignedNations (talk) 16:54, 8 January 2020 (UTC)[reply]

Maybe we should all go back to using wood-burning stoves. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:59, 8 January 2020 (UTC)[reply]

Actually, pellet stoves, which burn compressed wood pellets, are looked at as a renewable heat source that is much closer to "carbon neutral." But in response to the OP, NN has the obvious and correct answer that's easier to explain than tipping points and the complications of these systems. Yes, all of this CO2 was once in the atmosphere, but not all at the same time. Even if we were to assume that all of the coal we have burned (or will burn) is from just the Pennsylvanian subperiod (a lot of the coal is from that time, but not all of it), and we take the period of industrial output to be from 1760 (the start of the Industrial Revolution, and this is generous since our output has accelerated over this time period a lot), that means we have been outputing CO2 that took nature about 24 million years to sequester in the space of 260 years. In otherwords, we are releasing CO2 into the atmosphere about 90,000 times faster than nature took it out of the atmosphere. Again, these are really rough numbers and I could be off by an order of magnitude or so, but you get the general idea. That's also just for coal, it doesn't account for oil at all. --OuroborosCobra (talk) 19:07, 8 January 2020 (UTC)[reply]

There is an obvious response to this if you understand the history of the Earth. Earth was once a ball of molten rock, so if it becomes that again, there's no problem; it'll all sort itself out. Earth was once hit by an asteroid 10 miles in diameter, so if that happens again, there's no problem; it'll all sort itself out. Earth is a big ball of rock. It's not going anywhere. The problem is we're disrupting our biosphere, which we rely on for things like food. Also, heat plus humidity means in some places it can get too hot during the day for humans to survive outdoors. Earth will "sort itself out" just fine; it's just that this might involve lots of humans dying. Or in the words of the late great George Carlin: "The planet is fine. The people are fucked!" --47.146.63.87 (talk) 22:05, 8 January 2020 (UTC)[reply]

Nature always wins. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:08, 9 January 2020 (UTC)[reply]

"Civilization exists by geological consent, subject to change without notice." --Will Durant, quoted by --Khajidha (talk) 16:35, 9 January 2020 (UTC)[reply]

Help me identify raptor

The raptor above was photographed by me today, from the window of my office on the 26th floor of an office building in downtown, Brooklyn, NY. By no means is this his or her first visit; this raptor swings by approximately weekly recently, and he has been coming to my ledge at various times for a few years. I was wondering if someone with some expertise can definitively identify the species (hopefully my picture is clear enough for that). I think it's a peregrine falcon but I am far from certain in my lay identification. Thanks--Andy-Em-Ess (talk) 18:47, 8 January 2020 (UTC)[reply]

It appears to be a Peregrine falcon. When in doubt, I consult the Peterson Field Guides appropriate to my region. Those books have comparison pictures and point to the exact most distinctive markings that help disambiguate and distinguish one bird from another. Nimur (talk) 20:49, 8 January 2020 (UTC)[reply]

This report looks at Peregrines in New York. Given where you saw the bird, and the Peregrine's love of high vantage points for hunting, that identification seems almost certain. Mikenorton (talk) 09:27, 9 January 2020 (UTC)[reply]

They nest in tall buildings too; see Diary of an urban peregrine falcon nest in Chicago – in pictures. Alansplodge (talk) 17:50, 9 January 2020 (UTC)[reply]

Does it have a name? May I Suggest Mr Chubby-cheeks? Thanks. Anton 81.131.40.58 (talk) 15:39, 9 January 2020 (UTC)[reply]

January 9

Minimising water wastage

I may have asked a related question some years ago, but in any case let me rephrase it.

When I turn my shower on, there's a short lag while the hot water reaches me. If my aim is to minimise water wastage, is it best to have the volume turned to high, or low, or some optimal point in between, or does it make zero difference what I do? -- Jack of Oz ^{[pleasantries]} 19:07, 9 January 2020 (UTC)[reply]

I'm sure the volume makes a negligible difference. I start at maximum heat and adjust as it goes to reduce water waste. Your best option would probably be to install a different kind of water heater that doesn't have lag due to pipes. One behind the showerhead rather than in the cellar or what have you. These exist, I don't remember the name for them. But: one is unlikely to affect much of anything by their shower duration. One's cumulative water use depends much more heavily on the products and foods they consume, and the companies they patronize. The shift of the burden of environmental damage from corporations to individuals is a bamboozle. Temerarius (talk) 19:50, 9 January 2020 (UTC)[reply]

As a measure to reduce an individual's total cumulative water use Temarius is doubtless correct. But JackofOz did not raise the issue of environmental damage, and may (as I do) inhabit a domestic property whose water use is metered and charged by volume, in which case measures to reduce the water usage of that property can impact significantly on the wallet of the person who pays its water bill.

My domestic supplier (Southern Water, in the UK) includes in its bills a table of daily water use for "typical" households of from one to six persons, viz: 6 - 548 litres, 5 - 493, 4 - 438, 3 - 370, 2 - 274, 1 - 178. My most recent bill, covering April–September inclusive 2019, shows my (single-person household) usage as 22 litres/day, around 12% of "typical", so clearly there is considerable scope for reducing one's domestic water usage (and resultant bill).

Regarding JackofOz's hot-water lag period problem, one possible measure might be to hold a bucket under the shower head until it begins to flow warm, and re-use the collected water for some other purpose, such as watering garden plants or filling the WC cistern. {The poster formerly known as 87.81.230.195} 90.204.182.54 (talk) 20:53, 9 January 2020 (UTC)[reply]

If taking a bath, the too cold water that comes out first can be mixed with the too hot water that comes out later to produce just right water, with no waste. However, the cold will tend to stay at the bottom and hot at the top, so mixing will take some effort. NonmalignedNations (talk) 22:19, 9 January 2020 (UTC)[reply]

It's about 20 seconds typically at full blast, that's 3 or 4 litres. It makes no difference volume-wise whether you open the tap fully or not, you need to expel all that cold water between the hot water source and the shower head. I'm on rainwater, so towards the end of the summer I have to get used to starting my showers icy cold! Greglocock (talk) 22:46, 9 January 2020 (UTC)[reply]

It might make a difference volume-wise depending on the heat capacity of the pipe (thermal mass, insulation in cold spaces, etc) because it's not just "hot pushes cold" (volume is the pipe volume), but the water cools down as it heats the pipe along the way until the pipe is up to equilibrium temperature. @Temerarius: seems to be thinking of a tankless water heater. DMacks (talk) 04:06, 10 January 2020 (UTC)[reply]

I am familiar with the predicament described by JackofOz. Some of the hot-water taps in my house are a long way from the water heater (gas-fired.) During the protracted period of drought and water restrictions in 2003 everyone in my house got into the habit of putting an empty milk carton under the hot tap and filling it until the hot water arrives. Later, the milk carton is emptied into a watering can for use on the garden. It proved to be such a good idea that we keep doing it, even though the drought and water restrictions ended after 4 or 5 years. Dolphin (t) 04:55, 10 January 2020 (UTC)[reply]

Collect the initial cold water in a bucket and use it to flush the lavatory.--Shantavira|^{feed me} 09:43, 10 January 2020 (UTC)[reply]

In luxury yachts there is the option for instant hot water as the hot water pipe circulates continuously to the boiler, called hot water circulation. That would solve your problem, but it is probably not a cost-saver Rmvandijk (talk) 10:02, 10 January 2020 (UTC)[reply]

If the shower is used in a morning shit-shower-shave routine, the hot water lag will waste less water if the toilet can be flushed from the hot water supply. (A special plumbing arrangement would be needed, possibly as a third option on a Dual flush toilet).

Often hot water is supplied from a tank where it is heated to a higher temperature than used for showering. The water loss during the delay in the pipe before tolerably warm water flows in the shower can be minimised by starting with 100% hot / 0% cold mixer tap setting. To control this manually risks scalding but Thermostatic mixing valves can be fitted to achieve it.

The "Navy shower" method conserves water and energy by turning off the flow of water in the middle portion of the shower while lathering.

You may consider whether various ideas for Water recycling showers appeal.

In a space station where water is at such a premium that a Life support system may reclaim potable water from urine, Skylab had a shower for use without gravity: the user was surrounded by a curtain, water was sprayed in and then removed by a vacuum cleaner. Quora has addressed questions such as How do astronauts wash themselves in space? and How do astronauts bathe in space? How do they dispose of their waste?. DroneB (talk) 13:02, 10 January 2020 (UTC)[reply]

If you are able to and it's not already done, consider insulating your pipes. According to [1], the water will still only stay hot for about 30 minutes or so, but may still be useful especially if there are multiple people using your shower, or you take a while to lather etc with the shower off. And if you have access to the pipes and sufficient mobility, it's a relatively easy and low cost DIY task. Nil Einne (talk) 04:55, 11 January 2020 (UTC)[reply]

The insulation will have a secondary benefit. That is, it will reduce heat loss from the pipes after they've reached maximum temperature. With a long path of uninsulated pipes, you might notice that the maximum water temperature at the tap is considerably lower in winter, due to this heat loss. NonmalignedNations (talk) 14:52, 11 January 2020 (UTC)[reply]

January 10

Effects of aviation on climate change via contrails

Aviation is supposed to cause climate change not only due to CO₂ emission, but also through other mechanisms, such as forming of contrails, cirrus clouds and ozone. However, these effects are short-lived. As far as I understand, when calculating the global future effect of a flight, say for 20 years from now, one takes the effect of, for example, the cotrails formed, multiplies by their duration, and then divides by 20 years.

This seems great if I want to either calculate the average effect over the next 20 years, or if I want to see the effect of trends in global aviation.

However, ignoring the differences between day and night, summer and winter etc., if I am interested in the effect of my next flight on the climate 20 years from now, this seems like a wrong calculation: Any transient effect lasting hours, days or even a year, will most probably fade away totally by the time 20 years have passed. Thus only the CO₂ emission will actually have any effect 20 years from now.

Is this true? Thanks! Dan Gluck (talk) 17:12, 10 January 2020 (UTC)[reply]

Unless the effect isn't transient in the bulk; one flight may leave a transient amount of cloud formation which would dissipate if that were the only plane in the air. All flights together, taken as a group, are essentially permanently adding that effect to the atmosphere, because the effect never dissipates. --Jayron 32 17:41, 10 January 2020 (UTC)[reply]

Additionally, you are likely describing countering effects. Contrails and cloud formation increase the Earth's albedo, which has a local cooling effect. This could, on the short term, seemingly mask or reduce some of the warming effects of the CO2, but once the clouds and contrails dissipate, the albedo drops, and the warming effects are not masked. Your one flight will not have impact from controls and cloud formation directly during the flight in 20 years. Its carbon output might still be felt. However, even that is overly simplistic. If we stopped all industrial activity, all transportation activity, all agriculture, all aviation, etc., i.e. if we stopped all anthropogenic carbon emissions today, CO2 in 20 years might drop (possibly significantly). That is, unless we have already passed through a tipping point. It isn't the one flight or the one driving your car that's the issue in 20 years, it's the constant/increasing levels of carbon output that's the issue. To take one action and try to measure the 20 year impact ignores that the levels are a result of constant, and not transient output. --OuroborosCobra (talk) 18:22, 10 January 2020 (UTC)[reply]

Thanks for that, but you haven't really answered my question. Obviously one flight doesn't do much - it's the aggregation of flights that does. But one still may ask what is the contribution of one flight to that aggregate. The constant rather than transient effect you are referring to is due to the fact that there are flights all the time, but that is not what I've asked.

When refering to policy-making, there is not much of a difference. But When thinking about how personally I should change my behaviour in order to reduce my personal contribution to the climate change, it does matter. Dan Gluck (talk) 09:58, 11 January 2020 (UTC)[reply]

The 2007 IPCC summary cited in the article section has a positive (0.01 [0.003 to 0.03]) value for radiative forcing, but a "Low" assessed level of scientific understanding. Another source, from New Scientist[2] states On average, both thin natural cirrus clouds and contrails have a net warming effect. The discussed study is here, maybe it or one of its references may help.—eric 17:26, 11 January 2020 (UTC)[reply]

January 11

Quark Magnetic Resonance

Could an X ray laser, or someday a gamma ray laser, be applied to a bunch of protons, and although xrays are probably pretty weak and long wavelengthy compared to quarks size, gradually excite the quarks inside the protons until they emit a signal? I’m thinking of an immobile grid of hydrogen ions trapped on a sheet of insulating material, and pulses of xrays shot at them at some fraction of a resonant frequency.Rich (talk) 02:07, 11 January 2020 (UTC)[reply]

This excited proton would be classified as a different particle, the
Δ⁺
. See Delta baryon for more info. Graeme Bartlett (talk) 07:14, 11 January 2020 (UTC)[reply]

If the idea is to get a signal from the quarks inside the proton, this can be done by high-energy collisions of other particles with the proton. You thought of using photons (which in a classical approximation are seen as "x-rays" of "gamma-rays"), but most convinently it is done with electrons or similar more massive particles. See Deep inelastic scattering. Dan Gluck (talk) 10:04, 11 January 2020 (UTC)[reply]

What you are talikng about is called photo-excitation of baryonic renonances. There exist a lot of them. You can also read publications: for instance this. Ruslik_Zero 17:54, 11 January 2020 (UTC)[reply]

Why don't primates live in Europe and the Middle East?

I know that humans are primates, and I know that there are a few apes on Gibraltar and in Saudi Arabia, but given that monkeys are so versatile and adaptable, why aren't there monkeys or apes living in European countries or across the Middle East? They live in hot, dry parts of Western India and in the Yemen, and they've adapted to live in cold parts of Japan, so why have they never come further north into Europe, etc. — Preceding unsigned comment added by 95.150.37.255 (talk) 17:47, 11 January 2020 (UTC)[reply]

In Europe they were wiped out by Ace Ages. Ruslik_Zero 18:07, 11 January 2020 (UTC)[reply]

There should have been more than enough time for nonhuman primates to move back into the rest of Europe and Asia since the ice ages. Thus, there must be some factor which keeps them from moving north. The obvious difference is the climate. While it gets somewhat cold in Japan, it certainly gets far colder in northern parts of Europe and Asia. The central regions of Europe and especially Asia, not having temperatures moderated by air coming off the ocean, can also suffer from extreme temperature variations. But there are certainly some regions of Europe, like southern Italy, where the climate would be acceptable to many primates. So, some other explanation is needed there, perhaps hunting from prehistoric humans or predation from animals such as dogs. NonmalignedNations (talk) 04:54, 12 January 2020 (UTC)[reply]

If it's due to human predation, another question would be why monkeys haven't been hunted to extinction in Africa, as humans originated in Africa as well.

Let's suppose the answer is that the tropical conditions in Africa just allow a higher density of monkeys while humans don't have as much of an advantage compared to cooler climates.

Then the question is, why did monkeys survive in Japan? Is 40000 years (according to History of Japan) not enough for humans to have hunted them to extinction? Icek~enwiki (talk) 15:18, 12 January 2020 (UTC)[reply]

"About 230 macaques live on the Rock of Gibraltar (=Europe). This population appears to be stable or increasing, while the North African population is declining". (article on Wikipedia). 93.126.116.89 (talk) 04:37, 12 January 2020 (UTC)[reply]

Our article on Oreopithecus, an ape that lived in Italy 7 or 8 million years ago, says that "When a land bridge broke the isolation of the Tusco-Sardinian area 6.5 million years ago, large predators such as Machairodus and Metailurus were present among the new generation of European immigrants and Oreopithecus faced quick extinction together with other endemic genera". So you can't blame us for that - it was them sabre-toothed tigers, they come over here and take our monkeys... ;-) Alansplodge (talk) 19:14, 12 January 2020 (UTC)[reply]

Although that greatly predated the extinction of other primates as RuslikZero's comment implied [3]. BTW this study [4] (news article discussion [5]) came to the conclusion that the main factor in the extinction of the European great apes was a failure to adapt to the food supply after deciduous trees replaced evergreen due to their existing dietary adaptations. Nil Einne (talk) 21:12, 12 January 2020 (UTC)[reply]

Note to the OP that as per that article and ape, barbary macaques aren't apes under the most common modern definition of the word despite barbary ape being another common name. Nil Einne (talk) 21:12, 12 January 2020 (UTC)[reply]

What in common to all vitamins B group (except for water solubility)?

I see that all vitamins B group are water soluble (but also vitamin C is). So I'm interested to know the reason that all vitamins in B groups name with the letter B. 93.126.116.89 (talk) 18:56, 11 January 2020 (UTC)[reply]

Formerly some of them had other vitamin letters. Vitamin B2 was vitamin G. Vitamin B7 was vitamin H. Vitamin B9 was vitamin M. And vitamin B3 was vitamin PP. But there is no vitamin B4 or vitamin B8. Georgia guy (talk) 19:00, 11 January 2020 (UTC)[reply]

Our B vitamins article says that as a class, "Each B vitamin is either a cofactor (generally a coenzyme) for key metabolic processes or is a precursor needed to make one." That article notes that there are substances formerly known as B4 and B8. DMacks (talk) 19:08, 11 January 2020 (UTC)[reply]

Thank you, but also vitamin C and vitamin K are cofactors for key metabolic processes. I really don't understand the citation from the article. 93.126.116.89 (talk) 04:51, 12 January 2020 (UTC)[reply]

January 12

Other animals with Sexual Maturity after age 10.

What animal species other than humans reach Sexual Maturity on average after age 10. I'm particularly looking for Mammals.Naraht (talk) 13:19, 12 January 2020 (UTC)[reply]

Haven't found an answer yet, but you may be interested in Lifespan and sexual maturity depends on your brain more than your body which says: "New Vanderbilt research finds how long humans and other warm-blooded animals live--and when they reach sexual maturity-- may have more to do with their brain than their body. More specifically, it is not animals with larger bodies or slower metabolic rates that live longer; it is animals with more neurons in the cerebral cortex, whatever the size of the body". So we're looking for an animal with more brain cells than us. Alansplodge (talk) 18:58, 12 January 2020 (UTC)[reply]

Elephants, probably all 3 extant species see Asian_elephant#Reproduction, African forest elephant#Reproduction, and African bush elephant#Reproduction. Bowhead_whale#Reproduction. Maybe Blue whale#Reproduction and birth. Nil Einne (talk) 19:16, 12 January 2020 (UTC)[reply]

Baboons can take 8 years; that's pretty high. Temerarius (talk) 23:43, 12 January 2020 (UTC)[reply]

Cloning Elon Musk

Could Elon Musk be cloned to help solve more complex problems in the future? 113.23.4.235 (talk) 14:29, 12 January 2020 (UTC)[reply]

They cloned a sheep so they can clone Musk, I suppose, but why? Did Elon Musk help solve problems of any complexity in the past? 2003:F5:6F05:EC00:D8E2:2B19:6E6D:B96 (talk) 15:37, 12 January 2020 (UTC) Marco Pagliero Berlin[reply]

There's no assurance that cloning someone will produce the same person again. Consider the Canseco twin brothers, Jose and Ozzie. Jose had an impact on baseball, while Ozzie did not. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:10, 12 January 2020 (UTC)[reply]

Elon Musk, just in case you we're wondering. Our human cloning article says that cloning is illegal in most civilised countries, but China seems to have fewer scruples; see Zhong Zhong and Hua Hua who are cloned monkeys. Alansplodge (talk) 19:03, 12 January 2020 (UTC)[reply]

I will assume good faith in the questioner, but I will also point out that there have been other (to put it politely) banana-balls crazy questions about the public figure in question from unregistered users recently. Temerarius (talk) 23:57, 12 January 2020 (UTC)[reply]

Hey, banana balls are tasty! (Hmm, should banana ball be turned blue?) Anyway, cloning humans is likely feasible in the medium-term future, though I will note the Ref Desk is not for predictions. Human clones already exist and have existed for as long as humans have. We call them identical twins. The act of human cloning would simply entail producing an identical twin intentionally, and probably from a person's existing somatic cells, as opposed to "natural" clones, which result when a human zygote spontaneously splits and develops into two fetuses. Cloning of human organs (as opposed to complete humans) is seeing a lot of serious research, as this would allow an organ "self-transplant", which would solve the problems of organ rejection and limited supply of transplant organs. --47.146.63.87 (talk) 05:22, 13 January 2020 (UTC)[reply]

Even when it is possible to clone somebody precisely, with no genetic problems introduced, there's still the issue of reproducing the exact environment that produced the original. There may be something equivalent to the butterfly effect, where a seemingly trivial event early in life sets the course for that person's entire life. NonmalignedNations (talk) 08:31, 13 January 2020 (UTC)[reply]

See Nature versus nurture and also The Boys from Brazil (novel). Even if the exact upbringing is applied, (impossible) it is not guaranteed that the same person would emerge. Thanks. Anton. — Preceding unsigned comment added by 81.131.40.58 (talk) 10:19, 13 January 2020 (UTC)[reply]

Methane

Is Methane gas and general gas as expelled in the act of flatus and defecation heavier or lighter than air? I need to change clothes daily in a public toilet and it often stinks to the point of having to hold my breath. Am I better off taking a breath when I change my shoes, or by standing on my toes? Google has not been of much help. Please assume good faith. Thanks. Anton. 81.131.40.58 (talk) 10:56, 13 January 2020 (UTC)[reply]

@@ Line 250: / Line 250: @@
 :Even when it is possible to clone somebody precisely, with no genetic problems introduced, there's still the issue of reproducing the exact environment that produced the original. There may be something equivalent to the [[butterfly effect]], where a seemingly trivial event early in life sets the course for that person's entire life. [[User:NonmalignedNations|NonmalignedNations]] ([[User talk:NonmalignedNations|talk]]) 08:31, 13 January 2020 (UTC)
 ::See [[Nature versus nurture]] and also [[The Boys from Brazil (novel)]].  Even if the exact upbringing is applied, (impossible) it is not guaranteed that the same person would emerge.  Thanks.  Anton.  <!-- Template:Unsigned IP --><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/81.131.40.58|81.131.40.58]] ([[User talk:81.131.40.58#top|talk]]) 10:19, 13 January 2020 (UTC)</small> <!--Autosigned by SineBot-->
+== Methane ==
+Is [[Methane gas]] and general gas as expelled in the act of [[flatus]] and [[defecation]] heavier or lighter than air?  I need to change clothes daily in a public toilet and it often stinks to the point of having to hold my breath.  Am I better off taking a breath when I change my shoes, or by standing on my toes?  Google has not been of much help.  Please assume good faith.  Thanks.  Anton.  [[Special:Contributions/81.131.40.58|81.131.40.58]] ([[User talk:81.131.40.58|talk]]) 10:56, 13 January 2020 (UTC)