Wikipedia:Reference desk/Science

Jump to navigation Jump to search

The Wikipedia Reference Desk covering the topic of science.

Welcome to the science reference desk.
Want a faster answer?

Main page: Help searching Wikipedia

How can I get my question answered?

  • Provide a short header that gives the general topic of the question.
  • Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
  • Post your question to only one desk.
  • Don't post personal contact information – it will be removed. All answers will be provided here.
  • Specific questions, that are likely to produce reliable sources, will tend to get clearer answers.
  • Note:
    • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
    • We don't answer requests for opinions, predictions or debate.
    • We don't do your homework for you, though we'll help you past the stuck point.
    • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.



How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

  • The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
 
Choose a topic:
 
See also:
Help desk
Village pump
Help manual


May 29[edit]

Looking for a source for Cotyledon tomentosa synonym[edit]

Hi, I am working on expanding Cotyledon tomentosa, and I am having trouble finding a source for an obscure taxonomic synonym. The SANBI website [1] lists that Cotyledon ladismithensis Boom may be a synonym for C. tomentosa subsp. tomentosa, but I haven't been able to track down this particular taxonomy, especially since the same name was used by Poelln. and is now a synonym for C. tomentosa subsp. ladismithensis. Here, Boom refers to Boudewijn Karel Boom, so I looked through the worldcat list of publications and narrowed my search to two works,

  • An article: Boom, B. K. Notes on nomenclature for succulent plants. (In Dutch.) Succulenta 11:141-145. Nov. 1959.
  • A book: Notities over succulenten [2]

The first article I was able to find in an archive here: [3] and even though I cannot read Dutch, this article does not mention C. tomentosa at all. So I'm assuming that the original SANBI Red List listing is referring to the book, but I have not been able to find this book anywhere online. In addition, I haven't been able to find any secondary sources listing C. ladismithensis Boom as a synonym for C. tomentosa. Any assistance in finding either the book or a secondary source listing Boom as a synonym would be greatly appreciated! Sn1per (talk) 05:23, 29 May 2020 (UTC)

Another possible book: [4] mentions "The fourth and last part [of the books Flora Der Cultuurgewassen Van Nederland] will deal with the assortment of succulent plants grown in special collections" but I can't find any evidence of this part actually existing. Sn1per (talk) 05:40, 29 May 2020 (UTC)
I have found the original source! So the worldcat entry for the book gave the crucial insight that the book is actually "Articles reprinted from Succulenta, 1957-1958." And since I found the Succulenta archive, I searched the 1957 and 1958 archives and found the article. Indeed, it is "Codyledon ladysmitiensis Poellnitz" by B. K. Boom, in Succulenta 1958, issue 2, and the description of the article is much closer to subsp. cotyledon than subsp. ladysmithiensis. Cheers, Sn1per (talk) 15:15, 29 May 2020 (UTC)

May 30[edit]

What if Rocket launch speed is very slow and constant?[edit]

Not a serious question: disruptive user copying questions from other sites.
The following discussion has been closed. Please do not modify it.


If I walk slow , I reach destination at slow. Rocket launch speed is very slow and constant.

Will it reach the destination without obstacles? Will Escape velocity disturbs the rocket? Ram nareshji (talk) 02:30, 30 May 2020 (UTC)

How "slow" a rocket are you thinking of? ←Baseball Bugs What's up, Doc? carrots→ 02:36, 30 May 2020 (UTC)
Escape velocity decreases as you climb away from the planet. If you are able to maintain a constant speed upward then eventually you will reach a height where you are moving faster than the escape velocity for that height, which means you can leave the planet and go anywhwere. The reason nobody does this with real rockets is that it would require huge amounts of fuel. As you are climbing slowly, you are having to burn extra fuel to lift the extra fuel, and more fuel to lift that extra fuel, and so on. --76.71.5.208 (talk) 03:41, 30 May 2020 (UTC)
Unless you have the right fuel - Grand Fenwick wine seems to do the trick... WegianWarrior (talk) 08:38, 30 May 2020 (UTC)
You could very slowly ascend to some great height in the atmosphere, and then somehow accelerate up to orbital speed (most of the energy needed is in gaining tangential speed, not height). This is horribly inefficient if done with rocket fuel. Basically as a thought experiment, if you were to hover in mid air then all the fuel you use would contribute nothing towards getting you into orbit, and that's the extreme example of a slow ascent. Greglocock (talk) 20:38, 30 May 2020 (UTC)

Which first scientist declared space has Weightlessness?[edit]

Not a serious question: disruptive user copying questions from other sites.
The following discussion has been closed. Please do not modify it.

Which first scientist declared space has no gravity? Ram nareshji (talk) 17:18, 30 May 2020 (UTC)

What does that even mean? ←Baseball Bugs What's up, Doc? carrots→ 17:25, 30 May 2020 (UTC)

Is it Isaac Newton told that space there is no gravity? Ram nareshji (talk) 17:40, 30 May 2020 (UTC)

I don't believe that anybody ever said that in space there is no gravity. Can you please show a reference where we can read this? If not I don't think we should try to answer such a question. In space there is gravity, as e.g. Pluto's orbit demonstrates. 2003:F5:6F08:8200:6C05:21DC:9237:7EDF (talk) 17:52, 30 May 2020 (UTC) Marco PB

I changed question now, who first told Weightlessness can observed in space ?Ram nareshji (talk) 18:00, 30 May 2020 (UTC)

You're not weightless in space. If you're in orbit, you're in a state of continuous free-fall. ←Baseball Bugs What's up, Doc? carrots→ 18:55, 30 May 2020 (UTC)
You are right of course, but in every day language we call weightlessness "the complete or near-complete absence of the sensation of weight" as one can experience in a free fall situation, like e. g. on the rollercoaster, on the Vomit Comet, in any stable orbit and exactly where the gravitational attraction between the Earth and the Moon balance each other (and ignoring the one from the Sun, Mars, Alpha centauri, Sagittarius A ...)
And yes, Isaac Newton is said [[5]] to have written somewhere that objects are in free fall when they are acted upon only by gravity, so he can well have been the first physicist to mention this effect in relation to gravity, but for example some fifty years before Newton also G. Galilei was interested in free fall and could have had some idea of weightlessness. 2003:F5:6F08:8200:6C05:21DC:9237:7EDF (talk) 20:32, 30 May 2020 (UTC) Marco PB

May 31[edit]

Question about coordination compounds[edit]

How can I know how many ligands coordinated with a metal? For example, a d-metal cation from a salt dissolved in water: how is possibile to estimate how many water molecules coordinate with metal?--87.9.210.194 (talk) 08:12, 31 May 2020 (UTC)

See Metal ions in aqueous solution. And there is a relatively recent review from Ingmar Persson on this. However you must also bear in mind that most of the 4d and 5d metals have water easily displaced from the coordination sphere by other ligands and therefore it is difficult to find their cations (try perchloric acid media to avoid this problem, IIRC). Double sharp (talk) 10:03, 31 May 2020 (UTC)

Perpetuum Mobile[edit]

I found one! No of course I didn't. :) But I don't see why it wouldn't work.
Take a (high) column with a heavy gas in it and at the bottom some water with electrodes in it. Hydrogen and oxygen will rise to the top. There, a fuel cell combines the two, producing water. This water now has an increased potential energy because of the height, with which energy might be produced. The electricity from the fuel cell is used for the electrolysis at the bottom.
Of course the fuel cell and the electrolysis wiil not be 100% efficient, but that is independent of the height, so that can't explain it. The length of the electrical wire between the two is dependent on the height, but I doubt that that would explain it.
I chose a heavy gas because else the oxygen might not rise enough. In Earth's atmospere one could use the oxygen at the top, but that might then provide an explanation. I doubt it, but this way I avoided that issue.
So where is the error in my reasoning? DirkvdM (talk) 12:13, 31 May 2020 (UTC)

  • You already said it: "Not 100% efficient." ←Baseball Bugs What's up, Doc? carrots→ 12:31, 31 May 2020 (UTC)
    • That doesn’t really address what the OP wrote. Brianjd (talk) 12:41, 31 May 2020 (UTC)
  • I’m not sure what effect the height would have exactly, but I know this:
    • The potential energy won’t be recovered by the fuel cell. It will remain with the water (to put it in simple terms) and will be lost when the water falls back to the bottom, where it can undergo electrolysis again.
    Therefore, any loss (even if independent of the height) means that the fuel cell won’t produce enough energy to electrolyse the same amount of water. With less water electrolysed, there will be less hydrogen and oxygen to run the fuel cell at the top, meaning it will produce even less energy, and so on.
Brianjd (talk) 12:41, 31 May 2020 (UTC)
  • Perhaps I should have said “power” instead of “energy”. Brianjd (talk) 12:43, 31 May 2020 (UTC)
Why it does not work even in theory is that it takes more energy to convert water to hydrogen and oxygen at a higher pressure than at a lower pressure. A simpler version of this involves water vapour in the earth's atmosphere, which goes up and then condenses to liquid or solid water and then falls as rain or snow. Heat is exchanged in this process. Graeme Bartlett (talk) 12:54, 31 May 2020 (UTC)
Ah, that could indeed explain it. The gained potential energy depends on how high the hydrogen and (especially) oxygen would rise, which depends on the amount and specific mass of the other gas, which both would influence the pressure on the water. If the efficiency of the electrolysis decreases at the same rate the pressure rises then it would indeed not work.
The article on Electrolysis mentions that the efficiency depends on pressure, but I don't see a further explanation. (Maybe an idea to add that?) So I don't understand why this is the case, but in the real world there is oxygen in the atmosphere. The hydrogen rises higher, so the water could be produced at a higher altitude. Might this be a way to extract energy from the distribution of gases in the atmosphere? DirkvdM (talk) 14:17, 31 May 2020 (UTC)
  • @DirkvdM: Regarding your first paragraph, it doesn’t matter, because you don’t get to turn that potential energy into electricity. Please see my comment above. I’ll leave the second paragraph for someone else to respond to. Brianjd (talk) 14:24, 31 May 2020 (UTC)
Of course the potential energy of the water can be harvested somehow, eg with a turbine. For a perpetuum mobile persé that is not necesary, but utilising excess energy could save the world and make me the new Shell. :) DirkvdM (talk) 15:32, 31 May 2020 (UTC)
  • Everyone else is making good comments, but I can’t get over this potential energy thing. How are you going to prevent the gases from resisting the turbine on the way up?
I’m still confused about that second paragraph in your previous comment. Brianjd (talk) 02:14, 1 June 2020 (UTC)

It turn out that even if you assume zero friction, zero electrical resistance, etc. the best you can do is something that comes so close to moving perpetually that you can't measure the energy loss. Two solid objects orbiting each other alone in deep space would be an example of this. But you can never get a surplus of energy that you can harvest forever. If your calculations say that you can, you missed something. For a great example of something that seems like it might work, see Maxwell's Demon. --Guy Macon (talk) 16:35, 31 May 2020 (UTC)

Yes, I know a perpetuum mobile can't work out of principle. That was indeed my point. See the first line of my question. DirkvdM (talk) 07:42, 1 June 2020 (UTC)


There appears to be some confusion about my idea.

  • First, there is the closed energy system with the electrolysis which produces the hydrogen for the fuel cell, which produces the electricity for the electrolysis, etc, etc. This is the perpetuum mobile, which of course wouldn't work because of friction and efficiency never being 100%.
  • But then, there is the water that is produced at the top. This increases the potential energy of the water (which might be harvested in some way, eg with a turbine in a tube through whicht the water falls). This was what confused me, but Graeme Bartlett explained that (if I understood it correctly) even under ideal circumstances the gas pressure needed to make the hydrogen rise makes the electrolysis less efficient, giving the energy loss that compensates for the energy gain.
  • However, then I thought about using the oxygen in the atmosphere instead of the oxygen produced by the electrolysis. With only the lighter hydrogen rising, less gas pressure is needed, making the electrolysis more efficient, circumventing the issue. Of course, this is not a perpetuum mobile, because there apparently is an energy potential in the composition of the atmosphere, which is harvested by this system. Oxygen is produced at the bottom and bonded at the top.

On a side note, the oxygen at the bottom might be used in a green house. Eg for food production. Or just to take CO2 out of the air, helping to solve climate change. DirkvdM (talk) 07:42, 1 June 2020 (UTC)

Even if the efficiencies of electrolysis and fuel cell are 100%, it won't work. The redox potential of a half-cell depends on the concentrations of the chemicals involved. As the pressure drops, so does the concentration, so that the fuel cell at the top will provide a lower voltage than the electrolysis cell uses. Using atmospheric oxygen won't help, as the concentration of the oxygen at your fuel cell will still be lower than at your electrolysis cell (and even lower than if you had used the pure oxygen from the electrolysis cell, so it will, in fact, be worse). PiusImpavidus (talk) 08:05, 1 June 2020 (UTC)
Ah, I was already wondering what any effects of the lower air pressure might be. But is this a fundamental problem? Electricity is not a strong point of mine. Could it be solved by just using more fuel cells? Note, though, that this is an open system. If it works at all, then it should keep on working because any used oxygen (or hydrogen) will be replenished (assuming air currents), so the pressure remains constant and nothing fundamentally changes.
Or, from a different angle, can't one simply use a voltage converter? Of course that would introduce more inefficiency.
On a practical note however, with a production of 1 l of water per second at an altitude of 1 km, the produced power would be 1 kg/s * 1000 m * 10 m/s² = 10 kW. Taking inefficiencies into account, that would probably be about 1 kW (or less). So to have the same power production as a medium sized wind turbine (1 MW), 1 m³ of water should be produced per second. That's a lot. The wind turbine might be a more practical thing to build. Ah well, another 'brilliant' idea down the drain. :) DirkvdM (talk) 08:40, 1 June 2020 (UTC)

Outsourcing of engineering systems integration.[edit]

Is the outsourcing of systems integration now common to all engineering industries as it is becoming in civil engineering? As in the top level client just specifies and oversees what they want whilst the integration is outsourced to a tier 1 integration supplier Clover345 (talk) 17:14, 31 May 2020 (UTC)

All engineering industries? I do a lot of engineering involving putting five cent microelectronics into toys, and the only systems integration we do is when the IT department rolls out an upgrade. Also, we don't have any "top level client" who generates specifications. We have a bunch of children who bug their parents for the latest toy. I have also worked for companies that make hydraulic/pneumatic components. Engineering at those companies is pretty much all systems integration, but is never outsourced because nobody else knows how to, say, put together a pneumatic system that puts out 20 burritos a second. It is important to realize that there are a wide variety of engineering jobs out there. It is always amusing watching someone assume that every computer has megabytes of RAM when I work with systems that have 64 nybbles (not bytes) of RAM. --Guy Macon (talk) 19:02, 31 May 2020 (UTC)
@Guy Macon: I think it's more common for an 'ordinary user' to expect tens of gigabytes of RAM in a todays computer rather that a few megabytes. :) --CiaPan (talk) 19:21, 31 May 2020 (UTC)
Well yes, “all” is a broad generalisation but was just wondering if it happens a lot in other industries. Clover345 (talk) 19:45, 31 May 2020 (UTC)
What's ironic is that that "ordinary user who expects tens of gigabytes of RAM" mentioned above is probaly typing on a keyboard that contains a computer with 4K of RAM, using a mouse that contains 2K of RAM, looking at a monitor that might have 512K of RAM -- but maybe a lot more -- eating toast made with a toaster that has 512 bytes of RAM, drives a car that has several megabytes of RAM, etc. etc. Nowadays even light bulbs have computers inside them. Tiny computer are all around you but (if I do my job correctly) you don't recognize, say, your thermostat or digital watch as being a computer. --Guy Macon (talk) 00:44, 1 June 2020 (UTC)
Not in automotive. The OEM is the system integrator. In fact GM have or had a formal prototype phase called Integration Prototype, not a bad idea, at least you know what it is for. However sometimes OEMs outsource the complete design and development of models to third parties, in which case I suppose they are the system integrator. For various reasons it's not a great idea unless they are also going to manufacture it. say Magna, Stey_Puch among others do that sort of thing. Greglocock (talk) 23:31, 31 May 2020 (UTC)

Polyunsaturated fat degradation speed[edit]

What's the most unsaturated 22-carbon cis-fatty acid on Template:Fatty acids who's triglycerides take at least 3 seconds to degrade to the naked senses when first touching air? So you have an essentially inert bottle, airtight, fill it with pure triglyceride (without free fatty acid, foreign fatty acid, preservative or any other impurity) that has never touched gas besides neon and its own vapor and break the seal (in the dark if need be) well before a human could tell it's degrading (use a Star Trek transporter if you have to) and (after the surface is touching mostly air instead of neon) taste the surface or sniff it or whichever sense is best, I'm guessing you could tell by flavor before stickiness, sight, stirring resistance, viscosity eyeballing etc. but who knows. How soon can you detect the degradation without instruments if you know what to check? Even a lower bound for double bond count would be nice.

2. Same thing but 20 carbons, 18, 16, 24 and any other biologically important numbers.

3. Why does butter degrade so fast on the kitchen table in both appearance and flavor compared to extra virgin olive oil without the cap when butter has almost no double bonds at all? Sagittarian Milky Way (talk) 20:27, 31 May 2020 (UTC)

Regarding 3, I believe the reason is olive oil contains high levels of polyphenol antioxidants that, well, inhibit oxidation. They're also what's responsible for much of olive oil's characteristic taste and mouthfeel. Butter is refined and mostly fat. The oil still does degrade over time when exposed to air. --47.146.63.87 (talk) 22:34, 31 May 2020 (UTC)
It also depends on what we mean by "degradation." Butter, for example, is a mixture of milk fat that is almost entirely saturated, but that's only about 80% of the content. The rest is milk solids, which aren't fat, and water. Water isn't generally something that mixes well with fats, and worse with saturated fats. In butter, it exists as an emulsion, but as you leave it out at room temperature, that emulsion will break overtime and you will be left components that don't want to mix. Get some ghee, which is much more pure milk fat, and you won't see this happen nearly as much. So, is the degradation that we see from the fats degrading, or from other non-fat components degrading or separating from the fats? --OuroborosCobra (talk) 23:12, 31 May 2020 (UTC)
So olive oil is slower than its double bond amounts imply (which explains why linseed oil is so much faster with not that much more bonds) and butter is not even a real fat but like a fat-water frappé. Sagittarian Milky Way (talk) 20:29, 1 June 2020 (UTC)
Butter is mostly fat, and the part that is fat, is really fat. There are techniques that process butter to remove most of the water and milk-solid content, such as Ghee and clarified butter. But it is incorrect to say "not even fat". It would be better to say "not only fat". Still mostly fat. --Jayron32 18:16, 2 June 2020 (UTC)
I knew about ghee/clarified butter and assumed the unclarified kind wasn't udderly, udderly free of water and milk solids but would've guessed a few percent hydrophilic stuff tops, at least in the modern machine-made stuff. 20 percent surprised me. So I guess if you see water on old butter it isn't all condensation or oxidation products. Sagittarian Milky Way (talk) 00:10, 3 June 2020 (UTC)

June 1[edit]

Is there a legal/fiscal/cultural reason why fields in Estonia might generally have a grove or orchard in them[edit]

(as per [in Estonia#Orchards]) I was wondering why there was a preponderance of trees within (as opposed to on the periphery of) fields in Estonia. I noticed this as I was flying into Talinn. Is this the result of legislation, or culture. Or have I imagined it? Bogger (talk) 17:29, 1 June 2020 (UTC)

I think you are referring to wooded meadows. Our article is a bit thin, though if you google "wooded meadows Estonia", results such as this and this crop up, which give quite a bit of background general info. PaleCloudedWhite (talk) 06:33, 2 June 2020 (UTC)

Benevolent virus mutation[edit]

I've heard that as epidemics spread viruses often mutate to a less deadly form. I've heard this as an explanation why the death rate in Bergamo was so high (0.57% of everyone) but farther from Italy death rates were lower even when selecting for people with antibodies (0.37% in Heinsberg).

I can understand how this works for highly deadly viruses like ebola, but is this effect really at play for such low mortality viruses as corona? 95.168.122.249 (talk) 17:38, 1 June 2020 (UTC)

I am pretty sure it applies to all infectious disease, but I am having a hard time believing that we can see the effect over such a short time span. --Guy Macon (talk) 18:19, 1 June 2020 (UTC)
0.3% of New York City died according to excess death and not everyone caught it while Italy is one of the oldest countries on Earth. The normal amount of death in NYC is surprisingly low actually, only about 158 a day which implies an average death age of 150 years. That's ridiculous so obviously a lot of people just leave before they get very old. Often to Florida. There's probably even a positive balance of trade of people that come to New York City for medical treatment or are sent there from suburban or rural hospitals and die (almost 2/3rds of the metro area lives outside city limits). Considering that New Yorkers die half as much as other first worlders due mostly to low chance of death by old age at the residents' age Bergamo doesn't seem like a freak outlier after all. Sagittarian Milky Way (talk) 20:14, 1 June 2020 (UTC)
Well, even if a disease doesn't kill you, if it makes you so sick that you avoid others (and they avoid you) it may not have much chance to infect others before your immune system overcomes it. --Khajidha (talk) 14:20, 2 June 2020 (UTC)

June 2[edit]

Partners[edit]

Moved to: WP:RDH #Partners
The following discussion has been closed. Please do not modify it.

Which articles deal with how humans select romantic partners? Benjamin (talk) 01:12, 2 June 2020 (UTC)

If you google "wikipedia mate selection", several articles come up, and you could review them. ←Baseball Bugs What's up, Doc? carrots→ 01:22, 2 June 2020 (UTC)
Which one in particular? To be clear, I'm asking romantic partners, not sexual reproduction or evolution. Benjamin (talk) 02:46, 2 June 2020 (UTC)
Wikipedia:Reference desk/Humanities might be better equipped to answer. --OuroborosCobra (talk) 02:55, 2 June 2020 (UTC)
(Closed & moved to prevent duplicate discussions) 107.15.157.44 (talk) 05:13, 2 June 2020 (UTC)

List of all 21 Indian cities to run out of groundwater[edit]

There are many reports that 21 Indian cities will run out of groundwater in future. But everywhere I could read only Delhi, Mumbai, Chennai, Bengaluru, Hyderabad. I couldn't find the full list of 21 cities. http://www.aljazeera.com/news/2019/06/india-running-water-fast-190620085139572.html — Preceding unsigned comment added by സൂര്യചന്ദ്രൻ ഗ്രഹം (talkcontribs) 04:19, 2 June 2020 (UTC)

That article and the NDTV one it cites are dated 20 June 2019, and both cite a report by NITI Aayog. I cannot find a reoport on their website on this topic from that approximate time, and the two "Composite Water Management Index" reports I found from any timeframe do not appear to list 21 cities. DMacks (talk) 04:36, 2 June 2020 (UTC)
Here is the report: [6] (I haven't read it) -- As cited here: Bhasker Tripathi (25 June 2018). "Bengaluru, Delhi, Chennai among 21 cities to run out of groundwater by 2020". Tech2. Technology News, Firstpost.107.15.157.44 (talk) 09:56, 2 June 2020 (UTC)
Question: are there any places anywhere in the world that actually have run out of groundwater as opposed to predictions that they are going to run out of groundwater? I don't mean "the old well ran dry but a new, deeper well is supplying groundwater", nor do I mean places that never had any groundwater. I searched and found plenty of places that are depleting their groundwater supplies faster than nature is replenishing them, but I could not find any examples of places that actually ran out of groundwater. I am sure that such places exist. --Guy Macon (talk) 15:25, 2 June 2020 (UTC)
It may depend on your definition of "run out", but the Australian town of Stanthorpe, Queensland is now fully dependent on water being carted in from outside because it has "run out" of its own. -- Jack of Oz [pleasantries] 23:25, 2 June 2020 (UTC)
I searched for reliable sources (as soon as I saw that Daily Mail Link I refused to look at it -- to high a chance that they got most of the story right but added a few lies to make it better clickbait.)
From what I can gather from the other side of the globe,[7] Stanthorpe ran out of water but not groundwater. They were getting water from Storm King Dam, and now they are having to cart water in trucks from Connolly Dam and dump it in Storm King Dam just to keep enough in the bottom so they send it to the town using existing pipes. And they are a couple of years away from emptying Connolly Dam.
The same source says "When the above-ground dams run out of water, the council will have to switch to using bores, which are already under pressure from agricultural and commercial use" (I am assuming the a Bore is what we in California call a well).
Another Australian source[8] says that "Currently the shire is in discussions with the Queensland Government about getting access to the Dalrymple and Cunningham alluvium, underground water sources near Allora north of Stanthorpe." I couldn't find any sources that discuss how much groundwater is in those groundwater sources.
The Guardian has a related story[9] which sort of implies not much water available underground, but they didn't give any actual numbers.
I just hope that I won't do a search a few years from now and see a bunch of "we told you we were going to run out of groundwater and now we have!" stories from around the globe.
Question: when [10] talks about "standpipes" and " Avdata key holders" what are they talking about? Is that a Standpipe (street)? --Guy Macon (talk) 01:29, 3 June 2020 (UTC)
Probably holders of one of these [11], maybe one specific for the area, not sure [12]. Nil Einne (talk) 09:14, 3 June 2020 (UTC)

E = hf[edit]

Does apply to all waves, including longitudinal waves like sound, or is it just used to describe electromagnetic waves? --PuzzledvegetableIs it teatime already? 20:17, 2 June 2020 (UTC) + edit--PuzzledvegetableIs it teatime already? 22:58, 2 June 2020 (UTC)

You probably meant electromagnetic waves. Ruslik_Zero 20:26, 2 June 2020 (UTC)
Yes, yes I did. Thank you. --PuzzledvegetableIs it teatime already? 22:58, 2 June 2020 (UTC)
From Photon energy: Photon energy is the energy carried by a single photon... the photon energy equation can be simplified to . Sound waves are not made out of photons. --Guy Macon (talk) 21:18, 2 June 2020 (UTC)
No, but in some sense they are "made out of" phonons, and from that article it appears to me that the energy associated with a phonon is indeed hf. --Trovatore (talk) 23:09, 2 June 2020 (UTC)
Not really. Only in solids and a few oddball liquids do phonons even make sense; the phenomenon is nonseniscal in gaseous phases with free movement of particles, such that the movement of a mechanical vibration can be modeled perfectly in a non-quantum way. Phonons really only make sense when there are highly-constrained single-frequency vibrations happening accross chemical bonds, which being composed of electrons, require some quantum explanation. For sound waves moving through air, there's no quantumness to be had. It's entirely a classical phenomenon. --Jayron32 05:35, 3 June 2020 (UTC)
  • No, it really only applies to quantum phenomenon. E=hf applies to electromagnetic waves because there is no medium in any real sense, what is vibrating is simply the electromagnetic field, which is just a series of numbers (well, messy numbers, specifically a 4x4 matrix known as the Electromagnetic tensor, but it's still just a complicated number) assigned to points in space, and not a material in any meaningful sense. The energy carried by that vibration in the field is just a function of the frequency of that vibration. It's a simple calculation because it is functionally just a single kind of energy, kinetic energy of the field itself. The energy carried by a sound wave is a fantastically more complicated matter, as it involves the actual motion of actual matter, and matter is WAY messier than a field. Consider that the specific matter itself matters, including which atoms there are, and how they are organized and how they interact with each other and since we now have actual interactions between pieces of matter, now we have to introduce a new term, potential energy and wow does it become a mess. Sound energy has an equation for you to use, but you have a LOT more variables to plug in, because matter is so much more complex than a field. EM fields, by comparison, even with their messy tensor mathematics, are conceptually much easier to reduce to a simple equation, E=hf. The phonon thing described above is a real phenomenon, but it really only manifests itself in some very specific situations; it's an important tool in all sorts of first-principles modeling of important phenomena, but basic sound like "I yell and you hear me" isn't one of them. --Jayron32 05:51, 3 June 2020 (UTC)
The equation E = h f applies to all phenomena that exhibit oscillations at a fixed frequency. It is more precisely written as E = (n+1/2) h f, n is the number of quanta, or it refers to the nth excited state of the system and the 1/2 h f for n = 0 is the ground state energy, also called the vacuum energy. The energy contained in a single mode of sound waves, electric circuits like LC circuits are all given by this equation. For example in any electric circuit at room temperature is subject to Johnson–Nyquist noise which is due to the thermal motion of electrons in the circuit. Suppose that you cool the electric circuit to low temperatures to eliminate the noise. The E = n h f law will then become visible in the form of the Planck distribution of the frequency components of the noise. High frequency components of the noise are then cut off. You can then ask of the noise will become zero at absolute zero. The answer is no, because the formula is not actually E = n h f, but E = (n + 1/2) h f and at temperatures so low that the electronic degrees of freedom are all in the ground state, you still have noise due to quantum fluctuations that are present in the ground state. Count Iblis (talk) 13:34, 4 June 2020 (UTC)
That is true, but it is only strictly true for a portion of the energy of the wave. The problem with mechanical waves, like sound, is that the energy of those waves is dependent on all sorts of messy interactions throughout the medium the wave is traveling in. The reason why we most associate that equation with things like photons is that light has no medium, so its energy is completely described by that equation. A "phonon" in this context, as described above, is basically a way to conceive of the E = hf portion of a mechanical wave energy in crystalline media. It isn't very useful when trying to calculate the total energy of sound, however. --Jayron32 15:34, 4 June 2020 (UTC)

June 3[edit]

MED: List of diagnoses added to the ICD-11[edit]

This may be a big ask, but there must be a list somewhere of new diagnoses for the ICD-11? WHO have finalised the list, but which are new? Amousey (talk) 12:04, 3 June 2020 (UTC)

You can start with the WHO's Transition Guide, a short book available at zero-cost, that helps organizations transition from older systems to the new ICD-11 system. It contains a few short chapters on what is new and why they justify the changes; and they reference lots of additional process documents to help you navigate the specifics.
I do not think you will find a more compact form that lists what has been added and removed.
I am a computer programmer who is, more recently, a very regular reader of legal and other non-technical documents (not to mention, of course, technical-documents other-than-software-source-code); and my colleagues and I often joke about how wonderful it would be if we could convince other intellectual-communities to adopt something akin to unidiff - but frankly, this kind of compact form just doesn't exist in widespread use outside of the domain of computer-software.
With a little bit of tempered reflection, let me just summarize my remarks by stating for the record: the reason why we won't find a compact listing of additions- and subtractions- is because in these domains, such a format would be a misrepresentation. That is why the users of such systems, like ICD-11, publish long-form books and guides, and do not publish "code patches."
At the same time - nothing, other than intellectual integrity, actually precludes an enthusiastic researcher from dumping the entire ICD-10 and ICD-11 content to text, and running "diff"...
Nimur (talk) 17:17, 3 June 2020 (UTC)

June 4[edit]

Space X spacesuits[edit]

Why do the Space X dragon crew need a spacesuit during launch and docking but not for the phase in between? I assume it’s to do with cabin pressurisation. Clover345 (talk) 16:53, 4 June 2020 (UTC)

It isn't the same spacesuit they would wear during extravehicular activity; it's a special suit designed only for launch and re-entry portions of the flight. I can't find a Wikipedia article on the current suits, but the previous suits, known as "pumpkin suits" for their orange color, were known as the Advanced Crew Escape Suit (1990s and 2000s) and the Launch Entry Suit (1980s-1990s). The Russian version is known as the Sokol space suit. These are designed to protect the crew in case of accidental de-pressurization during launch and re-entry. The reason for their use isn't because there's anything wrong with the air in the cabin during those times, normally. Hypothetically, they could breath in the cabin normally during those times. They are designed as emergency suits in case cabin pressure is lost during the extremely violent launch and re-entry phases of the mission. If cabin pressure were suddenly lost, and they didn't have the suits on, they would asphyxiate; under the high-g-force periods of launch and re-entry, they are strapped in to their chairs anyways, so they couldn't get out and put one on. During normal orbital flight, 1) there is basically no real stresses on the vehicle to speak of, so there's much less chance of something going wrong and 2) even if it did, the astronauts aren't strapped in to chairs and could get into their emergency suits as needed. During launch and re-entry, you wear your emergency suit because you can't get to it if you needed it. --Jayron32 17:33, 4 June 2020 (UTC)
You need to wear safety gear when something exciting might happen. During take off you should wear a helmet. When you might bump into a space station you should gear up. Between those two, when you are just coasting, it is more comfortable to wear a T-shirt and have a nap. 85.76.104.122 (talk) 17:39, 4 June 2020 (UTC)
This is not specific to Dragon. It's the same in Soyuz and previously Shuttle and I think Apollo and some of the Gemini flights. The reason is that not much is expected to go wrong when just coasting and as spacesuits are not very comfortable, the astronauts take them off. During launch, docking, undocking and landing, more can go wrong. A leak may appear during ascent (Challenger, although that wasn't survivable anyway), the ship can collide with the space station (Progress M-34), a valve may open prematurely (Soyuz 11), all of which may lead to depressurisation of the spacecraft. So they wear spacesuits just in case during those manoeuvres. If nothing goes wrong, the spacecraft remains pressurised, for modern spacecraft at normal atmospheric pressure. PiusImpavidus (talk) 17:49, 4 June 2020 (UTC)

Wooden vs. rubber bullets[edit]

I wonder what the material difference is? I first heard about the existence of wooden bullets a week ago in conjunction with the current disturbances. Before it had always been - rubber bullets. Are they more effective? Thanks, - AboutFace 22 (talk) 18:49, 4 June 2020 (UTC)

Effective at what? Putting eyes out?[13]Baseball Bugs What's up, Doc? carrots→ 18:57, 4 June 2020 (UTC)
@AboutFace 22: there are articles on these: Rubber bullet and Wooden bullet. The latter is short but it does mention it is intended to inflict Pain_compliance. RudolfRed (talk) 21:02, 4 June 2020 (UTC)
Note that although the media often talk about rubber bullets, as I understand it in reality nowadays plastic bullets are very common, potentially more common at least in a number of countries. See the above linked articles and also plastic bullet along with [14] [15] [16] [17] [18]. Find good stats on this seems to be difficult since it isn't always clear when someone calls something a "rubber bullet" whether these are really rubber bullets (i.e. partly or completely made of something which can reasonably be called rubber natural or synthetic) or instead something which can reasonably be called "plastic" but not rubber. Nil Einne (talk) 22:16, 4 June 2020 (UTC)

Human livers now synthesized in rats.[edit]

Greetings!

I've been sporadically following the advancing of tissue engineering, and for the longest time, it seemed that only simple tissues such as skin, bone, and cartilage had been successfully synthesized. The other day, however, the online magazine Popular Mechanics [19] reported that a research team has successfully implanted complete (albeit miniature) human livers, synthesized from the genes of donated human skin cells, inside of laboratory rats.

As I apprehend it, the liver is by far the most complicated and sophisticated organ in the human body, owing to its myriad physiological functions and unique regeneration ability. My question thus is as follows:

Will it now become easier for tissue engineers to replicate simpler human organs such as the kidney, heart, stomach, lung, and pancreas?

--Thank You!

Pine (talk) 19:10, 4 June 2020 (UTC)


June 5[edit]

Oxygen in photosynthesis[edit]

In the 3rd sentence of the photosynthesis article, it states that: "In most cases, oxygen is also released as a waste product." I was wondering, in a broad sense, what that means. In which cases does this not occur? My 9th grade daughter learning bio asked me this question and I didn't know what it could be. Thanks! DRosenbach (Talk | Contribs) 00:09, 5 June 2020 (UTC)

Possibly referring to plants that use close their stomata in daytime and use CAM photosynthesis. Conditions might allow them to use all self-produced oxygen in respiration while releasing little. Rmhermen (talk) 01:02, 5 June 2020 (UTC)
High school bio teacher chiming in. Even with CAM, oxygen is still produced as a waste product, because the light reaction is where oxygen is produced as the product due to photolysis, while CAM only changes the particulars of the carbon fixation pathway. Rather, this statement is a reference to anoxygenic photosynthesis (photosynthesis that does not produce oxygen), which some bacteria are able to perform. The vast majority of organisms today, however, produce oxygen during photosynthesis. bibliomaniac15 01:16, 5 June 2020 (UTC)