[[Special:Contributions/37.53.235.112|37.53.235.112]] ([[User talk:37.53.235.112|talk]]) 05:33, 22 April 2016 (UTC)
[[Special:Contributions/37.53.235.112|37.53.235.112]] ([[User talk:37.53.235.112|talk]]) 05:33, 22 April 2016 (UTC)
== Flu shot... ==
I am having a hard time finding a reliable source for this one.. "How many people die from the flu shot every year?" Such a simple inquiry... unfortunately the prevalence of anti-vaxers on the internet is equivalent to the quantity of porn on the internet... I'm just curious as to how many actually DIE from it.. (If they died from the flu shot there is no way they would survive an influenza infection!) [[Special:Contributions/199.19.248.20|199.19.248.20]] ([[User talk:199.19.248.20|talk]]) 05:50, 22 April 2016 (UTC)
Revision as of 05:50, 22 April 2016
Welcome to the science section of the Wikipedia reference desk.
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.
If you mean for "small production runs", then it really depends on a lot of factors. If you need literally one circuit board and have access to a CNC machine, it will probably be quicker to use that. But if you need 20 boards, it might be quicker to print all 20 and etch them in one go than to mill 20 boards on the CNC machine. Secondly, depending how "automatic" your CNC machine is, starting the run and letting it go "overnight" for example, to mill 20 baords will be a lot "quicker" for you (counting only your labor time) as compared to the time and effort required to set up a chemical etching batch and the clean up etc involved, even if the end result will finish "sooner", so which do you prefer? Vespine (talk) 02:21, 18 April 2016 (UTC)[reply]
Just thought of another significant factor to consider is that chemical etching will not drill your board for you. So if you have a lot of through-hole components, manual drilling can be very time consuming and also introduce a significant chance of making a "mistake" potentially wrecking a board. Presuming the CNC machine can also drill the holes, but I'm pretty sure that's almost a given. Vespine (talk) 03:52, 18 April 2016 (UTC)[reply]
Just in the last year 3D printing of multi-layer circuit boards has got good enough to be used for fast prototyping or small runs and one can buy machines to do it. Dmcq (talk) 11:26, 18 April 2016 (UTC)[reply]
When using Windows and your computer crashes and you have to reboot:
When it comes to the screen where you choose to logon or restart or shutdown, should you restart so it shuts down properly and restarts again, or just logon? Thanks. Anna Frodesiak (talk) 08:11, 18 April 2016 (UTC)[reply]
It actually depends on what caused the computer to crash in the first place. Sometimes a proper restart is beneficial, while in other circumstances it doesn't matter. 81.132.106.10 (talk) 09:55, 18 April 2016 (UTC)[reply]
Newer versions of Windows (XP and after) recover better so that logoff and log on clean up a lot. But if in doubt, reboot, because Windows probably needs a reboot twice a month anyway to sort out installs and other problems. Graeme Bartlett (talk) 09:59, 18 April 2016 (UTC)[reply]
@Anna Frodesiak: for future questions, the computing, rather than the science desk might be the better place to ask such questions.
@Anna Frodesiak:, when staring an operating system, serives are started an open files like databases or logfiles. When not shuting down properly, these files are not finished in wirting and the filesystem needs to synchronize all copes of it's tables of contents. Windows writes a copy of it's configuration, called the registry when logging on. In the start procetude, immedialtely after die BIOS, Windows listens for a key like F8 oder the spacebar. It allows the user to boot using the last known good configuration. This is the recent copy taken after the last logon. When updates were or other software was installed, those settings were lost, but the files are still stored on the drive. A resinstall of that software fixes any problems, if the installer works propperly. Upgrades may be a problem, due an old configuration ist applied to the new file versions. When using an autologon on windows, the last known good configuration is not possible, due being overwritten in the start procedure. --Hans Haase (有问题吗)22:05, 20 April 2016 (UTC)[reply]
I could get why the flow of current exist only for a short time as said in the video Principles of Electricity when we connect two different beakers that have metal strips immersed in them using a wire.The reason is the electrons from the zinc electrode goes through the wire to the copper electrode.But I couldn't get why there is a continuous flow of current when the beakers are joined together and why the electrodes(zinc and copper) become negatively and positively charged.Could anyone help me.JUSTIN JOHNS (talk) 09:01, 18 April 2016 (UTC)[reply]
Recall that when the zinc strip first entered the acid (at 6:01 in the Principles of Electricity video) some zinc atoms went into the solution, leaving their electrons behind so the zinc gained a certain negative charge (more so than the copper strip which being "less negative than" is the same as "positive relative to" the zinc). The flow of electrons stops when electrical balance is reached (at 6:18) where the solution is more positive than the zinc. However when the beakers are joined, the solution around the zinc receives electrons from the solution around the copper. The continuous flow of electrons from zinc to copper is exactly matched by a continuous flow of electrons through the solution in the opposite direction.
The linked video reflects its date, which was the end of WW2, when it teaches the Bohr model of the atom and mentions "the 92 known chemical elements" that seem to conclude with Uranium (number 92). In fact Neptunium (number 93) had just been isolated in 1944 and Plutonium (number 94) had been isolated in 1940, but wartime secrecy prevented its anouncement until 1948.
The video is not specific about the "chemical solution" involved, in fact a variety of soluble salts, acids or bases dissolved in water give an electrically conducting solution that works as an electrolyte; nor does it explain that copper, zinc or other metal electrodes will be negative or positive relative to one another depending on their relative electronegativities. AllBestFaith (talk) 11:11, 18 April 2016 (UTC)[reply]
Could you explain a little bit more about "The continuous flow of electrons from zinc to copper is exactly matched by a continuous flow of electrons through the solution in the opposite direction." as you have told.I couldn't really get that sentence.JUSTIN JOHNS (talk) 11:16, 18 April 2016 (UTC)[reply]
Your video is so out of date that it is leading you down the wrong track completely. It is now generally accepted that there is no flow of electrons through a wire when an electric current passes along it: it is the charge which flows, not the sub-atomic particles. If you want to know what electricity is and how it works, look at something up to date. 81.132.106.10 (talk) 11:50, 18 April 2016 (UTC)[reply]
Please ignore the above comment. Electric current really is a flow of subatomic particles and this view hasn't changed since 1945. There is nothing wrong with the video, and it even states that its picture of the Bohr model is only a symbol and not what an atom really looks like. --Heron (talk) 19:47, 18 April 2016 (UTC)[reply]
It's not that the electrons travel fast. It's that the movement of one near the end of a conductor displaces an adjacent one, which displaces an adjacent one, etc, etc. The effect is that an electron at the far end is displaced very rapidly. The movement of each individual electron is quite slow. Kind of like the water in a garden hose. When the tap is turned on, water flows out immediately but the water at the tap takes a few seconds till it flows through. Akld guy (talk) 09:06, 19 April 2016 (UTC)[reply]
The internal voltage would not be external, so the included battery / cell provides the energy for the current. However this will not last forever as the chemical energy will be drained. Another way is to have a continuously variable magnetic field threading through the circuit. Unfortunately we cannot make a magnetic field that increases forever, so it is much more common to use a variable field and get alternating current. Graeme Bartlett (talk) 09:40, 19 April 2016 (UTC)[reply]
Do you mean to say that the current will last only for a few seconds since it stops when the all the electrons from zinc rod are transfered to the copper rod?Can we make the process continue forever by using a salt bridge or any other solution?JUSTIN JOHNS (talk) 09:53, 19 April 2016 (UTC)[reply]
A zinc battery may last for quite a few days until all the zinc is dissolved. If you want it to keep going you need a continuous supply of material. This can happen in a fuel cell. A fuel cell could use hydrogen and oxygen to make electricity and water. Graeme Bartlett (talk) 10:38, 19 April 2016 (UTC)[reply]
The reason why it seems like so little happens when an EMF is applied to an open circuit is that it takes a really, really small movement of charge to make a big difference in voltage. How much exactly depends on capacitance, but let's put it this way: one mole of electrons, as might be generated from a molecular-weight's worth of grams of some substance giving up or accepting one electron, contains a faraday unit of charge (Faraday constant), i.e. more than 100,000 Coulombs. And the largest usual value for a capacitor, according to our article, is about 1 mF = 1 mC of charge moved / volt of difference. Electrochemical reactions typically are on the order of a volt, so that means that with good technology you might make a system where you can move 1/100,000,000 of a coulomb of charge before the voltage that creates puts a stop to it, or maybe consume about one millionth of a gram of some material with MW 100. However, there are no capacitors described in this circuit, and so we're looking at parasitic capacitance, less than picofarads, which is to say, a billion times less than that. So unless I fouled up in my math/logic (very possible) I'm seeing we usually expect something on the order of a million billionth of a gram of the battery's substance to get used up in order to create enough of a charge difference to prevent any more from reacting. Wnt (talk) 11:30, 19 April 2016 (UTC)[reply]
Maybe a useful analogy is a metal pole. If you poke on something with the metal pole, you know that the far end would not put any pressure on it unless the metal atoms were being pressed together by the force of your thrust. But you certainly can't *see* the compression; and what's more, you have no real idea how much the pole compresses per force applied, yet it has no practical effect on how much force you put on the far end unless it's practically a wet spaghetti noodle. Wnt (talk) 11:35, 19 April 2016 (UTC)[reply]
The video Principles of Electricity did not point to the impedance or internal resistor of a power source. Batteries do not contain supraconductors. Also the chemical process in the battery is limitted. Depending on the load, the voltage of the source dropps. On a constant load the voltage also keeps constant while the source delivers energy. During this time a continuous flow of electric current is present. It changes when to load is beeing changed or the battery gets empty. --Hans Haase (有问题吗)22:54, 20 April 2016 (UTC)[reply]
Why aren't there fungi that are sexually transmitted?
Parasites, viruses, and bacteria seem to be the main agents of STDs. What about fungi? Why aren't there fungi that are sexually transmitted? 140.254.77.156 (talk) 17:25, 18 April 2016 (UTC)[reply]
This is pretty much semantic. You can get lice from someone else's towel, or a cold from kissing your girlfriend. Most things like C. albicans can be sexually transmitted, but they are not exclusively so, nor primarily treated as if the partner may also need treatment. I.e, chaste virgins can still have yeast infections. μηδείς (talk) 21:05, 20 April 2016 (UTC)[reply]
Raising chickens
If you put one rooster with ten hens in a coop, then would they reproduce? Can you safely put two or more roosters in one coop, or will they become aggressive and territorial? 140.254.77.156 (talk) 17:40, 18 April 2016 (UTC)[reply]
You need to be careful putting a stranger rooster with an established group of hens. They sometimes gang up on him and attack - thought to be reason behind the phrase "hen-pecked". I would strongly advise against putting 2 roosters together - They will almost certainly fight, perhaps fatally. DrChrissy(talk)17:46, 18 April 2016 (UTC)[reply]
Some roosters might get along, others might not. No simple answers.I don't think this is something that there are generally applicable answers for. There's just far too much lore and science of chicken rearing to cover in a short post, but I'll sketch out some ideas and provide some refs that will help. For the breeding - it depends on how happy they are, what their lodgings are, what time of year it is, all sorts of things. For roosters fighting - it depends a lot on how much space is available (to roost, to nest, to forage), and likely what breed. Lots of other factors too (age at introduction, time spent in coop, etc.) Some chickens are more territorial than others. If you want to raise chickens, I suggest they start by reading a book, something like this [1]. Also you can read and post at a chicken-specific forum, like this one [2], or this subreddit [3]. Here [4] is the WikiHow category on chickens, and here [5] is a wikibook on raising chickens, both of those together will be a decent (free) primer, but raising chickens is also something that just requires some practice and experimentation to get good at. Finally I've WP:OR seen at many multiple rooster set ups in back yards; it can be done without aggression if there is enough space and you have the right breeds. SemanticMantis (talk) 18:34, 18 April 2016 (UTC)[reply]
How hard is it to change fields within engineering as a graduate? For example if your original major was in civil but your thesis was related to biomedical but you now work in civil engineering project management whilst volunteering for a mental health charity. How hard would it be to get into biomedical engineering then? 2A02:C7D:B907:6D00:A568:CD48:3581:1FB1 (talk) 20:22, 18 April 2016 (UTC)[reply]
It depends, particularly given your "as a graduate" caveat. First, how much do the two disciplines have in common? For example, here's the current plan of study for a B.S. in civil engineering from my college. Note that the majority of the coursework for junior and senior years are prefixed "CE". Someone changing over from electrical engineering would have none of those courses in their regular plan of study . Even the "technical electives" probably wouldn't permit crossover from one to the other (similarly, your "civil engineer with a thesis in biomed" is highly suspect, even as a thought experiement). "As a graduate", though, makes for a different question. If you're talking career, then it's a matter of "can you pass an interview?" The precise prerequisites are as varied as the jobs in question, and much of the matter is now a matter of your abilities as a candidate rather than your paper qualifications. Plenty of people are working in engineering fields for which they do not have the specific engineering degree. — Lomn20:53, 18 April 2016 (UTC)[reply]
In the U.S., Engineers generally need to pass two exams to be fully practicing engineers: the general Fundamentals of Engineering Examination, passed shortly after one graduates with an engineering degree from college (university), and a second Principles and Practice of Engineering Examination which is specific to the engineering discipline you are working in. Hypothetically, one could (on their own) learn what is needed to pass a second PPE exam, and simply take the second exam to be qualified to work in the new discipline, I suppose. I'm not sure how common or feasible that is, generally you're employed in a specific field, and work as an unlicensed "apprentice" before taking the PPE exam, since your on-the-job training generally prepares you for taking the PPE. --Jayron3201:06, 19 April 2016 (UTC)[reply]
Yeah, the relevance of professional engineering licensure is highly dependent on both field and role, and "unlicensed apprentice" misstates the nature of a large portion of engineering work. The distinction is (within the US, at least) one of whether you are certified to sign and seal documents for engineering work that does not involve interstate commerce. Lack of licensure does not prohibit one from performing the work, nor does it prohibit one from signing and sealing in cases where the work is interstate in nature (see engineering licensure in the US with regard to automotive and other applications). So no, the FE/PE is not a general requirement to be a fully practicing engineer, but rather a potential requirement for a narrowly-tailored area. — Lomn15:41, 19 April 2016 (UTC)[reply]
Easy. YOU are what matters. Not whichever papers you chose at uni. I've designed straw processing gear, crankshafts, undersea monitoring systems, steering systems, yacht hulls, electronic controllers, and every bit on the dirty side of cars. And buildings. Greglocock (talk) 03:55, 19 April 2016 (UTC)[reply]
Absolutely. We could also try extracting brains and testicles from trolls for the same purpose, but I fear the yield would be disappointing. Greglocock (talk) 03:16, 19 April 2016 (UTC)[reply]
Stopping to reflect for a moment, this could be the basis of a revolution for Wikipedia. Jimbo could set up a section within the WMF to market troll bile - and not just any troll bile, but Grade A Encylcopedic Troll Bile, the bile built on the sum of human knowledge. Profits from the sale of this ultra-rare product could be use to provide 5-star holidays for deserving Wikipedians. Bile production could always be increased to meet demand by showing trolls diffs of article improvements, and Wikipedia trolls should be a particularly rich source. EdChem (talk) 08:00, 19 April 2016 (UTC)[reply]
It certainly would do nothing for the energy shortage - liposuction is a surgical process, and all of the technology involved is likely to consume more energy that you could get from the fat removed. 81.132.106.10 (talk) 11:12, 19 April 2016 (UTC)[reply]
Body mass v O2
In general, do animals(of the same species) of a greater body mass use more oxygen (and excrete more CO2) than those of a lesser body mass?--178.99.232.11 (talk) 00:45, 19 April 2016 (UTC)[reply]
Why do Sodium cation (as well as cautions of all other alkali metals) have higher second ionisation enthalpy when compared to the first ionisation enthalpy of noble gases, though both have same electronic configuration, i.e. M+1 cation and ground state noble gases have similar electronic configuration? Eg: IE2 of Na is 4562kJ/mol while IE1 of Ne is 2080.7kJ/mol.
Sodium has a higher charge on its nucleus compared to neon. And to take a second electron off sodium, you have to pull it away from a Na2+ ion, which is harder than separating it from Ne1+. Graeme Bartlett (talk) 07:38, 19 April 2016 (UTC)[reply]
The sodium cation has a higher effective nuclear charge than the neon atom, thus a greater Coulombic attraction to the outermost electrons and a smaller radius. This greater attraction must be overcome in the second ionization, which will thus require greater energy. EdChem (talk) 08:02, 19 April 2016 (UTC)[reply]
What did DSPs like AT&T DSP1 (1979), Altamira DX-1 (1980s) TMS32010 (1983), AT&T DSP16A (1980s), Motorola 56000 (1986) cost like 2 years or so after their introduction? Would they or the NEC µPD7720 been capable of processing realtime Trellis encoding using a 3.3 kHz bandwidth? What would a suitable A/D + D/A cost at the same time, assuming a required 26.4 kHz sps? Bytesock (talk) 16:06, 19 April 2016 (UTC)[reply]
The TMS was of the order of a hundred bucks, in 1986, in the UK, from memory. I don't know what trellis encoding is and don't care to find out. Greglocock (talk) 01:57, 20 April 2016 (UTC)[reply]
If a healthy young person with good nutrition suffers an occasional broken bone, will that tend to help keep calcium levels in bones higher?(Not just in the bones that were broken, but others, such as vertebrate and so on.)I was thinking that after a break, hormones might be released encouraging calcium throughout the skeleton. 144.35.45.57 (talk) 16:17, 19 April 2016 (UTC)[reply]
Why do Neisseria gonorrheae and Chlamydia trachomatis infect together?
I've read that people who get gonorrhea also get infected by chlamydia. Why do those diseases and agents go together? Is there a relationship between the two types of bacteria? 140.254.77.233 (talk) 17:36, 19 April 2016 (UTC)[reply]
I will leave it for others to answer as to whether having one disease makes one more vulnerable to infection with the other. However, note that if transmission by both are caused by the same behavior, you would expect a correlation from that alone. For example; smoking, alcoholism, and drug abuse are often correlated because the same risk-taking behavior (in order to alter one's mood) are present in all cases. StuRat (talk) 17:51, 19 April 2016 (UTC)[reply]
Sorry no ref, and sorry if this is TMI, but: If the genital skin or mucous membrane is compromised in any way (e.g. a lesion or open sore), then there is a direct route into the bloodstream for another infection. So a chancre (a classic symptom of syphilis) would logically increase the risk of acquiring e.g. chlamydia. Carbon Caryatid (talk) 18:45, 19 April 2016 (UTC)[reply]
To further what the previous poster wrote the HIV#Origins article has this section: Specific proposed high-risk transmission channels, allowing the virus to adapt to humans and spread throughout the society, depend on the proposed timing of the animal-to-human crossing. Genetic studies of the virus suggest that the most recent common ancestor of the HIV-1 M group dates back to circa 1910.[1] Proponents of this dating link the HIV epidemic with the emergence of colonialism and growth of large colonial African cities, leading to social changes, including a higher degree of sexual promiscuity, the spread of prostitution, and the concomitant high frequency of genital ulcer diseases (such as syphilis) in nascent colonial cities.[2] While transmission rates of HIV during vaginal intercourse are typically low, they are increased many fold if one of the partners suffers from a sexually transmitted infection resulting in genital ulcers. Early 1900s colonial cities were notable due to their high prevalence of prostitution and genital ulcers to the degree that as of 1928 as many as 45% of female residents of eastern Leopoldville were thought to have been prostitutes and as of 1933 around 15% of all residents of the same city were infected by one of the forms of syphilis.[2]
Thus correlating statistics but not necessarily causal, may come from opening up infection pathways or weakening the immune defense. So the population may first experience syphilis, HIV and say TBC in that order.
I see, so they just look for temperature differences, and assume that means moisture. Seems rather iffy, as things like a hot water pipe may be hotter than the surrounding area whether they have a leak or not. StuRat (talk) 23:17, 19 April 2016 (UTC)[reply]
Yes, Stu. They're scammers selling this stuff to some poor idiots. So next time you have a water leak make sure the plumber rips your home apart until they find the hidden leak.--TMCk (talk) 00:49, 20 April 2016 (UTC)[reply]
Is there any scientific way to detect hidden mould? Toxic mould should be a worry for many households. If only there existed a machine that detected all known allergens! Sandman1142 (talk) 12:26, 20 April 2016 (UTC)[reply]
I know I can smell it, so a trained mold-sniffing dog ought to be much better at it. Of course, there would be health risks for the dog. StuRat (talk) 17:34, 20 April 2016 (UTC)[reply]
What line coding do modern harddiscs use?
Is it still magnetic S-N N-S polarity reversal and the pulse that it causes which is then coded according to some scheme that is used in modern harddiscs? And what coding scheme is used? ie line codes. Because MFM and RLL are most likely no longer used for that purpose.. Bytesock (talk) 21:17, 19 April 2016 (UTC)[reply]
Well, social worker is a protected title in England - one has to have a recognized professional qualification and be registered with the Health and Care Professions Council, see here for some more info. A support worker does not have to have the qualifications and level of registration, and is likely to be lower paid, work longer and more anti-social hours, and be more likely to be assaulted in the course of their duties. DuncanHill (talk) 22:45, 19 April 2016 (UTC)[reply]
Is there a *guaranteed* way to ensure that a person who already got an orchiectomy *doesn't* have *any* extra testicles?
Biology comes with few guarantees. After all, the extra testicle might (astronomically unlikely) be located in a teratoma or a parasitic twin, in a place where you would not expect to find it, and where it does not release sperm to the outside world. The person might also have a condition that prevents testosterone production, in which case you wouldn't find that hormone in blood work. (AFAIR there's also a lower limit of sensitivity because it can be produced elsewhere) Also other markers like INSL3 ([6] may mention more, but I haven't looked through it carefully) This combination of circumstances seems unlikely but in biology there can always be some exception. Wnt (talk) 00:17, 20 April 2016 (UTC)[reply]
Hey, you wanted to ensure and that is one way to be sure. This is the Trump method of ensuring there aren't any hidden sneak testicles — he'll make there be no more testicles. Just wait till approx. thermal equilibrium and maintain the same till any reactions proceed to completion.. Sagittarian Milky Way (talk) 01:42, 20 April 2016 (UTC)[reply]
Come on, I was attempting humor more than political expression. It's a very silly topic (hidden sneak testicles). I'll keep political mentions out of the science desk though. (I can still mention anthropogenic global warming in an unbothersome manner, right? That's only political if you don't believe the consequences of the laws of physics) Sagittarian Milky Way (talk) 22:13, 20 April 2016 (UTC)[reply]
A pelvic MRI would likely locate any extra undescended testicles. EvergreenFir(talk) Please {{re}} 06
58, 20 April 2016 (UTC)
Only if you have a half decent technician looking at the results and they don't make a mistake. Even then, I would be reluctant to talk about guarantees particularly considering stuff like Wnt mentioned and the fact that the OP's history suggests by guarantee they mean they want 100% rather than a very very low likelihood of error. For a lot of it, the chance that the testis will actually produce functioning sperm that will be able to impregnate someone without medical assistance would seem to be very, very, very slim although I'd still be reluctant to talk about guarantees. I'm not even sure you could get some sort of written or implied guarantee from a medical professional since it's a fairly weird request but in any case, what that's likely to mean is they have a medical malpractice provider or whatever who'd provide you money if their guarantee failed. (Presuming the guarantee actually meant something.) Nil Einne (talk) 10:16, 20 April 2016 (UTC)[reply]
April 20
Why did "clean coal" turn out to be so slow and expensive to develop?
I understand that there are serious unknowns about carbon sequestration and "clean coal". But I have to admit - when I first heard of the idea, I assumed someone would have an existing coal plant, drill a deep hole (and frack it), set up a pump to compress the exhaust and drive it underground ... and see what happened. At least you would smell no pollution today. So why didn't this zero-generation version of the process happen? Wnt (talk) 00:03, 20 April 2016 (UTC)[reply]
My cynical mind says that "clean coal" is just a marketing canard created (or rather repurposed) by the coal industry to keep coal burning alive longer. While it is not impossible to extract CO2 (and other pollutants - sulfur, particulates, ...) from flue gases, it's far from trivial to do so efficiently and cost-effectively - around 2/3rds is plain old nitrogen that needs to be separated out. If the proposed sequestration techniques for CO2 are long-term stable is a very much open question. In other words, without the atmosphere as a free dump, coal burning is unlikely to be cost effective. --Stephan Schulz (talk) 11:15, 21 April 2016 (UTC)[reply]
Honestly, I just pictured them taking the whole stack, nitrogen and other pollutants included, injecting it deep in whatever ground happened to be nearby, and hoping that/"researching whether" the carbon dioxide would react with something or at least dissolve into water long-term as it does in the ocean. Not saying this would be pretty or satisfactory ... just that it seems like a quick and dirty way to cap the stacks. Wnt (talk) 11:59, 21 April 2016 (UTC)[reply]
Coal is just not a very clean fuel in general. It has a whole host of things other than carbon that you need to keep from getting into the atmosphere (mercury is #1 on this list, but also other elements subject to emissions limits like arsenic and selenium) and it leaves ash full of all the non-combustible stuff that you have to get rid of somehow (which can be an environmental issue in itself, see Kingston Fossil Plant coal fly ash slurry spill for example). It's also less carbon efficient than oil or natural gas, each of which have much fewer of the other problems I mentioned with coal.
Compressing all of that gas and pumping it far away and deep underground is a hideously costly (and energy intense) process. You'd have to generate considerably more energy to cover the cost of sequestering the CO2 - and that just means that you have even more CO2 to sequester. Problems like that can very easily spiral out of control to the point that it becomes impossible to "win". One study showed that merely compressing the CO2 cost 25% of the power produced by the coal plant. If you also have to transport the compressed gasses to a convenient deep storage location, that number would increase substantially. Every ton of coal makes much, much more than a ton of CO2 - and if you aren't separating out the nitrogen and other gasses, it'll be immensely more than a ton. Now imagine the L-O-N-G coal trains bringing coal in - and imagine several times that number of waste gas trains hauling it away again! SteveBaker (talk) 05:27, 22 April 2016 (UTC)[reply]
There's been some concern in recent years about Teflon-based nonstick pots and pans, specifically with regard to the possible health effects of perfluorooctanoic acid (PFOA). In response, some people are returning to stainless steel.
But stainless has a severe sticking problem when new. To make it usable, one suggestion is to "season" the pot. You get it hot and add a bit of some high-smoke-point vegetable oil, swirl it around, let it cool, then wipe it out with paper towels rather than wash it. The oil leaves a residue on the pot, sort of a hard plastic, and now it's much less sticky.
The thing is, though, that seasoning is made of something. What, exactly? Does it contain, say, polycyclic aromatic hydrocarbons (PAHs)? Has anyone done a study comparing the possible effects of PFOA with whatever the more-whole-foodsy "seasoning" is made of? --Trovatore (talk) 05:54, 20 April 2016 (UTC)[reply]
Wait, what? Seasoning is usually only discussed for cast-iron cookware. Our article also mentions carbon steel, but outside of woks I don't think that's very commonly used. Stainless doesn't really take the polymerization layer because it's non-porous. See e.g. this thread [7]. I mean, sure, I guess you can do it to stainless steel, I just highly doubt the efficacy and that you're actually getting much of a persistent film. As for the new stainless being stickier when new - maybe you're just polishing your pots over a few uses so that they get smoother? But back to the question: the idea of seasoning is to cross-link and polymerize the oil. I cannot find anything scholarly on the health effects of this film. This [8] patent says that in addition to the polymer film, there is magnetiteblack oxide in/below the seasoning layer. The one thing I've heard recently about cast-iron cookware is the health benefits, e.g. here [9] and the lucky iron fish. Finally, PAH seem to only form in low-oxygen scenarios. So as long as you're seasoning in normal conditions, I don't think you'll be creating them from cooking oils. SemanticMantis (talk) 14:30, 20 April 2016 (UTC)[reply]
Hmm, well, the interblags seem to think you can do it. See for example here and search for the reply by "cheflars". I tried it and it worked. Admittedly it wasn't a well-controlled experiment, because that wasn't the only thing I changed — I also used less butter and lower heat. I'll try the seasoned pan with high heat and more butter just to see what happens. --Trovatore (talk) 18:13, 20 April 2016 (UTC)[reply]
Don't know about the salt's role in it (see your source) but one point is, to my knowledge, to prevent mineral and other deposits to build up as those add to the stickyness in all types of cookware.--TMCk (talk) 18:27, 20 April 2016 (UTC)[reply]
Oh, @Trovatore: I get it now, thanks. That person calls it "quick season", I think to differentiate it from what we do to cast iron. That method seems to be intended as a limited use "seasoning", which will need to be reapplied every few uses, in stark contrast to the hard shiny layer on my cast iron, which can't be done in a few minutes, and can last indefinitely with proper care use. So while you can do a similar thing to "season" stainless steal, it's rather different effect. SemanticMantis (talk) 18:50, 20 April 2016 (UTC)[reply]
OK, just tried it. I'd call it mostly a success. With the egg going into the soup of bubbling butter (with garlic and habanero slices there before the egg, of course), the egg white bubbled the way I remember it doing back when the pan was unbearably sticky. It came out with a little more difficulty than with the lower heat, but still I was able to get it out without breaking the yolk, which I never could pre-seasoning. Then cleanup without soap was also a little more challenging than the lower-heat trials, but I did manage.
Not claiming this is valid science, but taking the above observations together with the visual appearance of the film, I'm reasonably convinced. --Trovatore (talk) 18:44, 20 April 2016 (UTC)[reply]
Extra iron has health benefits for people who are iron-deficient, but it can be detrimental to the health of normal people, especially middle aged men and post menopausal women. Older people are advised to avoid using cast iron pots and definitely not to use iron supplements. [10]CodeTalker (talk) 16:53, 20 April 2016 (UTC)[reply]
You're right, the source doesn't specifically recommend against excess iron, it just shows that excess iron can cause bone loss. For more specific recommendations against iron supplementation, see [11], [12], [13]. CodeTalker (talk) 19:32, 20 April 2016 (UTC)[reply]
Restriction of supplemental intake makes of course sense but I was wondering about the "avoid cast iron pots" advise. How much iron would be absorbed by the food under normal cooking conditions?--TMCk (talk) 19:46, 20 April 2016 (UTC)[reply]
This article [14] references a 1991 study in Journal of Food Science that showed that spaghetti sauce cooked in cast iron absorbed 2 mg of iron per 100 g of sauce, and applesauce absorbed 6 mg. Given that 100 g is a pretty small serving and that the daily recommended allowance of iron for men is 8 mg, this seems fairly significant. CodeTalker (talk) 20:28, 20 April 2016 (UTC)[reply]
@CodeTalker: and @TracyMcClark and --TMCk: That result is not typical of cooking general things in cast iron, and that is even mentioned in the blurb linked. In more detail: tomato sauce is acidic, and will both break down the seasoning on the pan as well as etch the iron. Also, it is reported that the tomato sauce becomes darker colored than it would in e.g. stainless steel. For this reason, the general advice is to not cook tomatoes, lemon juice, vinegar, or anything else acidic in cast iron cookware. E.g. here [15] they say to "avoid overly acidic foods in our cast irons. On the same token, it’s best not to deglaze a cast iron with vinegar or wine". SemanticMantis (talk) 20:59, 20 April 2016 (UTC)[reply]
1) Ceramic coatings can provide excellent non-stick surfaces with no need to season. They are scratch resistant, but can crack.
2) This issue only comes up when cooking at high temperature, as in frying.[citation needed] Since this is unhealthy anyway, I've decided to cook at lower temperatures, such as boiling water. For example, I don't fry salmon, I boil it in soup. While I made this change for health reasons, a side benefit is that the pot is much easier to clean than a frying pan. StuRat (talk) 17:40, 20 April 2016 (UTC)[reply]
From our PTFE article: "While PTFE is stable and nontoxic at lower temperatures, it begins to deteriorate after the temperature of cookware reaches about 260 °C (500 °F), and decomposes above 350 °C (662 °F).[39] The degradation by-products can be lethal to birds,[40] and can cause flu-like symptoms[41] in humans. See polymer fume fever." StuRat (talk) 18:46, 20 April 2016 (UTC)[reply]
Frying or boiling salmon? <shudder> IMHO there's only one respectful way to treat a nice piece of salmon, and that's to broil it, gently, so it's still translucent in the middle. However canned salmon can be nice in a scramble, with capers. --19:17, 20 April 2016 (UTC)
It might be good, but it just seems like a waste of fresh salmon. I bet you couldn't really tell the difference if you used canned, except for the spines, which in my experience soften in the cans to the point that they're harmless. Just like you don't use top-shelf whiskey for a Manhattan. --Trovatore (talk) 05:27, 21 April 2016 (UTC)[reply]
I eat salmon because it's healthy, and I get it for $4 a pound, eating a $1, 4 oz portion with each meal. So, I'm not exactly breaking the bank. StuRat (talk) 15:07, 21 April 2016 (UTC)[reply]
And then it goes on saying: "Meat is usually fried between 204 and 232 °C (399 and 450 °F), and most oils start to smoke before a temperature of 260 °C (500 °F) is reached,..."--TMCk (talk) 19:13, 20 April 2016 (UTC)[reply]
Right, and if the pan was fully submerged in oils with a low smoke point and kept below that smoke point, that would keep it at a safe temperature. But, the pan only has oil in the bottom, allowing the area above the oil to get hotter from heat that rises around the edge (especially on gas stoves on high) and higher temp oils may be used, and the pan may be left on the stove too long and smoke or even burn dry. (This can also happen when boiling in water, but I use a microwave oven to boil my salmon chili, which has a timer so I don't have to worry about that.) StuRat (talk) 00:41, 21 April 2016 (UTC)[reply]
It was rare for me, too, but just a few times destroying a pan and having to open all the windows in January to air out the smoke were enough for me to avoid it. I never understood why stove burners don't have timers on them. It would be trivially easy on an electric stove, and just a bit harder for gas. StuRat (talk) 02:53, 21 April 2016 (UTC)[reply]
This seems like a backward attitude. Undeniably kitchen fires happen and people die from it. A timer, or a simple device to check for the extraordinary heating that occurs in a dry pot rather than a wet one, or a physically linked smoke analyser (I won't say "detector" because I mean something that responds to serious and user-configurable amounts of smoke only, not a bureaucratically defined object), or even a photodiode looking for the flicker of fire might all potentially offer some protection (but I think the thermometer is the most practical idea). I feel like any good, obvious idea doesn't get done until there is a way to link it up to the Internet and have the NSA tracking your every move, at which point they say woo-hoo, we'll give you some features you wanted for 50 years, and all you have to do is agree 1984 is a damn good idea! Wnt (talk) 12:08, 21 April 2016 (UTC)[reply]
I agree (except for the NSA part). Cooking methods that don't shut off automatically should be banned, as the risk of fire is obvious. StuRat (talk) 15:11, 21 April 2016 (UTC)[reply]
@Stu: Put your stove on a timer or even better, turn off your electricity and ban every little thing that could pose ANY risk at all but don't try to restrict everybody else just to protect the fools and the overly scared.--TMCk (talk) 16:00, 21 April 2016 (UTC)[reply]
My stove is gas, and, as I already stated, I've solved the problem by using a microwave to cook. I also have a portable electric convection oven, with a timer, for foods that require browning. StuRat (talk) 16:50, 21 April 2016 (UTC)[reply]
Question: I don't know, but I'm thinking stainless steel pots also work by passivation of a mostly-not-chrome metal into a mostly-chrome surface. Does the chrome have different adhesive properties than the steel? (I easily picture the vegetable oil works short-term but I don't know whether it can account for the long-term change) Wnt (talk) 12:09, 21 April 2016 (UTC)[reply]
Here's a nice (promotional) write up about passivation of stainless [16] as an intentional industrial process increase natural passivity. However here is a great documentary showing that stainless steel is also self-passivizing. The relevant bits start around 2:40 but the whole thing is probably worth it for the narrator, graphics, and music :) As for friction/adhesion, it seems chrome oxide is slipperier than steel, and "The coefficient of friction of hard chromium against hard metals are generally the lowest of any electrochemically deposited coatings." [17]SemanticMantis (talk) 15:03, 21 April 2016 (UTC)[reply]
The answer in general is: the more you sweat (like an athlete who trains regularly), the more salt you need in your diet, compared to someone who does not sweat a lot. However, I'm not sure that people in hot climates generally sweat a lot more than other people, people who live in hot climates are more acclimatized to the heat, wear less clothes, stay out of the sun, avoid strenuous activity during the hottest parts of the day, etc... Vespine (talk) 06:31, 20 April 2016 (UTC)[reply]
Hi Vespine. That doesn't quite answer the question. Let me be specific: Me. I live in Haikou. It's hot in the summer. I sweat a lot because it's broiling hot. I eat lots of salt year round. Is the salt I eat in the summer less harmful than the salt I eat in the winter. Anna Frodesiak (talk) 07:22, 20 April 2016 (UTC)[reply]
A tad disingenuous, maybe? For decades we've all been told of the health risks of too much salt. With all the conflicting health advice we get these days, it's not surprising if not everyone is up with the latest breathless revelations. And they may still not be up to speed by the time the next contradictory report comes along, restoring the status quo. Lesson: If you stay out of touch for long enough, you'll get back in touch again. Nothing new under the sun. -- Jack of Oz[pleasantries]09:53, 20 April 2016 (UTC)[reply]
Admittedly, it seems almost like a fringe opinion. Nonetheless, I think it deserves consideration! The central issue there is whether the health effects of salt represent causation or correlation. Personally, I am biased because of an incident that happened in my 20s. Over a few weeks I kept feeling more and more desire for salt, yet found it less and less satisfying ... eventually the salt even seemed to have a sour undertone, and I started thinking something was wrong with it. After some false ideas, I happened on a potassium salt substitute and it was just ... heavenly. Exactly the flavor I was looking for, extraordinarily satisfying, and that was the end of it. And so I wonder whether people who consume more salt are simply hungry for potassium but eating the wrong thing, and whether then it might make more sense to focus on potassium supplementation than cutting sodium. (A touch of epsom salt every now and then feels very nice to me also) Wnt (talk) 11:52, 20 April 2016 (UTC)[reply]
I don't believe your case is typical. I find potassium chloride to be repulsive (only acceptable in small amounts) , and absolutely hate it when something sold as "low sodium" has that added in it's place. I just want low sodium foods with nothing else added. Also, if you find regular table salt sour, that might be the added iodine. You can buy noniodized salt, but beware that you might not get enough iodine then. StuRat (talk) 17:28, 20 April 2016 (UTC)[reply]
@StuRat: Oddly enough, that was the first thing I tried during that period - but the fresh container of non-iodized salt seemed exactly as sour and unsatisfying. The sense of sourness went away almost entirely once I had balanced myself out a bit with potassium, though I am faintly aware of it to this day if I really think about it. The salt I use routinely is a "salt lite" (50% potassium 50% sodium); the two flavors complement each other well and it comes in bigger cheaper handier containers. The way I think of it, "salt" is a generic term for a mixture of ions, and sodium sits just a little to the sour side of the spectrum within it. Wnt (talk) 01:08, 21 April 2016 (UTC)[reply]
That's probably good, since most people get too much sodium and too little potassium. You might also try high potassium foods, like bananas. StuRat (talk) 01:14, 21 April 2016 (UTC)[reply]
Eventually, yes, but the problem is that the elevated sodium level can cause damage until it's corrected. Just a bit of damage each time, to be sure, but it's cumulative. StuRat (talk) 01:12, 21 April 2016 (UTC)[reply]
In general, people will adapt to heat, and after a few days or weeks, will excrete less salt with the sweat. So yes, you may need more salt intake in hotter climate, but the effect will be mostly temporary, and will be less than naively expected. --Stephan Schulz (talk) 13:11, 20 April 2016 (UTC)[reply]
That makes sense, and is what I would have guessed. But I don't know for sure, and I have no refs to back this idea up. Anyone else want to try to find refs along these lines? SemanticMantis (talk) 14:10, 20 April 2016 (UTC)[reply]
Ok this [18] is highly relevant (but paywalled), says "the data are best explained in terms of an active regulation of sweat composition" -- but that is with regard to exercise at different temps, not acclimatization effects. Here are some freely accessible papers: this one [19] is about sodium intake and sweat composition, and this [20] is about sodium secretion and re-absorption more basically. Note the last one is from 1965, and the first link (1982) may supercede some of the notions presented in the earlier paper. SemanticMantis (talk) 16:52, 20 April 2016 (UTC)[reply]
OR: I have sodium sensitive hypertension, as do my brothers (but oddly, neither of our parents). I've come to the conclusion that it's not so much sodium I consume, per see, but how much I consume relative to the amount of water I consume. So, if I drink more water (which I will need to, if sweating profusely), then I can consume more salt. StuRat (talk) 17:23, 20 April 2016 (UTC)[reply]
This entire thread seems like medical advice to me, which we don't provide here. I'm not bold enough to remove it myself, but perhaps someone else is. --69.159.61.172 (talk) 19:28, 20 April 2016 (UTC)[reply]
We have an unofficial guideline called Kainaw's criterion [21]. I don't see any response that says anything about treatment, medical diagnosis, or prognosis. What I see are references to WP articles and scholarly literature about the human body and biological processes. We should not give medical advice, but we are allowed to give biological information. If you do see a response that offers suggestions for treatment, diagnosis, or prognosis, please do remove them. SemanticMantis (talk) 20:09, 20 April 2016 (UTC)[reply]
This is certainly not medical advice to me. I don't give a hoot about salt. This follows an off-wiki discussion about how the body works. I said I'd post here and ask so I could say "Ha!" to someone.
In a nutshell, what I am asking is if salt does do some harm to arteries or kidneys etc. before it is peed out, is it disposed of better or earlier or less harmfully by sweating?. I mean, does it never see kidneys on the way. Do you see what I mean? And thank you all for the good information (so far). Anna Frodesiak (talk) 01:31, 21 April 2016 (UTC)[reply]
A big issue I have with the Big Bang is that more and more stuff happens the further back you look. It gets ever hotter, ever denser the closer you go to the moment. So if you look at something like the logarithm of time, maybe that makes more sense as "true time" that things happen in than the non-logarithmic form we use, even though the normal form of course is proportional to specific physical processes. And if you look at time in smaller increments, then the velocity of anything less than lightspeed is less (same way as if you double a velocity, it never goes over lightspeed). And distances are greater, since that means light travels more increments of time to go between two given points. And particle lifespans are greater, and so forth. For much of the life of the universe it might even have had roughly the same size by that criterion. What you lose is the invariance of atom size - obviously, near the Big Bang they would be immense, the size of the universe even, but kept shrinking. So I continue to wonder, if you look at the universe in this sense, can you see it as something with an infinite history, and potentially a warm future (though one with really teeny atoms with generally very short half-lives!)? In any case, it illustrates the notion that you may simply not have a continuum of time going before the Big Bang at all. Wnt (talk) 01:53, 21 April 2016 (UTC)[reply]
I would not rule out the possibility that time itself was created at (near?) (just before?) the beginning of the big bang, and that the concept of "before the big bang" has no meaning. I also would not rule out the possibility that the answer to the ultimate fate of the universe question involves time itself ending. When dealing with the unknown, it is risky to rule out anything without a sound reason for doing so.
Well, using log time sort of changes how you view the later eras also. Maybe in the cold dead corpse of the cosmos, as commonly portrayed, it takes a billion years for the same amount of stuff to happen as happens in a nanosecond today. And the universe is larger by about the same proportion. But if you use a correspondingly larger unit of time, then the universe seems about the same size with the same amount of stuff happening. It's just that it's a universe where atoms have gotten really tiny and their transitions absurdly high in energy, whereas maybe a thermal neutrino seems about the right size and stability for interesting chemistry to occur (I don't know this!) Wnt (talk) 22:39, 21 April 2016 (UTC)[reply]
It's difficult to understand this question, but I think you may be asking what the speed of galaxies and such is in the universe. Is this what you meant ? StuRat (talk) 01:55, 21 April 2016 (UTC)[reply]
Thanks, Alansplodge and Sagittarian! So, another instance of Twain's criticism being misplaced -- Hawkeye actually could see the nail at that distance, and while he could not hit it repeatedly as described in the book, he could cluster the shots in a nickel-sized area centered on it -- so Cooper exaggerated, but not by a whole lot (definitely well within the limits of legitimate hyperbole). 2601:646:8E01:515D:F88D:DE34:7772:8E5B (talk) 22:40, 21 April 2016 (UTC)[reply]
Does gravity slow down time sundial clocks?
I read that a clock on the top story of a skyscraper will tell time a little faster than a clock on the ground floor, because gravity slows down time, as Einstein’s General Theory of Relativity predicted. My first question is how can you tell that one clock is going faster than the other, as all local clocks will be affected by gravity?
My main question has to do with sundials. I am wondering if gravity would affect one sundial differently to another, that is, one sundial on the top floor, and one on the ground floor. Wouldn’t they both tell the same time, unlike the mechanical clocks next to them? Myles325a (talk) 07:40, 21 April 2016 (UTC)[reply]
The sundial at ground level will be fractionally behind the one at height - because the light from the sun will have taken very slightly longer to reach it. The difference, of course, will be way to small to be observed on something as inherently inaccurate as a sundial. 81.132.106.10 (talk) 09:57, 21 April 2016 (UTC)[reply]
Good question! This is in general an example of the difference between the local time and the time as determined from some external reference. No matter how massive the planet and how close you are to it, the sundial of course still goes around once a day. But ... the time dilation from being in heavy gravity is still real. So the day itself must appear shorter from the perspective of the person near the planet! In much the same way, the days of other planets, the years of other planets, the periods of pulsars etc. all have to seem shorter. The key to trying to understand this is redshift/blueshift - as we perceive the light from deep in a gravity well, it is like a recording with all the playback sped up. And the reason for that is because, even though in a Newtonian sense we seem to stay the same distance from the sun, in relativity gravity is acceleration and we really are constantly being accelerated toward all the external sources of light! So we are constantly getting ahead of our default rest position of where we would be relative to the light if we were falling. (It is about at this point where my intuition has yet to be led...) Wnt (talk) 11:54, 21 April 2016 (UTC)[reply]
Canadian geese that travel in pairs
I often see Canadian geese travel in pairs or fly in V formation (if they are in a group), but mostly travel in pairs. I read on Wikipedia that geese form monogamous couples for life or until one partner dies. Do these geese use any cues to determine their sex? As far as I can tell, they all look the same to me. Do they usually come in pairs with one male and one female, or is it possible to have a pair with two males or two females? If a same-sex pairing does occur, do they engage in same-sex sexual activity together? 140.254.229.116 (talk) 13:20, 21 April 2016 (UTC)[reply]
First, they are more properly Canada Geese. Any old snow goose might be Canadian (due to where it was born), but "Canada goose" is the name for what you're talking about, Branta canadensis if you want to use the scientific name. They have lots of ways to tell what sex the other is, including courtship behavior, sound, and yes, even visual cues. They may all look the same to you, but individual birds have subtly different markings. Here [22] is a study that shows young canada geese can recognize siblings when they are only a few days old. Here [23] is a study that shows that canada geese can distinguish individuals by vocal call. As for homosexual pairings: that's not uncommon in Canada geese. See List_of_birds_displaying_homosexual_behavior, with a reference for B. canadensis. Here [24] is a whole study of male-male homosexual pairings in a different goose. I couldn't find one specifically on Canada geese, but most waterfowl will exhibit some same-sex pairing, especially in captivity or when sex ratios are skewed. If you're interested in diversity of pairing and mating in the animal world, I suggest the book Evolution's Rainbow[25] written by Joan Roughgarden, one of the current leaders in the study of evolution of social behavior, courtship and sex. SemanticMantis (talk) 14:44, 21 April 2016 (UTC)[reply]
For understanding why you can't tell Canada goose apart, but they easily can, see Out-group homogeneity for the general concept. In simplest terms, the more unlike you a group of beings are, the less likely you are to be able to know what cues are necessary to tell one individual from another. This is not a problem for members of said group. --Jayron3218:11, 21 April 2016 (UTC)[reply]
As for travelling in pairs or in larger groups, they travel in pairs over short distances (often walking), while they form up into flocks for longer flights, during migration. StuRat (talk) 14:58, 21 April 2016 (UTC)[reply]
Seismology patterns today
Well Ive been reading about increased seismic activity the last couple of years and, while no scientist by training, how does this stack up? Is there a source somewhere to indicate the average number/intensity/depth of tectonic movements?
also most earthquakes happen, obviously, beside plate boundaries, but why is there this outlier in OK? Is it increased fracking that I heard about?
Also Hawaii is slap bang (or thereabouts) in the middle of the most volatile plate, how does it, then, get that activity (volcanoes yes but earthquake)?
Sorry, this is very important, so please excuse the bold type: Yes, fracking and associated fluid injection can cause earthquakes, and is the causal agent for the recent sharp increase in earthquakes in OK. See this clear headline [26] saying "Injection wells blamed in Oklahoma earthquakes". See also this [27] 2013 review article published in Science, this [28] article looking at how to cope, and this [29] general assessment of fracking impacts, including pollution, global warming, earthquakes, etc. There's no dispute - fracking is bad for almost everything, except exploiting previously inaccessible petrochemical resources. SemanticMantis (talk) 16:35, 21 April 2016 (UTC)[reply]
I would say that fracking induces triggers earthquakes, as opposed to causing them. They are still caused by plate movements, it's just that fracking might trigger them earlier than they would have happened without it. Note that while only small earthquakes have been triggered so far, larger quakes are possible, too. StuRat (talk) 16:46, 21 April 2016 (UTC)[reply]
I am no seismologist, so I will defer to the fine folks at Science on this one. They say "Sharp increase in central Oklahoma seismicity since 2008 induced by massive wastewater injection" [30] -emphasis mine. Our friends at wiktionary say "induce" means "To cause, bring about, lead to" [31]. So you can say what you want, but I'll go with the experts here. Put another way: If your nemesis pushes you off a tall building and you plummet to your demise, feel free to blame gravity as your cause of death. Me, I'd say it was the one who pushed you. See also Proximate_and_ultimate_causation. SemanticMantis (talk) 17:05, 21 April 2016 (UTC)[reply]
A doctor can induce pregnancy without having planted the seed himself, though I wonder if an angry husband has ever misunderstood this point. :) Wnt (talk) 22:43, 21 April 2016 (UTC)[reply]
To directly answer the question about a "real-time source" of information on volcano activity:
One resource is the Alaska Volcano Observatory, operated by the University of Alaska, Fairbanks, in conjunction with the US Geological Survey. It principally monitors Alaskan volcanos; but they have a fascinating "mission control"-style room with a lot of experts and researchers who tend to pay attention to any activity worldwide.
Another great resource is the Hawaiʻi Volcano Observatory, which principally monitors the active volcanos in the main island of Hawaii. Both of these facilities have great websites and link to several other facilities of the US Geological Survey, among many other worldwide agencies.
If you should ever find yourself in Fairbanks, the AVO is sometimes available for tours. The Geophysical Institute coordinates activities and has special sessions geared towards physics researchers and for the generally-interested public.
The Hawaii Volcano Observatory has a public museum inside the Hawaiʻi Volcanoes National Park. Depending on your visit, the volcano activity may be observed remotely from that station - they have telemetry, video links, and loads of scientific data, much of which is also available at no cost via the internet at the park service's website and the Geological Survey's website; if weather and geological conditions are safe and legal, you can even get down to the lava flows.
As I live in an active seismic zone, and frequently find myself traveling unpleasantly-close to active volcanos, I keep the Earthquake Hazards Program website in browser's bookmarks so that I can check it daily. When there is notable volcanic activity, it is frequently accompanied by other seismic activity, and the earthquake page usually makes a note of it.
Not globally - like other random events, earthquakes tend to come in clusters, giving the impression of greater activity at certain times. If we're talking about induced seismicity, then if somebody starts to carry out deep wastewater injection on a large scale, you can expect small (and potentially moderate) earthquakes to follow. This effect has been known about for many years, ever since the Denver earthquakes[32]. Mikenorton (talk) 18:17, 21 April 2016 (UTC)[reply]
Classical momentum problem
Hello, I'm a first year physics student with no formal education on relativity, so forgive me if a fallacy in this problem involves using classical physics to solve it. This was just a thought that came to me when learning about modern physics (i.e., momentum and energy of light). Consider a beam of light being shone in the positive x-direction towards a mirror far away in space, isolated from any other body. The light beam has a momentum , and the mirror is at rest. Say that the light beam (which I can consider a photon) has an elastic collision with the mirror, and rebounds with momentum . The change in momentum for the photon is thus , and since the system is isolated, we would expect the mirror to end up with a momentum of . Yet, since the collision is elastic, then the change in (kinetic) energy is conserved, and since the energy of a photon is , we have . However, the kinetic energy of the photon did not change (frequency should still be the same, and it is still moving at the speed of light), implying , which means that despite gaining momentum, the mirror is still at rest! This seems to violate the conservation of momentum to me; the mirror did not gain speed, and it couldn't have gained mass... What's wrong here? Thanks for the help! 70.54.113.74 (talk) 19:15, 21 April 2016 (UTC)[reply]
The assertion that the photon's frequency is is unchanged is only correct if the mirror stays perfectly at rest. However, in reality it starts to move a little bit because of the collision, and therefore the frequency (and thus energy) of the photon changes due to the Doppler effect. - Lindert (talk) 19:29, 21 April 2016 (UTC)[reply]
(edit conflict) You are doing pretty well, but you messed up one of your assumptions. In a classical elastic collision (not involving light) you assume that energy and momentum are conserved and then solve for the two final velocities. In your case, you should assume that energy and momentum are conserved, and then solve for the final velocity of the mirror and the final frequency of the reflected photon. The rebounding photon only has the same energy is the mirror is infinitely heavy. For a normal mirror it transfers some of its energy to the mirror and hence the reflected photon is (slightly) less energetic than the incident one. Dragons flight (talk) 19:38, 21 April 2016 (UTC)[reply]
Our article on vasectomy cites this source that says that 1/2000 of the time the vas deferans can reconnect. I did not access the full text to see whether this is by the ends finding each other or by some other means. It is at least conceivable but astronomically unlikely that an extra testicle that never had a vas deferans nonetheless forms some kind of fistula with the severed end of a vas deferans after orchiectomy. On the other hand, it is also at least conceivable that the surgeon cannot count to two! The problem with this line of questioning is that you're getting into areas where things are so unlikely and involve such unlikely circumstances there's almost no chance of finding empirical data about what happens, and in biology there's no data that is not empirical. It is entirely possible that the same genetics that causes polyorchidism has an effect on the rate of vasectomy failure, for example, but nobody knows, because only a few people with polyorchidism ever had vasectomies and none of their doctors got together to do a study. Wnt (talk) 22:54, 21 April 2016 (UTC)[reply]
What's with the red displays in front of buses now appearing in NYC?
I see from The Real Hustle that the UK has similar buses. I find the letters displayed hard to read. Not sure whether my slight red-green color blindness is a factor. But surely there's a more pleasant color out there? 69.22.242.15 (talk) 22:19, 21 April 2016 (UTC)[reply]
Specifically, by "display" do you mean the destination sign (reading "M15 SOUTH FERRY")? As SMW says, it's orange. If you're red-green color-blind then you might not see that.
In my experience single-color LED signs of this type (not only on buses but in other places) are most often orange, although when they were a new thing, red was common. I just did some Google searches to try to find out why orange is so commonly preferred, but couldn't find anything. I think it's safe to say that most people find it more legible than red, and maybe it's just cheaper than another color such as white or green. --69.159.61.172 (talk) 04:37, 22 April 2016 (UTC)[reply]
Among hobbyists, red and green and yellow are typically the "cheap" LEDs while blue and white are typically considerably more expensive, for the equivalent "type" at least. I think yellow is simply the most visible and least "unpleasant' out of the cheap ones, I think green and red are unnecessarily saturated and more contrasted than yellow. Vespine (talk) 04:52, 22 April 2016 (UTC)[reply]
Red/Green colorblindness means that you can't distinguish red from green - not that any of those colors are indistinguishable from a black background. SteveBaker (talk) 05:09, 22 April 2016 (UTC)[reply]
Two Nostril questions
My Q is in two parts: a) Why do the human nostrils point downwards instead of forwards like lots of other anim,als?. b)I can breath freely using either nostril at the moment but some people say that nostril usage alternates from one to the other with one always blocked. Is that true if not/so, why/not?--178.108.238.49 (talk) 23:35, 21 April 2016 (UTC)[reply]
Regarding the down-facing nostrils, it is an evolutionary feature common to not just humans but all apes and Old World monkeys, see Catarrhini (as opposed to Platyrrhini, the New World monkeys). As such, this trait pre-dates bipedalism by millions of years. --Dr Dima (talk) 00:54, 22 April 2016 (UTC)[reply]
As to why this trait evolved we may never know, although people are always tempted to come up with "just-so stories" to explain the origin of various traits. One such just-so story is that humans have larger noses to warm up cold air or to filter out dust; yet proboscis monkeys have noses that would put any human to shame. --Dr Dima (talk) 01:04, 22 April 2016 (UTC)[reply]
The universe is thought to be one of three universes. Closed, open or flat. A closed universe involves gravity being to high, and the universe closing in on itself to a singularity. An open universe involves gravity being too high, where the universe will keep on expanding forever making things really far apart (If memory serves me right observations which have led to the idea of dark matter make this less likely). A flat universe is one where in the future it would (correct me if I am wrong) stop expanding somewhere in the future and not contract. In any case, the only possible universe where the universe could be exactly like today is in a closed universe, which would invariably be different. So to give you a short answer, no. JoshMuirWikipedia (talk) 02:18, 22 April 2016 (UTC)[reply]
Well, philosophically speaking there really isn't any very good reason why none of us will be around, apart from probability, but as time approaches infinity, even very low probabilities approach certainty. There isn't any very good reason why there couldn't be another universe where everything is exactly the same, except my hair is blond instead of brown. It might not be "THIS" universe, but "some" universe.Vespine (talk) 04:00, 22 April 2016 (UTC)[reply]
Entropy says "No". The entropy of the universe increases over time - so it can never return to a previous state everywhere. However, if the universe is spatially infinite (which is possible) - then small regions might turn up with precisely the same configuration of matter and energy as occurred trillions of lightyears away and billions of years ago might occur. Infinity is a large number! There are only just so many ways that the matter and energy withing (say) a cubic parsec can be arranged - and while that's an ungodly large number - it's not even close to infinity. So there must be repetitions of many (indeed infinite) numbers of cubic parsecs of space. So that one of them should happen to be identical to the cubic parsec we happen to be occupying right this instant seems pretty much inevitable.
So I believe that if the universe is spatially infinite - then the same situation will repeat itself for some small-ish regions of the universe - but it's impossible for the entire universe to repeat, no matter how long it lasts. SteveBaker (talk) 05:03, 22 April 2016 (UTC)[reply]
Note 3. means readings of clocks of ε' coach. "[" means left clock according picture (hind), "]" means right end clock (front). means readings of clocks of ε' coach seen from ε' coach (frame). We neglect time needed light to reach eye (there are no observers).
I am having a hard time finding a reliable source for this one.. "How many people die from the flu shot every year?" Such a simple inquiry... unfortunately the prevalence of anti-vaxers on the internet is equivalent to the quantity of porn on the internet... I'm just curious as to how many actually DIE from it.. (If they died from the flu shot there is no way they would survive an influenza infection!) 199.19.248.20 (talk) 05:50, 22 April 2016 (UTC)[reply]
Those are orange. Sagittarian Milky Way (talk) 23:15, 21 April 2016 (UTC)
![{\displaystyle \theta _{(t'=0),self}^{]}=0}](https://wikimedia.org/api/rest_v1/media/math/render/svg/ba99f2a71577155f9b467d49f8b5b4ffe0c1df11)
![{\displaystyle \theta _{(t=0)}^{]}=?}](https://wikimedia.org/api/rest_v1/media/math/render/svg/1089bf3e19ecbce47c6dd8c12f9b1cba5be5e800)
![{\displaystyle \theta _{(t'=L'/2c),self}^{]}={\tfrac {L'/2}{c}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/6c78e5793500a1045157ef401bd5746e9abaab84)
![{\displaystyle \theta _{(t=\tau _{1})}^{]}=\theta _{(t=0)}^{]}+\theta _{(t=\tau _{1})}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/0373ba0d868fa863bc1c307a7dd4b4be1aed740d)
![{\displaystyle \theta _{(t=\tau _{2})}^{]}=\theta _{(t=0)}^{]}+\theta _{(t=\tau _{2})}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c0c19360270323f34613184eee71166245fc6aaa)
![{\displaystyle \theta _{(t'=A),self}^{]}=A}](https://wikimedia.org/api/rest_v1/media/math/render/svg/be850716b2bc15aa8d48084229e4c3eeeadb7d22)
![{\displaystyle \theta _{(t=B)}^{]}=\theta _{(t=0)}^{]}+\theta _{(t=B)}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c38313a07b65f34fdfe39bc87b030805153588d7)
![{\displaystyle \theta _{(t=0)}^{]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/d8945a671c194b9d7b641a15aaed92752d7e1c9d)
