Wikipedia:Reference desk/Archives/Science/2017 May 8

= May 8 =

Astronomy / Calendar : Thirteen Groups of (Almost) Eight
What possible astronomical meaning or calendrical interpretation, if any, can be assigned to a structure containing thirteen groups of eight objects (of which two such groups might be slightly smaller, containing only six or seven objects each) ? Of course, one probable explanation would be the number of seven-day weeks in two years; however, the civilization which build the structure is known to have had a six day week, hence the dilemma. — 82.79.178.230 (talk) 08:13, 8 May 2017 (UTC)
 * Your question sounds like you're confusing astronomy (a discipline of physics, a body of knowledge based on application of the scientific method to elucidate knowledge about the universe) and astrology, which is bullshit. -- Jayron 32 14:45, 8 May 2017 (UTC)
 * Nothing of the sort. There is an ancient Carpathian sanctuary, consisting of four concentric circles. The meaning of the second and fourth circles are quite easily discernible; that of the first and third, not so much. There is also a smaller round sanctuary nearby, similar in structure (and, presumably, also in meaning) with the outer circle of the former. — 82.79.178.230 (talk) 20:57, 8 May 2017 (UTC)
 * Historically, most ancient civilizations conflated what we now call astronomy with what we now call astrology, and associated it/these with calendrical matters, so in a historical context the question is perfectly respectable. {The poster formerly known as 87.81.230.195} 2.122.60.183 (talk) 17:12, 8 May 2017 (UTC)
 * 13 Venus year equals 8 Earth year. Sagittarian Milky Way (talk) 14:54, 8 May 2017 (UTC)
 * And at least one ancient culture has been shown to have been aware of this correspondence – see Observations and explorations of Venus, Section 1.6 Maya. Is the 6-day week civilization in question the Akan? {The poster formerly known as 87.81.230.195} 2.122.60.183 (talk) 17:00, 8 May 2017 (UTC)
 * No, it is Eastern European. — 82.79.178.230 (talk) 22:21, 8 May 2017 (UTC)
 * The lunar month is somewhere around 28 days, depending on how you measure it (see article for details). That puts about 13 in a year. StuRat (talk) 15:43, 8 May 2017 (UTC)
 * See pages 28 and 29 of this book: .  There is a list of numbers in the left hand column (i.e. on the pages for March and April - the note at the bottom of March (continued at the bottom of April) tells you what they are).   Eight of these numbers generally appear in any thirteen - day period - moreover any number is 8 larger than the one above it (the numbers are not allowed to exceed 19 so you may have to add 19 to the second number to appreciate this). 195.147.104.148 (talk) 21:15, 9 May 2017 (UTC)

Whom to trust?
I've read two books (In French, by French people, printed in France), each one discusses a topic from a scientific point of view. The first one (talks about "Sleep") was against the use of alcoholic drinks and tobacco since they are harmful. The other one (about "Pleasure") encourages readers to drink and smoke and stuff, claiming that they are good for the human health! My question is: whom should we believe if both claim to be based on scientific evidence? (I don't mean only these books, but in general.) — Preceding unsigned comment added by 105.110.188.195 (talk) 09:33, 8 May 2017 (UTC)


 * Never trust anything that speaks in very general terms about "health". Health is far too complex a topic for any one factor to be "good" or "bad".  Instead, look to things which have specific outcomes (be they good or bad, which is up to you).  For example, Wikipedia has an article titled Alcohol and health which discusses specific outcomes of consumption of alcohol, including health risks (such as alcohol poisoning and alcoholic liver disease).  Then you have things noted at health effects of wine, which notes some potential health benefits from small amounts of drinking wine (an alcoholic beverage), including the French paradox, whereby some types of alcoholic drinks (including red wine) may be linked to better health outcomes.  It's FAR too simplistic to say that "alcohol is good for health" or "alcohol is bad for health" in such broad terms.  -- Jayron 32 10:24, 8 May 2017 (UTC)


 * If you find a source claiming that smoking is good for you, you can assume it was written by someone in the tobacco industry. ←Baseball Bugs What's up, Doc? carrots→ 11:20, 8 May 2017 (UTC)


 * I can think of a lot of drugs that are more pleasurable and less dangerous than tobacco! One of them is even legal in a few states... Wnt (talk) 13:01, 8 May 2017 (UTC)


 * This medscape article says: "any amount of alcohol increases the risk of getting a range of cancers." This is very true. Alcohol is poison. The title of the paper: "New UK Guideline" --AboutFace 22 (talk) 14:35, 8 May 2017 (UTC)


 * And there are documented health benefits of moderate alcohol consumption: . Certain negative health outcomes show small decreases in prevalence among people who consume small amounts of alcoholic beverages.  That is different than saying that alcohol is "healthy" which is far too broad of a statement to make.  There are risks, there are benefits, and it is up to the individual to make decisions after weighing them all.  Also "Alcohol is a poison" is only true in the sense of the dose makes the poison.  Water is also a poison (see water intoxication), and yet water is also OK in low enough amounts (vital even!).  -- Jayron 32 14:44, 8 May 2017 (UTC)


 * Also, in any such Q, we need to discuss the "versus what" part. For example, if their argument in favor of smoking is that it reduces psychological stress, then we should point out that there are many other stress reduction methods which don't involve inhaling toxins.  Try meditation, for example.  If their argument is that smoking keeps weight down, well then there are healthier ways to do that, like improved diet and exercise. StuRat (talk) 15:38, 8 May 2017 (UTC)


 * Closing, we can't comment on unspecified material. μηδείς (talk) 01:24, 10 May 2017 (UTC)

Magnetism
Since magnetism is electromagnetism, what is the wavelength and frequency of the photons around e.g. two bar magnets next to each other? Th4n3r (talk) 12:24, 8 May 2017 (UTC)


 * I'm not familiar with the most advanced theories of sub-atomic physics, which have all kinds of strange particles not usually mentioned in introductory university physics courses (with a target audience of science and engineering students). If we confine ourselves to electromagnetism as explained by Maxwell's equations, just because there are electric and magnetic fields, there isn't any electromagnetic radiation unless the electric and magnetic fields are changing. So in the situation you describe, supposing the bar magnets are static, there aren't any photons. Jc3s5h (talk) 12:42, 8 May 2017 (UTC)


 * This is a field of physics known as Quantum electrodynamics (QED). The math involved here is way over my head, but your question can be answered by QED.  -- Jayron 32 14:39, 8 May 2017 (UTC)


 * Without going into very difficult mathematics, we can give you this answer: the magnetic field around a bar magnet is, essentially, static - it does not change with time. So it is in steady state, which corresponds to zero frequency; hence, infinite wavelength.  This is why the photon model is not very useful when we describe steady-state ferromagnetism: if you want to describe a static magnetic field and you choose to write it down with the math that describes photons, you have to deal with a lot of zeros and infinities in inconvenient places.
 * It might frustrate you to see a real scientist talk to you about photons with wavelength-infinity. But, in photon physics, there are a lot of non-intuitive things you'll have to wrap your mind around.  Here is a brief anecdote that may help you to accept that this answer is actually correct and valid: in answering this question, I pulled out my copy of Griffiths' Electrodynamics....  After spending 500 pages building up the details of mathematical treatments for electromagnetism, the author introduces the photon in the very last chapter, by presenting a conundrum about conservation of momentum; and, in answering, he writes: "personally, I would regard this argument as a joke, were it not for the fact that at least one massless particle is known to exist in nature: the photon."
 * So - don't get too hung up on the conundrum: you can have wavelength-infinity waves, and you can even think of them as particles: they're just not behaving in a very particle-like way. They are not moving, they are not conveying energy and momentum.  If you write the math very carefully, these conclusions follow directly.
 * Nimur (talk) 14:54, 8 May 2017 (UTC)

Making sense out of North Korea's assassination plot suggestion
I don't doubt the North Koreans make stuff up or that they're nuts... nonetheless, killing Kim Jung Il sounds like a capital idea to most Americans. And I generally go by the rule of thumb that almost every nasty thing either side says about the other in any war is true, and this is a nasty thing. So can we make sense out of it? Now obviously it would help if someone can track down the original Korean and translate this without the "crazy" filter setting (I mean, I suspect it's pretty nuts in that language but I bet the BBC translators were hamming it up) but here is what I have to work with now:

A hideous terrorists' group, which the CIA and the IS infiltrated into the DPRK on the basis of covert and meticulous preparations to commit state-sponsored terrorism against the supreme leadership of the DPRK by use of bio-chemical substance, has been recently detected...

They hatched a plot of letting human scum Kim commit bomb terrorism targeting the supreme leadership during events at the Kumsusan Palace of the Sun and at military parade and public procession after his return home.

They told him that assassination by use of biochemical substances including radioactive substance and nano poisonous substance is the best method that does not require access to the target, their lethal results will appear after six or twelve months, bio-chemical substance can be added in cooperation with the CIA if one single correct information is obtained, the component of terrorism-purposed bio-chemical substance is the know-how of the CIA and it is only the CIA that can produce such substance, and that hardware, supplies and funds needed for committing terrorism against the supreme leadership will completely be borne by the IS. Then they handed him over 20 000 U.S. dollars on two occasions and a satellite transmitter-receiver and let him get versed in it...

In January, May, August and September of 2016 IS agents had satellite contacts with Kim who resided in Pyongyang. The IS agents gave instructions to choose and report the most effective and safe method with high probability of success while presenting him various terrorist methods using biochemical substances along with operational code of terrorism against the supreme leadership, the ways of bribing an object who would directly carry out the terrorist act and ways of entering the grounds of events.

On August 12, 2016 they gave him an instruction to collect and send as much information as possible concerning the surrounding environment of event ground where celebrations are held frequently, guard situation there and orders observed at times of events, saying that once concrete and detailed data are given, they would study the most reasonable way in cooperation with the CIA...

In March and April last an IS agent [name omitted] and his secret agent [name omitted], met the terrorist accomplice in Dandong of China and handed him over new satellite transmitter-receiver and 50 000 U.S. dollars. They signed a "contract" on setting up the overseas liaison center and let the necessary equipment and materials be introduced as the first instalment in early May.

On April 7 a guy surnamed [name omitted], chief of the IS team, taught Kim the way of bribing terrorist accomplices, saying that "even the U.S. CIA uses gradual engagement with due consideration given to the greed and mentality of persons depending on which class and strata they belong" and told him to use it as a reference in engaging terrorist accomplices to be infiltrated to the event ground.

On Nov. 4, 2016 and on April 13, 17 and 20 this year they let Kim know that they officially confirmed the types of bio-chemical substance and hardware to be used for committing terrorist act against the supreme leadership and requested it to the CIA, and instructed him to restudy the "creed" of the terrorist executor and reconfirm the state of "brainwashing" of him and report about them. They also repeatedly instructed him to take the best measure for the examination and preparations for the terrorist operation, as there can be such catastrophic incident as a war once the fact about terrorist means and funds provided by the IS is known.

The chief of the south Korean puppet Intelligence Service [name omitted] praised the terrorist as a "very valuable existence for the nation and 'IS'" and directly organized the terrorist operation and let the chief of the IS team [name omitted] and agent [name omitted] take the lead in executing it. The puppet forces gave the terrorist more than 80 instructions for the execution of the operation.

The remarkable claim here is that it is a radioactive substance and a biochemical substance. This implies a level of sophistication in the attack comparable to something like a targeted cancer therapy that brings a radioactive isotope to a specific (cancer) cell to kill it. The North Koreans have obviously thought up the notion of finding some cell type to target (what???) that is a lot less dispensable than a cancer cell. Whether they have thought that up by interrogating a U.S. agent or have purely invented it in their own laboratories to use on us, it is still of interest.

Anyway, some topic of interest here: is there any record of people considering "targeted assassination therapy", and what would they target? Is there something that is easier to inhale and get into a bloodstream than an antibody that they could link to the radioactive isotope? Or would they just be hoping to make a lot of shrapnel and something would hit, or do they have a way to make inhaled antibody cross from lung to bloodstream? There are so many options here I don't even know where to begin - that's obviously a really vague source text. What can we think of? Wnt (talk) 14:05, 8 May 2017 (UTC)


 * Oh, my --- I just looked up Kim Hak-Song on PubMed and found several results, including this cancer therapy targeting paper. (other results - I have no idea whether that is the same person - the address for author information was in South Korea (and also is in the latest publication even though NCBI somehow left it out, sorry)  If the North Koreans are writing a novel here, they certainly did their background research.  Wnt (talk) 14:40, 8 May 2017 (UTC)


 * Possible relevance: "repebody" molecules that are bacterially produced antibodies with multiple leucine-rich repeat modules -- earlier paper by Kim.  IF the North Koreans can be taken at their word, one of these might currently be under selection by someone working with the CIA to recognize a target on critical cells.  (It is quite possible that the researcher involved is unaware he is helping to build a weapon).  This patent covers repebody inhalation, but it might be purely boilerplate.  Ditto this one, which also talks about inhaled aerosols.  Actually, it looks like the repebody term is almost unique to this researcher, and is based on an understanding of the lamprey immune system - it can benefit, however, from rational design using LRRs from known human proteins.  It's introduced here - when I get time I'll try to understand how it actually works.  This seems like an interesting, multi-purpose technology. Wnt (talk) 15:03, 8 May 2017 (UTC)


 * Going back the the OP's question. Doubt if there is any plot to assassinate Kim Jung. It would not achieve anything, because in this type of regimen there is always someone else that can step in. So, there is no chance of creating a 'power vacuum' which could destabilize the regimen.  Things would  just carry on as normal. Secondly, the DPRK are not nuts. The 'family' are brought up learning gamesmanship. They are very astute and very ruthless towards anyone who descents. Third: biochemical substances and nano poisonous substance may be metaphors. Most NK's are peasants. The  DPRK is able to maintain control with the help of  small middle-class elite.  Being well educated they are naturaly very curious about the outside World to which they have no Internet nor any other access. Therefore: Nano poisonous substances  may refer to some plans which include simple things like launching balloon from South Korea to drop pen-dives and DVD's  on the middle-class city in NK just across the river. The data in them could even included copies of WP.  The NK finder may well feel too frighted to tell their friends at first  -as to  what the have discovery and read – but then one must take into account  human nature. If the drops of data are intensive enough, some will realize from normal conversational topics,  that their friends have also  read these drops, and a bond of mutual understanding and trust forms as they discus what they have learnt. A similar thing is thought to have helped to destabilize the former Soviet Union. The privileged elite, could get not only Betamax video machines but films. Glimpsing the outside World  made them discontented with the then Soviet  regimen.  Result was that the  regimen lost the 'blind' support of the elite and the rest is now history.  Kim Jung was born in Russia and he may be using the metaphor biochemical substances to refer to the elite of the former Soviet Union which turned on their suppressors once they eyes had been opened. Unfortunate, the military elite of all or most counties like a blitzkrieg. They just want to storm in, leaving long term problems in their wake,  rather than taking the gently, gently approach.   Those that forget history are doomed to relive it. This is not an issue to be left up to the politicians in the 21st Century – it can lead to an ever  more dangerous situations,  which as ever, the politicians & military  will make a mess of – if  left to them. We (the World) need to become (or already are) the biochemical substances to bomb any repressive regimen  with Nano liberating substances. Aspro (talk) 00:12, 9 May 2017 (UTC)

Does the Milky Way rotate around anything?
For a haywire SF plot, I'm stepping through rotational frames of reference and summing up angular velocities relative to a given gravitational center (Earth rotation, Earth orbit, orbit of solar system around galaxy center...). Now I'm trying to figure out whether I can go one farther and add an angular velocity for the movement of the Milky Way. However, IIUC, there is no indication of actual rotation of the Milky Way around, e.g., the gravitational center of the Local Group, or anything at larger scales. Once we leave the galaxy, movements are linear and/or omnidirectional (Hubble flow, microwave background). Is that correct? -- Elmidae (talk · contribs) 15:17, 8 May 2017 (UTC)


 * See: Supermassive black hole — 107.15.152.93 (talk) 15:25, 8 May 2017 (UTC)


 * That contributes to rotation within the galaxy, while the OP was asking about rotation of galaxies relative to each other. StuRat (talk) 15:28, 8 May 2017 (UTC)


 * Note also rotation vs. revolution; this is actually about the latter. Wnt (talk) 01:08, 9 May 2017 (UTC)


 * I always learned that the movements on those scales - larger than the local group - were virial (thermal). Nowadays, every cosmologist you talk to has a different idea - there is less consensus than there was many years ago.  I would attribute that development to the rise of powerful computers that can simulate general relativity - so lots of people can try out various theories and make predictions that are consistent with observational data.  Nimur (talk) 15:26, 8 May 2017 (UTC)


 * That some galaxies move towards each other and eventually collide, rather than moving away, to me suggests there are eddies in the large-scale movements of galaxies. This also implies rotation within those currents.  However, at human timescales, I'm not sure if those can be measured.  That is, the time for a significant change in direction to occur may be longer than we have been measuring.   StuRat (talk) 15:27, 8 May 2017 (UTC)

See the Local Group and the Great Attractor. Most bodies in motion towards each other tend to be off center and hence have some rotational component (think of the Theia hypothesis but the space scale may be so vast we have not had time to observe it directly. μηδείς (talk) 17:22, 8 May 2017 (UTC)


 * [Edit Conflict] "Eddies" and "currents" are deceptive terms in this context, as galaxies are not (so far as we know) embedded within any fluid that could apply external positive pressures to them – force fields such as gravity are not fluids and do not have eddies and currents in this sense (despite Eddy currents!).
 * It is however fairly trivial that in a gravitationally bound group of galaxies such as the Local Group, all members must be orbiting the group's common barycentre, just as is the case with larger Galaxy clusters, and heirarchically upwards with Superclusters. (One also needs to take account of the dark matter associated with the galaxies individually and perhaps the Group as a whole.) However, orbits are not just circular, they are elliptical and can be of any eccentricity, even approaching linearity. Moreover, on the huge duration scales involved in movements of galaxies, it would be very difficult for us to observe any curvature of their orbits directly – we can only take effectively instantaneous measurements of their velocities, which will appear linear until we take more measurements over many millions of years.
 * The Milky Way and the Andromeda Galaxy are currently nearing each other and are clearly gravitationally bound; all other members of the Local Group are by comparison much less massive, and most if not all of them will likely also be bound (though interactions could conceivably cause some satellite galaxies, globular clusters or individual stars to exceed escape velocity). {The poster formerly known as 87.81.230.195} 2.122.60.183 (talk) 17:45, 8 May 2017 (UTC)


 * Re: "galaxies are not (so far as we know) embedded within any fluid that could apply external positive pressures to them". See dark fluid for one possible theory that proposes just that. StuRat (talk) 22:02, 8 May 2017 (UTC)


 * If by "one possible theory" you mean "one dude with a crazy idea" (he's basically the only sources for that poorly cited article). -- Jayron 32 00:45, 9 May 2017 (UTC)


 * I found a 1999 article about the Sun's motion relative to the Local Group here. It says the Sun is moving at 300 km/s "relative to all LG members" and gives a heading in Galactic coordinates that I should admit I don't necessarily understand.  There is discussion about a local standard of rest that refers to the barycenter of the Local Group and/or the point where cosmic background radiation is equally shifted from all directions, but I didn't follow what they did there.  I assume someone reasonably skilled in the art is supposed to know the Sun's motion relative to the Milky Way and can mentally delete that from its Local Group motion...  in any case, there must be updated numbers if you search for what cites that.  But the bottom line is that the Local Group is defined by mutual gravitation and is relevant.  As opposed to the situation with Great Attractor, where they start talking about "peculiar motions" because everything is being pulled apart by expanding space!  There really is a scale beyond which there are no orbits; it's just bigger than the Local Group. Wnt (talk) 01:30, 9 May 2017 (UTC)


 * @Wnt: l is galactic longitude. b is galactic latitude. Those coordinates are about in Cepheus or so towards the plane of the Milky Way. a is altitude and A is azimuth. Alpha is right ascension because they ran out of English A's and delta is declination. Lambda is ecliptic longitude and beta is ecliptic latitude because they both can't be lambda and alpha's already taken. Ecliptic longitude is more important so it gets to be lambda. Galactic coordinates use the English versions of the ecliptic Greek letters and supergalactic latitude and longitude are just SGB and SGL because they're new and they've run out of good options. Their use of apex is likely analogous to the "apex of the Sun's way" which is it's motion relative to the galaxy. If you're wondering if there's a left ascension or wrong ascension then no. The opposite of right ascension is oblique ascension which is what's ascending (rising) at any given time from where the equator is at oblique angle to the horizon instead of a right angle (that is, not the terrestrial equator (or poles where horizon and equator are parallel)). It is much more obscure than right ascension. Sagittarian Milky Way (talk) 02:37, 11 May 2017 (UTC)

Alright, thanks guys. This strikes me as "it's complicated, but for practical purposes there is no orbiting motion with readily discernable characteristics". That should be enough to not make me break my intended Level 4 position on the SF Mohs Scale :) -- Elmidae (talk · contribs) 08:01, 9 May 2017 (UTC)

That wasn't the message I meant to send with my comment about the paper above. It actually did define a region based on the distance where the gravity from the Local Group can retain galaxies within a region ... I think. So AFAICT the Milky Way is orbiting ... it's just that the nature of the "center" in a group of galaxies, when there are a few stray galaxies mixed in that aren't expected to be gravitationally bound but nonetheless affect the whole, and all the data is incomplete anyway, is a little iffy. Wnt (talk) 16:15, 9 May 2017 (UTC)


 * Appreciate it! And if I was writing an article or a paper, I'd have to dive into that. But really, fact-checking for an SF story is equal parts mining for ideas and ass-covering. As long as I'm not committing a blatant faux-pas here ("Everyone knows that the Milky Way orbits the Manichaean Gap!") and not overlooking some obvious cool feature to exploit, I'm good. - Leaning far enough out of the window in some other aspects, admittedly %) -- Elmidae (talk · contribs) 17:05, 9 May 2017 (UTC)

Blackest black fabric that is reasonable to achieve?
I want a black backdrop for making some project videos for YouTube and photographers seem to recommend velvet but it seems to me that even velvet can have some sheen and reflect light, appearing grey. Would it make sense to buy a fabric and then attempt to dye it further? It's possible that all the locations in the fibres that can be occupied by the dye are already occupied. I know photographers can make a white background look black in a suitable environment but that's not possible in the confinement of my living room. How to make a surface not reflect visible light and absorb more? --78.148.99.149 (talk) 16:26, 8 May 2017 (UTC)
 * Maybe get ahold of some super black? Or maybe use a more solid background, such as a piece of plywood painted in matte or flat black?  Just some ideas.  -- Jayron 32 16:42, 8 May 2017 (UTC)
 * Velvet is the right idea, but most velvets are designed to shine, so they're made from a fabric with fibres that are individually shiny. It doesn't usually look grey, more of a pearlescent sheen mixing black and quite light shades. A cotton velvet might do it, or even a moleskin. With a budget, you can simply buy backcloth fabrics that are made to be an invisible black. In the fabric shop though, you're probably looking at dull non-sheen cottons, rather than velvets. Once you're far enough away to not see the weave, it matters less what the fabric is. Andy Dingley (talk) 17:05, 8 May 2017 (UTC)
 * Velvet also shines more when seen at an angle. You can get a small piece and experiment before you buy enough for an entire set. μηδείς (talk) 17:16, 8 May 2017 (UTC)
 * Some photographers use the lining from blackout curtains. This may require 2 layers if the weave is more open than you wanted. DrChrissy (talk) 17:49, 8 May 2017 (UTC)
 * The lining of my blackout curtains seems to be a shiny silver color. It is opaque but not at all nonreflective.  CodeTalker (talk) 21:50, 8 May 2017 (UTC)
 * When I've done black backdrops for photographs (IANAPP so take this advice with what it is worth), I've just used off-the-shelf black linen sheets from a big box store, something like thus. No idea if that serves your purposes or not.  You may want to actually go to the store to look at it rather than order online to see if it meets your needs.  -- Jayron 32 17:52, 8 May 2017 (UTC)


 * Want the ultimate non-reflective coating (price is no object)? See: Vantablack &  — Preceding unsigned comment added by 107.15.152.93 (talk) 21:12, 8 May 2017 (UTC)
 * The professionals simply use a green or blue screen aka "colour-separation overlay" for such purposes. --Kharon (talk) 02:37, 9 May 2017 (UTC)
 * The OP does not explain the purpose of the black backdrop. An analog video signal can never represent absolute black, it has only a systematic "black level" that is limited by Signal-to-noise ratio and Lens flare. Chroma key as Kharon says is an effective way to replace a background with any desired color (or a background image) but depends on having en evenly lit rear wall in a uniform color that does not occur in the main subject. A Test card of physical, not digitally generated type, for TV cameras was made by Marconi to calibrate a wide range of brightness; the black segment of the grey scale was actually a porthole to a black velvet lined box constructed behind the card. Blooteuth (talk) 11:34, 9 May 2017 (UTC)

Personality types.
This article explores an interesting concept that people can broadly be put into 4 different categories. However, can it be argued that this is too broad even for managing relationships in the workplace? Because this could differ based on different cultures (whether organisational, related to a specific profession) or even depending on a person's mood or period of their life. In addition, I can think of many personality types which don't fit into these 4 categories. For example, where would you put the competitive type who likes to play strategic mind games with others, often prevalent in macho organisations? 2A02:C7D:B953:4700:4F9:B85D:C8AB:CF4F (talk) 17:31, 8 May 2017 (UTC)
 * Wikipedia has an article on Personality. Perhaps you would like to look a that first and then come back with a more specific query. Dmcq (talk) 17:36, 8 May 2017 (UTC)
 * Alfred Adler would have strongly disagree with such rough categories while Sigmund Freud always seemed to like (intellectually) sorting individuals into just a few big boxes. The resulting two main- and some other, newer, different "schools of Psychology" are the base for Science till today. So if you would ask your question at two different (real) Experts you likely would end up with 3 opinions nevertheless. --Kharon (talk) 02:26, 9 May 2017 (UTC)
 * Jung said 16 types. Five factor model would say 32 black or white types and more gray types. Sagittarian Milky Way (talk) 02:57, 9 May 2017 (UTC)

US energy efficiency drop
In both 2011 and 2016, US used approximately 97 quads of primary energy. In 2011, 41.7 quads went into energy services, a 43% efficiency. While in 2016 only 30.8 quads went into energy services, resulting in an efficiency of only 32%.

With all the talk about electric cars and energy conservation, I expected a slight improvement in overall energy efficiency. But this is a eleven percentage points drop in energy efficiency. In just five years! What's going on here? ECS LIVA Z (talk) 18:37, 8 May 2017 (UTC)


 * The change to energy-efficient light bulbs in homes may be a big factor, if not the biggest. ref - Akld guy (talk) 20:07, 8 May 2017 (UTC)
 * So energy efficiency should be going up then, right? I'm asking why instead it's dropping like a rock. ECS LIVA Z (talk) 20:11, 8 May 2017 (UTC)


 * I don't know the answer, but I notice that the biggest difference between those two charts seems to be the efficiency of the "industrial" block.
 * Perhaps something changed there. (Obvious question : Is this a real effect, or a change in how those numbers are reported?)ApLundell (talk) 21:37, 8 May 2017 (UTC)


 * You do realize that electric cars are highly inefficient. The batteries are hugely expensive, the charging networks the same, and the electricity still comes from burning hydrocarbons.  This is simply hid from the end-use consumer, since he doesn't see the huge subsidies the car makers get and the coal plants and transmission wires losing energy to heat as they carry the wattage of huge distances.  But think of how efficient they are at virtue signalling!


 * The description under the charts points out that these numbers are estimated. Also such "global" numbers actually reflect the efficiency of the energy market, not of the technology used. However energy services are generally becoming less efficient (economically!) because a service network always needed to be balanced, or more specifically power supply always needs to be regulated according the power demand, and since the socalled renewable energy production produces energy independent of demand and unpredictable, yet has (politically given) priority to be used, the conventional electric power production is shut off more frequent the more renewable energy takes its increasing share of the total. This is one possible but not necessary the main reason for these numbers. Another could simply be that, besides renewable, the main production switches to whatever natural resource is the cheapest. Given the changes on the market for crude oil, gas and coal this can change these numbers too. And last not least allot of energy is "wasted" because it needs to be transfered. Even the advanced 800 kilovolt High-voltage direct current lines have a loss rate of 4%/1000km. Ofcourse local low voltage nets have a much higher loss rate and on top this all adds up in total. --Kharon (talk) 01:44, 9 May 2017 (UTC)


 * Fixed your link. --76.71.6.254 (talk) 05:30, 9 May 2017 (UTC)
 * Looking at the flowcharts, it's clear that electricity wastage is less of a factor - the rejected energy directly from electricity generation goes down, and the rise in rejected energy from industry is greater than the input to industry from the electricity generation. So a large chunk of the efficiency drop off is probably due to the direct industrial uses of natural gas and petroleum. For residential use, the change in efficiency might be related to electricity wastage, but that's a smaller contribution to the total waste.
 * Reading the notes gives a better picture - the 2016 flowchart is calculated assuming 65% energy efficiency for residential and commercial, and 40% for industrial (based on the DOE's estimate of manufacturing in 2017). For 2011, those three sectors are calculated assuming 80% efficiency.  So the efficiency on the chart has gone down because the estimated efficiencies used to calculate it have been changed - and to see the reasons for that, you'd need to find which DOE report the revised estimates are based on. MChesterMC (talk) 09:38, 9 May 2017 (UTC)


 * As MChesterMC says, it's really a bookkeeping issue. The primary inputs to the users are easily measured while the user efficiency is estimated, not measured. For sure, LEDs use roughly 1/10 the power of incandescents for the same amount of light, but was electricity wasted by incandescent bulbs counted as "rejected" or not? -Arch dude (talk) 19:45, 9 May 2017 (UTC)


 * Agree with MChester - note that it says the estimates were "updated" in 2017, and the 2016 estimates were all 4/5 or 1/4, which means they were probably really handwavey numbers. So I'm not sure anything actually changed at all, and if it did, it probably changed over much more than one year, and if it did, it might be something like that light bulb case mentioned. Wnt (talk) 01:07, 10 May 2017 (UTC)


 * Do we use electricity to produce gasoline from CO2 or hydrocarbons to produce electricity? μηδείς (talk) 01:18, 10 May 2017 (UTC)
 * Not yet, but science or to be more precise Industry is very, very interested in developing such processes because then they could keep using cheap (or to be more precise almost "free"(when they already payed for the licence to exploit an available source)) fossil fuels without the increasingly threatening perspective of paying more and more carbon taxes or for carbon pollution certificates. --Kharon (talk) 01:54, 10 May 2017 (UTC)


 * 1) We use hydrocarbons (methane, i.e., natural gas) and just carbon (coal) to produce electricity. These charts show that we are shifting from coal to methane, which produces less CO2 for the same amount of electricity. All the other electricity numbers change only a little.
 * 2) There is no economic incentive to produce liquid fuel from electricity in general. There is one major exception. The US Navy would really like to produce jet fuel and ship fuel from electricity and/or steam generated by the nuclear reactors aboard aircraft carriers. The carrier's time on station is limited primarily by the fuel needed by its aircraft and escorts, so they are actively researching this. -Arch dude (talk) 22:48, 10 May 2017 (UTC)

Animals swallowing live prey
I saw a video of an African Bullfrog swallowing a mouse whole without chewing or anything. The mouse was still alive without even a scratch as it was swallowed. How come the mouse can't attack the insides of the Bullfrog and escape? Isn't swallowing live prey that can attack your insides very dangerous? How long would the mouse be alive down there and what would be the cause of its death?--83.136.45.50 (talk) 21:50, 8 May 2017 (UTC)


 * I once drowned a mouse, and it took 12 seconds for it to stop moving. (I wasn't trying to be cruel, but it was caught in a glue trap and this seemed to be the quickest way to stop it's pain.)  But I've wondered myself why animals which are prey to such animals that swallow them whole don't evolve a defense against being swallowed whole, like porcupine spikes, pointed in all directions. StuRat (talk) 22:19, 8 May 2017 (UTC)


 * Put the mouse in a plastic bad and step on its head. Death in under a second, and then discard the bag.  Drowning is much crueler, μηδείς (talk) 23:04, 8 May 2017 (UTC)


 * I was right by the sink, and it would have taken longer to get a plastic bag. StuRat (talk) 23:31, 8 May 2017 (UTC)


 * In small apartments in NY it's common practice to hang the day's small plastic shopping bag from the doorknob for use as a teporary trash depositso it can be taken out to the building's garbage when next you leave. In any case, I would discount the stuck time from the equation as irrelevant, and prefer One hour and 12 seconds of being glued, then an instant, imperceptible death, to an hour of being glued then 12 seconds of being drownt. μηδείς (talk) 01:14, 9 May 2017 (UTC)


 * And here I thought a trash bag on the doorknob meant "Don't come in, I have a trashy woman in here". StuRat (talk) 16:53, 9 May 2017 (UTC)

Animals do develop defences against being swallowed whole. There are species of catfish that have sharp spines that evolved to get stuck in the predator's throat (I'll find a link in a minute, I forgot the binomial for it but it'll come back to me soon enough). There are rough-skinned newt species that have TTX toxin in their skin secretions: they've been documented to kill a toad and climb back out from toad's mouth intact. Finally, there was a paper recently about a typhlops surviving a trip through a toad and coming out alive from the other end (with pictures - NSFW). Dr Dima (talk) 22:51, 8 May 2017 (UTC)
 * Here: "‘Fantastic Voyage’: a live blindsnake ... journeys through the gastrointestinal system of a toad" Dr Dima (talk) 22:55, 8 May 2017 (UTC)
 * Oh, and also check out porcupinefish, of course. Dr Dima (talk) 23:04, 8 May 2017 (UTC)


 * The mouse is effectively crushed, stopping its lungs and perhaps its heart, while the other prey are smaller and cold blooded. This goes along with  recent research that says constrictors kill by stopping the heart, not suffocation.  Notice the bullfrog even closes its eyes to help force down the mouse. http://news.nationalgeographic.com/2015/07/150722-boa-constrictors-snakes-animals-science-kill/ μηδείς (talk) 23:02, 8 May 2017 (UTC)


 * Humans swallow live prey, sometimes without much chewing. See raw bar.  -- Jayron 32 00:42, 9 May 2017 (UTC)


 * That's where "live raw shellfish are shucked and served". The shucking part is what many animals which eat their prey live might have trouble with, lacking the tools for the job.  (Those which have the tools general tear their prey into bite-sized bits before swallowing.) StuRat (talk) 00:45, 9 May 2017 (UTC)
 * Animals have their means of shucking. Aeschylus is insightful.  Also, krill are eaten live by baleen whales.  No shucking involved, just scoop them up by the thousands.  -- Jayron <b style="color:#090">32</b> 00:49, 9 May 2017 (UTC)
 * See Jonah and . 195.147.104.148 (talk) 20:45, 9 May 2017 (UTC)