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October 26

Lead leaching out of metal

We sometimes fry things on a big slab of what seems to be carbon steel. Someone gave it to us from some plate steel place where they make stuff out of it, but not cookware. There are giant, thick sheets laying all over the place. It looks like steel or carbon steel or something. It rusts quickly but is nicely seasoned now and so is very non-stick. Do you think it's loaded with lead? Would lead leech out into the oil. Is there a way to test this? Anna Frodesiak (talk) 05:48, 26 October 2017 (UTC)

Your piece of steel plate is highly, highly unlikely to contain any lead. The only steel to contain lead is free-machining steel. This is a very specialised application for steel and there is no reason for free-machining steel to be rolled into flat plate. Alloying elements in steel, such as carbon and manganese, are tightly bound within the atomic lattice and they do not leach out of the steel. Dolphin (t) 06:28, 26 October 2017 (UTC)

Thank you very much, Dolphin51. :) Anna Frodesiak (talk) 08:43, 26 October 2017 (UTC)

Also, with a properly seasoned iron surface, the food never touches the actual metal. --Guy Macon (talk) 15:57, 26 October 2017 (UTC)

Yes, but that doesn't mean the two don't chemically interact. Iron can dissolve in the oil, and some of that gets in the food. This is actually considered a benefit of a cast iron pan, that they increase the iron content in your food. StuRat (talk) 16:33, 26 October 2017 (UTC)

Note carbon steel is the (current) most common material for making woks, Wok#Carbon_steel. May have been part of why the locals knew it was good for cooking. SemanticMantis (talk) 21:39, 26 October 2017 (UTC)

Thank you, all. Your helpful information led me to create Media related to Carbon steel at Wikimedia Commons and populate it and add the commonscat to the main article.

Now, I see Media related to Crystal structures of steel at Wikimedia Commons and wonder if any or all of those should have the carbon steel parent category added. Thoughts?

Oh, and they want to get rid of the refdesk because it doesn't help other parts of the project. Phooey to that. You folks are wonderful and so helpful. Anna Frodesiak (talk) 01:31, 27 October 2017 (UTC)

The articles listed under “Crystal structures of steel” are all eligible to be included under “Carbon steel”. Incidentally, I notice the heading “Perlite (Steel)”. This spelling is definitely incorrect because perlite is something of interest in geology. In the context of carbon steel the spelling should be “pearlite” and is so named because of its resemblance to mother-of-pearl when viewed under a microscope. Can you tweak the spelling? Dolphin (t) 07:10, 27 October 2017 (UTC)

Hi Dolphin51. Thank you! I've made the new cat, added the items to it, and speedy tagged the old one. I also fixed the article's commonscat.

Now, should I simply add carbon steel as a parent cat to Crystal structures of steel, or individually add carbon steel parent cat to Austenite, Bainite, Cementite, Ferrite (Steel), Ledeburite, Martensite, Pearlite‎? Best, Anna Frodesiak (talk) 00:33, 28 October 2017 (UTC)

I think it will be sufficient to add Carbon steel as a parent cat to Crystal structures. Dolphin (t) 11:11, 28 October 2017 (UTC)

Done! Thank you, my friend! Anna Frodesiak (talk) 13:30, 28 October 2017 (UTC)

Small linguistic remark: You mean leaching. "Leech" with the double-e is another thing entirely. --Trovatore (talk) 08:29, 27 October 2017 (UTC)

Ah, leaching, yes, of course. Thank you Trovatore. :) Anna Frodesiak (talk) 00:33, 28 October 2017 (UTC)

Mass to the Moon

I understand the moon is moving away from the earth by 4 centimetres every year, how much mass would have to be added or lost for it to stay in perfect orbit? JoshMuirWikipedia (talk) 12:59, 26 October 2017 (UTC)

Well, momentum is potentially unlimited, so if a well-placed alien has a sufficiently decent particle accelerator, and we wrap the Moon carefully in some sci-fi quality electrical tape to keep it from exploding, we ought to be able to knock it back where you want it with just a few protons. Of course, with current technology ... any method is impossible.

Also note this doesn't change the tidal acceleration; it would only be modifying the present orbit. The same should be true of any one-time mass impact. Wnt (talk) 13:31, 26 October 2017 (UTC)

• Changing the mass wouldn't have any effect.

Sadly WP doesn't have a clear introductory article to this. Circular orbit is about the closest. Also Kepler's third law "The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit." was determined by observation, before Newton had worked out the gravitational theory behind it.

For a simplified circular orbit, the period of that orbit

$T=2\pi {\sqrt {\frac {a^{3}}{GM}}}$

where:

• $T$ is the orbital period
• $a$ is the orbit's semi-major axis in metres (altitude from the centre of the Earth, in our simplified view)
• $G$ is the gravitational constant,
• $M$ is the mass of the Earth

So the Moon is moving away because it's slowing down. To bring it back, you'd have to speed it up. Andy Dingley (talk) 13:43, 26 October 2017 (UTC)

And the moon is slowing down because of gravitational drag due to tidal effects. Basically, some energy in the moon's motion is lost because it goes into distorting the earth's shape a bit. That lost energy causes the moon to slow down ever so slightly which causes its orbit to drift outward ever so slightly. This will not last forever, because other factors will lead to the moon-earth system becoming tidally locked so that there is no more drag on the moon. --Jayron32 15:14, 26 October 2017 (UTC)

Wait, slowing down? No that's backwards. The moon is speeding up. (Higher orbits are faster orbits.)

It's speeding up because earth's spin (one rev/day. Fast) and the Moon's orbit (one orbit/month. Slow) are slowly converging. So the Earth is slowing its spin, while the Moon is speeding up its orbit.

ApLundell (talk) 15:56, 26 October 2017 (UTC)

Yes, of course. Damn sign conventions get me every time. My bad. --Jayron32 17:33, 26 October 2017 (UTC)

• I don’t think “higher orbits are faster orbits” is right. In the formula given above by Andy, the time period T is proportional to $2\pi a^{3/2}.$ Speed S = distance per unit time, so T = const × distance/ S where distance travelled is the circumference $2\pi a.$ Equating the two expressions for T gives $ka^{3/2}=a/S.$ So higher radius a is associated with lower speed S. Loraof (talk) 17:39, 26 October 2017 (UTC)

No, he's right. It's simple orbital dynamics. I've seen Buzz Aldrin (who did his PHD thesis on the matter) discussing it in layman's terms before; but the basic principle is faster = further out. When you are in orbit, and you increase your forward velocity, you move out in orbit. More kinetic energy = further from barycenter. This is true in any rotational system (that's why electrons with more energy are at further distances from the nucleus of an atom, for much the same reason) Thus if the moon is moving outwards, it must be doing so because it is moving faster. If you slow down, you move into lower and lower orbits; if you go too slow your orbit intersects the larger object and you crash into it. --Jayron32 17:45, 26 October 2017 (UTC)

You’re describing speed between orbits. For objects in orbit with no externally imposed acceleration (other than gravity maintaining a given orbit), my math looks correct to me. Examples of orbital speed around the Sun: Earth 29.78 km/s; Mars 24.07 km/s; Jupiter 13.07 km/s. I was objecting to the statement “higher orbits are faster orbits”. Since the Moon is continually changing orbit, so to speak, part of its speed is not speed of orbit. Loraof (talk) 18:05, 26 October 2017 (UTC)

You know what, forget me again. I really shouldn't get involved in these problems. I'm such an asshole. --Jayron32 18:17, 26 October 2017 (UTC)

No, you’re not – you’re far and away the most helpful person on these ref desks. And your last comment was valuable in clarifying the difference. Thanks for all your work here! Loraof (talk) 18:24, 26 October 2017 (UTC)

If you add mass to Earth instead of the Moon and do it gradually then it might work. PrimeHunter (talk) 15:47, 26 October 2017 (UTC)

The moon is actually gaining energy from the rotation of the earth via the leverage of the tidal bulges (the earth's rotation drags these around so that they are ahead of the moon). Perversely (but in accordance with the virial theorem), for every one unit of energy transferred from the earth to the moon, the moon spends two units of energy in climbing higher: the one it got from the earth plus one from its own store of kinetic energy - so it ends up going slower. --catslash (talk) 16:47, 26 October 2017 (UTC)

• As is always the case with questions like "what would happen to [gravitational phenomenon] if we added mass to [celestial body]", the answer is: it depends on how the mass is added. The above answer (in particular AD's) give the answer with the assumption that mass is instantaneously added with no change in any of the velocities at that instant. Tigraan^{Click here to contact me} 18:43, 26 October 2017 (UTC)

Given

Moon's radius 1757.1 km

Moon's mass 7.342E22 kg

the Moon's center of gravity can be moved about 4 cm closer to Earth by adding a mass (7.342E22 x 0.04)/1732.1E3 = 1.70E15 kg on the side facing Earth, taking care to match velocities before contact. Continual deliveries of 2E11 kg every hour (the US annual waste production) might be a nice way to keep the Moon's orbit constant. Blooteuth (talk) 19:12, 26 October 2017 (UTC)

People think the moon is speeding up because the lunar month is getting shorter. What is actually happening is that the moon is slowing down but our clocks are also slowing down because of the tidal drag (as measured by successive transits of the meridian by the sun, mean solar time). The clocks are slowing faster than the moon, so it appears to be going faster. 92.8.218.38 (talk) 14:15, 27 October 2017 (UTC)

Kepler's third law requires that "the square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit." Hence we have ${\frac {T^{2}}{a^{3}}}={\frac {4\pi ^{2}}{G(M+m)}}\approx {\frac {4\pi ^{2}}{GM}}=\mathrm {constant}$ where M is the mass of the Sun, m is the mass of the planet, and G is the gravitational constant. When this law is applied to any two masses, the constant of proportionality has, in turn, a value that changes with the system's total mass M + m. Thus changing the Earth-moon system's total mass in any way has to change either the system's orbital period, the distance of their semi-major axis or both in order for Kepler's law to remain valid. With the problem at hand, if the angular momentum of the original Earth and moon masses are conserved then we also require that ${\frac {a^{2}}{T}}=k$ where k is a constant. In other words, as their orbit about their common barycenter becomes more distant their orbital period is longer (as noted by others above). Consequently, solving these two equations shows that increasing the system's total mass will arrest their separation and shorten the lunar months (such that Kepler's third law holds). It's not a difficult calculation, but I haven't a lot of patience to punch in the numbers to determine how much mass would need to be added from afar each year, but you can have a go with it by first calculating the conservation constant for the current Earth-moon system as it now stands and plugging away into the following: $\Delta M={\frac {(2\pi *k)^{2}}{G\left(a+\Delta a\right)}}-(M_{1}+M_{2})$ -Modocc (talk) 04:59, 28 October 2017 (UTC)

Hydraulic motors

Why are hydraulic motors not more popular for vehicles? Hydraulic pump and motor pairs seems to be a very efficient way to transmit motive force from an engine to wheels. It eliminates friction losses from multiple gears, shafts and other moving parts in conventional transmission systems, and also weighs much less. I get the idea I'm missing information about one or more major disadvantages that explain why it's so rare. Roger (Dodger67) (talk) 19:01, 26 October 2017 (UTC)

Hydraulic linkages are indeed efficient and are employed in automatic transmissions. But your vehicle will need a prime mover i.e. a motor that converts energy from a source energy into mechanical energy. What source energy would you like to pay for? Blooteuth (talk) 19:25, 26 October 2017 (UTC)

Blooteuth I'd imagine an internal combustion engine driving a hydraulic pump would be the most obvious prime mover. The hydraulic linkage within a conventional transmission just one small component, I'm wondering why hydraulics are/were not used far more to basically eliminate almost the entire mechanical gear-and-shaft based drivetrain between engine and wheels? In recent years of course eletric drive has become far more efficient with hybrid IC/battery or even pure battery driven vehicles becomming more common. Hydraulics just seems to have never been considered a viable replacement for the conventional drivetrain. Roger (Dodger67) (talk) 19:43, 26 October 2017 (UTC)

• Don't confuse hydrostatic transmission with hydrodynamic. Hydrostatic transmissions (pump and motor) are limited in power, speed and efficiency. They're mostly used when controllability is important, or high force vs. speed. They can also make accurate positioning mechanisms, as well as continuous rotation.

Hydrodynamic transmissions are those involving fluid couplings, torque converters and the transmissions of diesel-hydraulic locomotives are quite different. They can transmit high powers (multi-thousand horsepower) at high speeds, and are lighter, simpler and more compact than comparable diesel-electric transmissions. Andy Dingley (talk) 20:11, 26 October 2017 (UTC)

One problem with hydraulics is that they behave differently at different temperatures. Fluid viscosity changes, volume changes, etc. Thus, a cold vehicle would drive very differently than a hot one. There are ways to compensate for this, within limits. StuRat (talk) 03:08, 27 October 2017 (UTC)

Hydraulic fluids in power transmission systems operate at a fairly constant temperature, set by their cooling systems and thermostats. They are heated by use plenty to rise above ambient. If they're in a cold climate, they may be pre-circulated beforehand, just to warm them. Andy Dingley (talk) 13:58, 27 October 2017 (UTC)

Yes, and preheating is fine for, say, a crane, but car owners neither want to wait to preheat the hydraulics nor pay to keep them heated at all times. So, one point against hydraulic cars. StuRat (talk) 22:45, 27 October 2017 (UTC)

There are no hydrostatic cars. Nor are there going to be. Andy Dingley (talk) 22:56, 27 October 2017 (UTC)

Agreed. Of course, if we are looking at this from a historic perspective, then hydraulics might have worked better with steam engine cars, since they also require preheating. StuRat (talk) 23:03, 27 October 2017 (UTC)

What possible benefit would a hydrostatic transmission convey to a steam-powered vehicle? They already have the advantages of a hydrostatic drive (the ability to generate considerable torque from zero speed, without needing any transmission) as they are. If you can cite all these "hydrostatic transmission steam cars", then please do so. Andy Dingley (talk) 10:01, 28 October 2017 (UTC)

I found Human Friendly Transmission, used by Honda in a few motorcycles. Roger (Dodger67) (talk) 06:16, 27 October 2017 (UTC)

That is a continuously variable transmission (i.e. a continuous-ratio gearbox), which makes up only a small part of the drivetrain. An important part of OP's question is why isn't most / all of the drivetrain made by hydro links, which presumably have less friction (hence power losses) than mechanical drivetrains. (I do not have a clue.) Tigraan^{Click here to contact me} 11:26, 27 October 2017 (UTC)

In case there's some confusion, Roger is the OP. Nil Einne (talk) 11:37, 27 October 2017 (UTC)

October 27

Zero living diet

Are there any foods that have never lived? Meaning, no animals, plants bacteria etc. Would it be possible to live on such diet? -- 193.64.221.25 (talk · contribs)

Water... most people might last a few weeks. Roger (Dodger67) (talk) 06:18, 27 October 2017 (UTC)

Only prokaryotes can do that, they have the enzymes to take in abiotic chemical compounds and make all the stuff they need. Eukaryotes are dependent on other organisms for their survival, e.g. they can't make vitamin B12, they don't have the enzymes for nitrogen fixation either, so they are dependent on prokaryotes for their amino-acids. Count Iblis (talk) 06:32, 27 October 2017 (UTC)

It is possible to make synthetic fatty acids [1] - mercifully, it doesn't seem to have caught on; I guess the odd-numbered ones did not even meet up to the standards of the trans fat era. Synthetic sugars are harder. [2] Vitamin supplements are an issue, yet some are produced synthetically. There is no theoretical reason why such a diet cannot be produced (though you might need to go off-planet to find carbon you are somewhat confident 'never lived'), but it would be exceedingly difficult, so I would not expect the first test subjects to live long. Also note that ethane, present on Titan, is metabolized by the rat [3] so at least some "foods" presently exist that match this criterion, though it would be poorly nutritious and a bit over-chilled on the palate. Wnt (talk) 11:03, 27 October 2017 (UTC)

There are many kinds of extremophiles that live on, for example, organic chemicals that seep into the oceans from mid-oceanic hydrothermal vents. Chemosynthesis would be the term. As to the main question, no, it is not possible for you as a person to live on food which has never lived. Excepting certain dietary minerals, which do not provide energy to your body, food entails life. All food must have been living at some time previous, for any reasonable definition of "previous". Some foods are currently living. Indeed, many raw plant foods we eat are alive while we consume them. --Jayron32 11:06, 27 October 2017 (UTC)

Can we say that plants have a diet of non-living food? I mean they just need water and minerals from the ground, CO2 in the atmosphere, and sunlight for energy. I guess the question is more about whether you accept that plants "eat" at all.— Preceding unsigned comment added by Lgriot (talk • contribs)

Well, that's it. We need to define "eating". I mean, I would define that as ingesting a substance for the purpose of obtaining energy and building materials. There are other forms of ingesting we do (drinking, smoking, taking medicine or vitamins) which we don't call eating. Wikipedia's article on eating specifically excludes most plants, since plants are autotrophs. If you change the definition of eating, then sure, you can define plants as eating. But really, if you can just change the definitions of words to fit your needs, you can "prove" anything with those words. --Jayron32 14:42, 27 October 2017 (UTC)

Note that plants depend on bacteria to do the nitrogen fixation necessary to make amino acids. Count Iblis (talk) 18:00, 27 October 2017 (UTC)

The answers to a similar question from 2014, Wikipedia:Reference_desk/Archives/Humanities/2014_August_14#Non-living_food, may be of interest.--Wikimedes (talk) 18:39, 27 October 2017 (UTC)

There aren't any foods currently consumed that have never lived, but it would be possible in principle in make some. Probably the easiest, as far as I can tell, is ethanol -- which in spite of its use as an intoxicant is actually a high-calorie food source. Other edible foods can be made by artificial photosynthesis or chemical synthesis, for example simple sugars such as glucose, but the process is very expensive. Looie496 (talk) 21:14, 27 October 2017 (UTC)

@ Looie496 What about milk and honey? 185.217.68.208 (talk) 07:14, 30 October 2017 (UTC)

There are many minerals which, by definition, are produced by inorganic processes. Sodium, iron, calcium, potassium, etc. These are essential parts of the diet, but obviously not sufficient alone. Of course, just like with carbon, they may have been part of a living organism at some point in the past. StuRat (talk) 22:50, 27 October 2017 (UTC)

• The relevant article is abiogenesis. Even if you hold the fringe panspermia theory, the first life to arise (or "arrive") here on Earth was, pretty much by definition, bathed in a sea of free, simple organic nutrients. Last universal common ancestor describes an organism that derived its energy using chemiosmosis, but this organism would have been quite a bit more sophisticated than the first living protocell. μηδείς (talk) 18:31, 29 October 2017 (UTC)

• See chemoautotrophy. There are archea at deep ocean vents that "eat" only inorganic chemicals that come out of the earth. This is not "food" for you or me, but it is for them, and is probably the only known thing that roughly counts as an answer to your question. SemanticMantis (talk) 18:52, 29 October 2017 (UTC)

October 28

How many N-receptors are there (2 or 3?)

I was reading different sources about the number of the N-receptors (nicutinic receptors) among the cholinergic receptors. The most of the sources say that there are 2 nicutinic receptors (N1 and N2) but other source says there are 3 nicutinc receptors: "Nicotinic receptors are found in the CNS, in autonomic ganglia, and in striated muscle. They are divided into N1, N2, N3-cholinoreceptors. N1 - and N2 -cholinoreceptors are localized in the CNS, N1 -cholinoreceptors – in ganglia, N2 -cholinoreceptors – in muscular synapses, N3-cholinoreceptors – in the adrenal glands. The mechanism of nicotinic action has been clearly defined." Is that correct?--212.90.60.81 (talk) 04:08, 28 October 2017 (UTC)

We have a detailed article about Nicotinic receptors (note spelling). It categorizes them into two major groups based on location—muscular vs neuronal—and then further into ganglion-type and CNS-type of neuronal. It not mention a type specific to adrenal-gland location and does not use N1/N2/N3 terminology at all. Could you cite the source you are quoting so we can see context and if it cites other refs for us to read? DMacks (talk) 04:25, 28 October 2017 (UTC)

• If you want other sources than our article, see "Mammalian Nicotinic Acetylcholine Receptors: From Structure to Function", most recent review I could find in two minutes on PubMed. Look at tables 1 and 2. Fgf10 (talk) 10:30, 28 October 2017 (UTC)

Physical exertion causing rheumatism

This comes from the 19th-century book that I referenced in the toothache question of Wikipedia:Reference desk/Archives/Science/2017 October 8. I've got someone born in 1811 who moved to Iowa in 1851 and lived there until his 1880 death, and about him it's said:

The exposure which he was required to endure in a new country and among scattered societies, caused inflammatory rheumatism, which completely wrecked his physical frame, and the last ten years of his life were spent in intense bodily suffering.

Can the environment or physical exertion cause rheumatism of any sort? Apparently it can't cause rheumatoid arthritis, since Rheumatoid arthritis#Risk factors for this autoimmune disease are all irrelevant for a preacher in 19th-century Iowa who rejected drinking and smoking as sinful. I'm guessing that our Iowa friend got some sort of illness along the way (per the first sentences of Rheumatism#Types), or that he had an autoimmune disease that simply started after he moved. Is this a reasonable conclusion? Nyttend (talk) 13:16, 28 October 2017 (UTC)

I think the article rheumatism is pretty clear -- it's a generic term for pain. Serious physical exertion might cause osteoarthritis, either directly or as the result of physical injury to the joints. Damage to the sacroiliac joint or to the spine itself might cause sciatica or related conditions. There are a lot of options and I certainly can't diagnose a sentence (and am not qualified to diagnose a patient either). But going from rheumatism to rheumatoid arthritis specifically seems like a vulgar error. Wnt (talk) 15:19, 28 October 2017 (UTC)

Without knowing where this unfortunate person was and the nature of the terrain, it's impossible to even guess. It's possible it might have been what we now know as Lyme disease. When I received the diagnosis of RA, I was told that there are hundreds of conditions that all get lumped together as "rheumatoid arthritis" for ease of discussion. What might shed light on whether it was rheumatoid arthritis is a trace of his descendants and looking at their medical history, to see if any of them had rheumatoid arthritis or not. (OR here, well it's not my research but... I am currently taking part in a clinical trial to establish the degree of hereditability of RA, and as part of that, I have found this horrible disease seems to have affected at least 4 out of the past 6 generations of my family, up to and including myself.) --TammyMoet (talk) 10:42, 29 October 2017 (UTC)

Time for Wow signal to reach Earth

Assuming it was genuine, approximately how many years it took for Wow signal to reach the Earth? If there's an RS, one might want to add it to the article. Thanks--212.180.235.46 (talk) 17:44, 28 October 2017 (UTC)

Depends on which star it (might have) come from. The article on Wow says that the closest easily visible star in the direction of Wow is Tau Sagittarii. The article on that star says that it is 122 light years away. But that is just a possible answer to your question,!of course. Attic Salt (talk) 17:54, 28 October 2017 (UTC)

And, in case it's not obvious, it would take a signal 122 light-years away 122 years to reach us, at the speed of light. StuRat (talk) 16:02, 29 October 2017 (UTC)

Part of the problem and mystery of the Wow signal is that the receiver wasn't really pointing at any nearby stars when the signal came in. Tau Sagittarius is the closest easily visible star to where the signal came from, but that means "closest" from our perspective. Closest if the heavens were a flat image.

If you look at the map on the Wow signal article, it came from one of the two red ovals on the star chart. (It was received by a pair of receivers, but the way they filtered the signal means they don't know which of the two receivers actually picked up the signal.) The red ovals are a bit to the north-west of Tau S.

If the signal really is extra-terrestrial and our data about it is correct, then either it came from a transmitter in deep space (a starship?) or it came from a star system incredibly far away. Much farther than Tau S. ApLundell (talk) 15:52, 30 October 2017 (UTC)

October 29

E-Z notation: why not just use "cis" and "trans" as infixes?

(Z)-1-Bromo-1,2-dichloroethene could just be bromotransdichloroethene.

Are there any cases in which cis-trans notation would still be ambiguous if -cis- and -trans- were used as infixes before pairs of substituents? For example, (Z)-1-Bromo-1,2-dichloroethene could just be called bromotransdichloroethene. (Note the advantage of also being able to eliminate the numeric infixes in that case, since 1,1-dichloro wouldn't be transdichloro.) Likewise, the haloalkene with SMILES C(/Cl)(\Br)=C/F would be 1-chloro-cis-1-bromo-2-fluoroethene. NeonMerlin 11:59, 29 October 2017 (UTC)

I think it is hard to answer this sort of "why didn't they do it like that?" question. The rules used have some arbitrary components. At this point though, practically, suppose someone introduces your rule. What does it mean? Well, sometimes you can use it, sometimes you might use it, often you would encounter things labelled with E/Z notation. So it means we have to learn your scheme and how to apply it to compounds like [4] with four different kinds of atoms attached to the double-bonded carbons (which is actually not recommended according to our cis-trans article) and whether the "cis" applies to the thing directly after it or the two things in the "di" or ... whatever. And then we also have to be ready to understand E-Z notation. Which amounts to more trouble to learn, more entries in the tables of synonyms in a PubChem entry (exponentially more, since this permutes with every other arbitrary decision we make between naming systems), more errors. I think many people would not be pleased to encounter this kind of creativity in their chemical closets. Wnt (talk) 15:52, 29 October 2017 (UTC)

This explains situations where cis-trans is different from Z-E. Cis-trans is a subset of Z-E notation, such that all cis are Z and all trans are E, but the inverse is not true. The Z-E notation, it should be noted, is formal IUPAC convention, where as cis-trans is more informal (i.e. the difference between "ethanoic acid" and "acetic acid") As noted, there is no meaningful way to answer a question "why didn't they". Because they didn't. This is the system. --Jayron32 12:18, 30 October 2017 (UTC)

Your first statement is not true either. Trans-2,bromobut-2-ene is (Z)-2,bromobut-2-ene, because the groups with the higher priority on each end of the double bond are CH₃ and Br respectively. So the E-Z convention compares the CH₃ and the Br, while the cis-trans convention compares both CH₃ groups, producing opposite results. Double sharp (talk) 13:04, 30 October 2017 (UTC)

Even more reason why there are two systems. Thank you, Double Sharp! Well answered! --Jayron32 13:23, 30 October 2017 (UTC)

Thank you!

As for the OP's original question: in principle, you could indeed build a consistent system this way. However, (1) it's not used by anyone, and (2) it seems to be more problematic to decode because cis and trans only encode relative stereochemistry, whereas E and Z use an absolute frame of reference from the priority rules, as can be seen from my previous example. But you can certainly be the judge: try decoding the molecule name (4E,6Z)-1,1,7-trichloro-4,6-dimethyl-1,4,6-nonatriene (an example I got from the wonderful resource Master Organic Chemistry), and then try writing its name under your proposal. I think you'll find that the need to constantly shift your frame of reference in the relative nomenclature and nest the "cis" and "trans" in such a case is not worth the backward compatibility for the simple cases. Double sharp (talk) 14:51, 30 October 2017 (UTC)

J. E. Hogarth

There is no direct reference to J. E. Hogarth in Wikipedia, or the WEB, except for indirect links that cite his published work as for example in Stephen Hawkings dissertation. Why is this?

Is he notable in the Wikipedia sense? If he is, then he will have been written about elsewhere (try libraries if not on the web), and if not then he doesn't merit an article here. Dbfirs 16:38, 29 October 2017 (UTC)

I think maybe not? Here [5] is all the records for JE Hogarth on Google Scholar. Many of those are clearly not a guy who Hawking would be citing in his dissertation. His most notable work is published in Proc. Roy. Soc. A in 1962 (PDF here [6], it's about the arrow of time, among other things, and it seems the sort of cosmological thing that Hawking would have been interested in. It has attracted only 130 citations since then. Now, bibliometrics alone cannot establish or rule out notability on their own, but honestly, that's just not a very big impact (e.g. I have a paper with around that many citations published in 2011, and I'm a total nobody as far as WP notability is concerned, even if a few famous folks have cited my work).

Other than that, I can see a record of his dissertation and abstract [7], and that he was an editor for a few years [8] for the Ontario Association for Mathematics Education, and a member of the Canadian Mathematical congress [9] SemanticMantis (talk) 18:47, 29 October 2017 (UTC)

If you search Google Books rather than Google Scholar, you will find at least one that describes his work rather extensively, so I think he meets the notability criteria. The real problem is that hardly any information about him. He was in the Math Department at Queen's University in Ontario for many years, and has children living in the area, but that's basically all I can find out about him. He doesn't seem to have published anything significant after 1963. Looie496 (talk) 18:53, 29 October 2017 (UTC)

From what is accessible using Google, the most detailed might be this. Curiously, or ambiguously it states: "Although Hogarth only published his analysis in 1962, it was generally known to many people before that time." I think there is mention of a thesis of him dated 1953, if that is correct I would be curious to know what was the situation precisely between 1953 and 1962. --Askedonty (talk) 19:37, 29 October 2017 (UTC)

I suppose it could go either way. For this kind of guy, we'd have to specifically apply Wikipedia:Notability_(academics)#Criteria, not just general notability standards. Maybe his "research has had a significant impact in their scholarly discipline", but that seems a little odd given his frankly thin publication and citation counts. Then again, it's quality not quantity that counts, so perhaps the book you mention could be used as an RS to demonstrate significant impact. SemanticMantis (talk) 14:32, 30 October 2017 (UTC)

October 30

Locomotive efficiency

What is the highest thermal efficiency ever achieved by a steam locomotive? I know their typical efficiency is only 5-10%, yet I've read somewhere that some of them (notably some of the later French De Glenn compounds) achieved an efficiency of up to 25% (at the cost of greatly complicating both operation and maintenance) -- is that true? 2601:646:8E01:7E0B:65AB:303D:F2EB:232 (talk) 06:16, 30 October 2017 (UTC)

Locomotive engines in particular face severe practical limitations that reduce their efficiency. Even battleships had to make some compromise in their reciprocating steam engines, for example few if any used quad expansion expansion engines. Even so the efficiency of their massive engines maxed out at 13%. Derived from "Ship Form, Resistance and Screw Propulsion" by GS Baker, published in 1920. So how could the necessarily compromised railway locomotives get double that? By going to a steam turbine possibly. But that incurs losses in the transmission. I suggest you challenge the 25% figure, it doesn't pass the sniff test. Greglocock (talk) 06:44, 30 October 2017 (UTC)

Coincidentally the highest efficiency I can find for a Andre Chapelon design is 12%. Greglocock (talk) 06:55, 30 October 2017 (UTC)

And 12-13% for Argentina https://static1.squarespace.com/static/55e5ef3fe4b0d3b9ddaa5954/t/55e637bee4b0bef289260255/1441150910433/%23+DOMS-2_PORTA_Argentina.pdf Greglocock (talk) 07:09, 30 October 2017 (UTC)

• The most efficient weren't the French de Glehn's, but rather Chapelon's larger 8-coupled locos, the 242 A 1 and 240P. Another couple of engineers worth looking at L.D. Porta in Argentina and David Wardale's Red Devil in South Africa. Much of this later work wasn't about thermal efficiency so much as improved mechanics (the developing technology of the time was offering useful developments here, such as roller bearings), and in more efficient combustion with worse fuels. Porta's Gas Producer Combustion System in particular. Koopmans. The Fire Burns Much Better. ISBN 1909358053. is an important text in this field.

A steam locomotive is first of all a locomotive: it has to move itself, it has to fit through the railway loading gauge. This has always been a limitation on their performance and the sophistication possible. As a result they always lagged behind marine and stationary engine practice. High boiler pressures, steam turbines, condensing and even superheating either didn't appear on locomotives or only later and with less success. Turbines in particular were a notable failure owing to the lack of a successful high pressure watertube boiler and the only one that was adequately reliable was the Turbomotive, the least technically adventurous of them. Andy Dingley (talk) 11:01, 30 October 2017 (UTC)

I found a project to rebuild a 1956 locomotive, ATSF 3463, to run on torrified biomass. The modernised boiler arrangement is being claimed to double the original thermal efficiency, although there is much scepticism [10]. Alansplodge (talk) 17:16, 30 October 2017 (UTC)

Zero Living Diet Pt2

I was intrigued by the question above. Unless I missed some nuance in the question, my immediate thought was "milk and honey". Neither of these has ever "lived". Sure they were produced by living creatures but they in themselves are not considered alive. Would this fit the OPs question? 185.217.68.208 (talk) 07:12, 30 October 2017 (UTC)

You'd have to ask the OP (193.64.221.25 (talk · contribs)) that question. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:31, 30 October 2017 (UTC)

Both of those things are mode from living things.

Honey is made from pollen. Pollen was certainly once alive.

Milk is less obvious, but it must ultimately came from whatever the cow ate. (Probably grass? Or corn?)

Of course, as Bugs points out, you'd have to ask the guy who wrote the original question if that "counts" for his purposes. ApLundell (talk) 20:50, 30 October 2017 (UTC)

Moist sodium chloride density data

What data sources are available for the density of moist ordinary salt (sodium chloride) samples as a function of water content and perhaps porosity or void fraction? (Thanks)--82.137.11.59 (talk) 10:43, 30 October 2017 (UTC)

At Manley’s Technology of Biscuits, Crackers and Cookies you can see the bulk density of granular dry salt 1.22 to 1.32. Using this and the density of sodium chloride crystals of 2.165, you could work out the void space that could contain water and then work out how much water would add what weight, and so get a new density for damp salt. See Bulk density to read about issues to do with density. Graeme Bartlett (talk) 12:02, 30 October 2017 (UTC)

It's not quite that simple, because some of the water will dissolve some of the salt and form a saturated brine. Because of this, the relationship is likely to be highly non-linear, and just a raw calculation of "filling the void space with water" is unlikely to work; it would work for an insoluble solid like sand, but for salt it gets quite messy to work it out by calculation. You could get a number assuming simply filling in the void space; but that number would bear little connection to the actual denisty. --Jayron32 12:12, 30 October 2017 (UTC)

Perhaps predetermining porosity of dry solid salt with liquids like mercury would be a workable variant? Or perhaps checking the plausibility of the assumption that solid dry salt has near zero porosity? An other aspect I think it should be considered and had in mind when formulating the above question is water activity in humid solid salt! I have put the question mainly to address the issue of water activity in this solid substance and to check the degree of non-ideality of the water salt solid mixture as non-ideal solution!

Considering these aspects, another question arises: How can the brine content in the possible void spaces in solid salt be determined?(Thanks)--82.137.14.216 (talk) 13:35, 30 October 2017 (UTC)

Sodium chloride, thankfully, has a relatively flat solubility curve, so the density of saturated brine is fairly constant at all temperatures from the freezing to the boiling point, 1.202 grams/mL That may be useful. --Jayron32 15:37, 30 October 2017 (UTC)

Isn't the rate of change in density with respect to the propotion of water a linear relationship at constant temperature and pressure, in the special case where the solution is saturated? Should the density lie on a straight line between the density at a concentration of 359 g/L and the density of pure salt at 2.165 g/mL? It could also depend on a energy minimum, whether or not the system has an energetic preference for a certain amount of water to be incorporated. Plasmic Physics (talk) 19:23, 30 October 2017 (UTC)

What's the average or median tidal range of the coast of the World Ocean?

For some reasonable definition of coastline and ocean. I always liked "where mean water level = mean sea level". Do small islands change the answer much through sheer numbers and often being far offshore where tides are smaller? Sagittarian Milky Way (talk) 14:03, 30 October 2017 (UTC)

There may be a real number for this, but I can't find anyone that has actually calculated it. I've checked several likely google searches, and I can't find anywhere that anyone has ever calculated a worldwide mean tide. The variation is highly dependent on where and when the tide is measured. Hypothetically it may be calculable. Realistically, I can't find any reference to help you figure it out. --Jayron32 15:35, 30 October 2017 (UTC)

Sorry, maybe I'm just being dense. Are you asking about the average (mean) difference in height between high and low tide, based on the sample of all the coastlines in the world? The coastline paradox still comes back to bite you, right? Whatever unit you use to determine how many points to measure (every x miles or millimeters of coastline) will affect your answer with the added bonus that the tides also affect some portion of river's edge deeper inland (as with a tidal bore). Matt Deres (talk) 16:31, 30 October 2017 (UTC)

• far offshore where tides are smaller - I would have thought this was "obviously" wrong because outside of areas where water flow is restricted (e.g. Gibraltar is a small passage to the Mediterranean Sea), sea level would simply follow the equipotential of gravitational energy (IIRC if you assume two point-like masses at the centers of Earth and Moon, it is an ellipse). It turns out that is not the case (example: the Azores have much less tide than Lisbon at the same latitude).

This and that indicates that the tide level is a matter of forced oscillation of the water masses in the ocean basins. It is therefore unlikely that there is an easy way to compute tide height at any given location.

You could pull a database of historical tide heights at a lot of locations where that is measured and average them, hoping that it gives a good proxy of the average tidal height (it probably isn't; for instance, ports are at places where tide is low and measurements are done where people are interested to have the data i.e. at ports). I was initially hopeful to find this in a reasonable format for free on the web, but my enthusiasm dissipated after reading this. The closest I found is [11] but that is a pdf format probably impossible to feed to a program. Tigraan^{Click here to contact me} 18:31, 30 October 2017 (UTC)

An OCR program could pull (digitize) the tide data from the pdf tables but the same data is more readily available ready digitized at [12]. Coastlines may be drawn at Mean High Water (on maps and charts), at Mean Sea Level (on maps showing sea depth) or at Lowest Astronomical Tide (on nautical charts), see Tide#Definitions. Harmonic analysis of tides was introduced in the 1860s by William Thomson (titled "Lord Kelvin" after the river near his laboratory) who built impressive mechanical Tide-predicting machines that employed Ball-and-disk integrators. Harmonic analysis offers the means to subtract all the oscillatory terms of a long-term (19-year, see Metonic cycle) Fourier series analysis to leave only the zeroth term corresponding to the mathematical average. Tidal prediction data thus obtained were kept secret during WW1 and WW2, which is understandable, were then made public, but then in the USA were removed from the public domain after the fact by SCOTUS in Golan v. Holder in 2012 - a ruling on which the WMF in collaboration with the EFF had words to say. Blooteuth (talk) 20:15, 30 October 2017 (UTC)

Finding Voyager 1 goes dark

When Voyager 1 runs out of power and we develop manned space travel past our planet's orbit, how easy will it be to find Voyager 1 to study it? I realize this is sort of crystal balling but maybe someone has thought of it before and did some research. †dismas†|^(talk) 18:34, 30 October 2017 (UTC)

Well, we know the trajectory quite precisely, but the problem is that the Trans-Neptunian objects aren't comprehensively mapped out, and there may be large objects Voyager will encounter. Now the chances of an impact are extremely small, but even the most modest of gravitational deflection could have a major effect on the location, over centuries. So, the time period elapsed would be important in knowing how great the error will be, and we also don't know how sophisticated our scanning devices will be by then. There's also the political climate to consider in the future. That is, would they really think retrieving Voyager was a good use of taxpayer money ? So yes, unfortunately, this does get into crystal ball category. StuRat (talk) 19:08, 30 October 2017 (UTC)

The two Voyager missions will start the process of shutting down according to the schedule here. According to that webpage (from NASA) in 2020-2021, NASA will begin powering down various science experiments on the probes to conserve fuel, and all science experiments will cease by 2025, however NASA will still receive telemetry data from the probes until about 2036, when all power to the probes will fail completely. --Jayron32 19:19, 30 October 2017 (UTC)

Also, you mentioned manned space travel, but such a task would be far better suited to a unmanned spacecraft. That is, unless we develop some way to get there much faster, such a mission would take years, and a human would need food, water, air, heat, etc., for all that time. (Considering that they've been flying away from Earth for over 40 years now, even if we had some way to get there 10 times as fast, that would be 4 years, and by then they would have moved on a bit further, and then we have to add the time to locate and retrieve the ship, and the return trip, so we'd be talking about some 9 years.) StuRat (talk) 19:31, 30 October 2017 (UTC)

There was an XKCD "Whatif" column about retrieving Voyager. [13] Unfortunately, it's one of the early ones that's not really referenced. But you can usually trust Randall Munroe's math. ApLundell (talk) 20:29, 30 October 2017 (UTC)

Excellent info. But what if a chemical rocket with planetary gravity assists was used to get part of the way there, with fast acceleration, then ejected, using an ion engine for the rest ? Hopefully that combo would cut the time down somewhat. StuRat (talk) 21:06, 30 October 2017 (UTC)