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December 31

Weapons of REAL mass destruction

Is it possible to cause the Baltic Sea and/or the Caspian Sea to explode? If so, about how big of an explosion (in megatons) could happen in this scenario, and how much damage on Russian soil could it cause? Is it possible to do the same thing with permafrost? 2601:646:8A00:A0B3:F484:63E7:CDC0:1004 (talk) 10:53, 31 December 2018 (UTC)[reply]

Well, the Schuylkill River and the Cuyahoga River have caught fire at various times, so anything's possible. ←Baseball Bugs What's up, Doc? carrots→ 11:17, 31 December 2018 (UTC)[reply]
Hydrogen sulfide produced from the microbial breakdown of organic matter may be delivered in small amounts from sewers to the seas mentioned but it is not explosive, merely smelly. DroneB (talk) 14:15, 31 December 2018 (UTC)[reply]
I think the OP might be thinking of the Lake Nyos disaster, which depended on carbon dioxide release - once an area started bubbling up, it had a positive feedback until a large amount of CO2 headed toward the village. Laboratory mice are euthanized the same way (also occasional hip kids who try dry ice in a hot tub). Hydrogen sulfide can be emitted during such events; I remember it, or other gases (I see our article mentions methane clathrates) was an explanation given for the Permian extinction but there were a lot of horses in that race and I haven't looked at the standings in some time. I remember long back reading the Black Sea has a high CO2 content deep down, so the idea using a shipload of dry ice to gas Turkey was an old fave, but I wouldn't bet on it. Most of these events are blamed on volcanism that has been priming waters to the point of a catastrophic turnover for some time, which is to say, they are repeated events; if you don't see that a body of water has done it before, I doubt puny humans can easily make it happen a first time. Wnt (talk) 15:18, 31 December 2018 (UTC)[reply]
Actually, I was thinking of the Status-6 first-strike nuclear torpedo which the Russians have developed (along with other ideas of theirs, such as nuking Yellowstone to make it erupt, or blowing up Iceland to disrupt the Gulf Stream), and looking at ways we might do the same things to them in retaliation -- my idea was to explode a nuclear weapon (say, a B83 fitted with a hydrostatic fuze) just below the halocline in the Gotland Deep and/or in the Caspian Sea in order to disrupt the halocline and cause massive outgassing of hydrogen sulfide (hopefully creating an explosive fuel-air mixture which the fireball would promptly detonate, hopefully causing a self-sustaining chain reaction which would cause most of the dissolved hydrogen sulfide to explode and create a veritable (and radioactive) tsunami heading toward St. Petersburg and Astrakhan and hopefully far inland). 2601:646:8A00:A0B3:F484:63E7:CDC0:1004 (talk) 02:55, 1 January 2019 (UTC)[reply]
How nice. Please find a forum somewhere else on the Internet for such ghoulish speculation. Acroterion (talk) 03:02, 1 January 2019 (UTC)[reply]
Please cite Wikipedia policy which prohibits discussion of this subject on here, or else retract your comment. 2601:646:8A00:A0B3:F484:63E7:CDC0:1004 (talk) 03:10, 1 January 2019 (UTC)[reply]
"The reference desk is not a chatroom, nor is it a soapbox for promoting individual opinions" and "The reference desk is not a place to debate controversial subjects." To extend, the refdesk isn't a forum for gleeful spitballing about "hopefully" creating radioactive tsunamis to destroy Russia in speculative forum-style posts. Your initial question has been answered, as far as I can tell, take the fictional speculation elsewhere. Acroterion (talk) 03:32, 1 January 2019 (UTC)[reply]
In that case, I have 2 specific questions here which have to do with science: (1) In the scenario I outlined above, will the gas (hydrogen sulfide or methane) detonate? (2) If so, will this detonation cause a self-sustaining and self-propagating chain reaction? 2601:646:8A00:A0B3:F484:63E7:CDC0:1004 (talk) 05:29, 1 January 2019 (UTC)[reply]
There are some things I don't know about this ... to be honest, I never even realized the Baltic Sea was brackish, even what our article calls "borderline freshwater", until now. (Except for the salty deep region described [1]) But what I do know is that H2S and H4C will not "detonate", because detonation implies that all the ingredients for a chemical reaction are present. Whether they could or would burn is another question, which I don't know the answer to. Methane, of course, is more dangerous if it doesn't burn, hence natural gas flare stacks. Creating a tsunami is a dicey proposition, since colossal energies from earthquakes often fail to produce one even when they are feared, and no nuclear weapon I know of can register 8 or 9 on the Richter scale. Supervillains might take heart that the source of a catastrophic tsunami might be predicted and manipulated, but if you look at a map of a feared feature [2], it's not like it has a "just push here" sign; who knows if even a lot of nukes would do it? Additionally, a radioactive source for a tsunami does not produce a radioactive tsunami, since a gravity wave does not literally mean that water propagates from source to destination, only that its displacement propagates. Wnt (talk) 16:16, 1 January 2019 (UTC)[reply]
So the answer is "probably not"? 2601:646:8A00:A0B3:F484:63E7:CDC0:1004 (talk) 01:37, 2 January 2019 (UTC)[reply]
The simplest way is to let an asteroid impact the target. NASA is investigating methods to avert asteroid strikes by changing the course of potential impactors, but the same methods can be used to steer an asteroid to hit a target on Earth. The asteroid that will be made to hit Earth doesn't have to be targeted directly, one may seek out a smaller asteroid whose course can be changed to hit a larger asteroid that will in turn hit the Earth. For the purpose of avoiding collisions with the Earth, I've shown here that this method to target smaller asteroids to hit the larger asteroids of interests, can be more practical than trying to deflect the larger asteroid directly. Count Iblis (talk) 19:27, 2 January 2019 (UTC)[reply]

Is superheated water a unique phase of water?

If the phase transition to superheated water only occurred when water temperature exceeded 100°C, then water would never superheat. Boiling would PREVENT superheating. Therefore, water must completely convert into the phase that can superheat BEFORE water can superheat.

Certain transitions between phases do not necessarily require latent heat. The phase transition from water with a 100°C boiling point to water that can superheat occurs when pure water is not in a scratched container and is vibration free. Conversely, vibration or a scratched container can convert the phase that can superheat into the phase with a 100° C boiling point.

“However, once the water is disturbed, some of it violently flashes to steam, potentially spraying boiling water out of the container.”

Disturbing the superheated water triggered conversion to the phase with the 100°C boiling point. The vapor is 100°C because the phase with the 100°C boiling point is vaporizing.

The phase that can superheat is not boiling. If superheated water itself indeed boiled, its vapor temperature should be the same as its water temperature and boiling should occur at the rate external heat is added.

“Even when the water temperature was over 105°C, the steam temperature was only a few tenths of a degree over 100°C (Marcet 1842, 404-405).”

The phase that can superheat has a lower melting point than the phase that boils at 100°C. Likewise, there are 18 known solid crystalline phases of water, each with their own phase transition temperatures and pressures.

“Extremely pure, supercooled water stays liquid below 0°C and remains so until applied vibrations or condensing seed doping initiates crystallization centers. This is a common situation for the droplets of atmospheric clouds.” — Preceding unsigned comment added by Vze2wgsm1 (talk • contribs) 11:30, 31 December 2018 (UTC)[reply]

Vze2wgsm1 (talk) 11:32, 31 December 2018 (UTC)[reply]

Superheated water isn't a different phase but there is evidence that liquid water is really strange in that there are two phases of liquid water with a crossover between 40°C and 60°C. Dmcq (talk) 13:23, 31 December 2018 (UTC)[reply]
@Dmcq: do you want to say more about that? I don't know what you mean. --Trovatore (talk) 01:44, 1 January 2019 (UTC)[reply]
[3], in particular there are some studies linking this to the temperature at which proteins denature if you look at the papers citing it. Dmcq (talk) 02:04, 1 January 2019 (UTC)[reply]
Pressure–temperature phase diagram of water. Liquid water boils when its vapor pressure exceeds ambient pressure plus pressure of surface tension around newly forming vapor bubbles. In undisturbed water with only tiny vapor bubbles, their surface tensions are high enough to delay boiling i.e. allow Superheating of the liquid. This is not creation of a new phase, it is displacement i 2 o'clock direction from the "Boiling point at 1 atm" shown. DroneB (talk) 13:52, 31 December 2018 (UTC)[reply]
Boiling does prevent superheating. When you heat pure water past its proper boiling point on that phase diagram (100 C at 1 atm), then logically two things can happen. Either it turns into a gas, in which case you say it boils, or it stays liquid, in which case you say it superheated. The key fact that matters here is that boiling doesn't happen on a single-molecule level; it requires nucleation. Think of an angry mob facing off against a line of cops -- there has to be somebody to throw the first stone. If your water isn't very pure, there will be some "troublemakers" around to make sure that happens as soon as it can, but if it is totally homogeneous then you can see some stranger behavior. You can be at a point where a large bubble would get bigger, but no bubble exists to begin with. I recall an intro chem lab where my entire reaction in petroleum ether abruptly took to the air - bumping (chemistry) - leaving reactants/product all over the benchtop and what was almost immediately a dry Erlenmeyer behind. Wnt (talk) 15:26, 31 December 2018 (UTC) Does not apply. Petroleum ether is not a pure compound. Vze2wgsm1 (talk) 02:11, 1 January 2019 (UTC)[reply]

For all pure compounds, boiling occurs at temperature and pressure combinations where added thermal energy converts into heat of vaporization, instead of increasing enthalpy. Each of these temperature/pressure combinations are precise.

A given pure chemical compound has only one normal boiling point, if any, and a compound's normal boiling point and melting point can serve as characteristic physical properties for that compound, listed in reference books.

A requirement for nucleation sites would make boiling points imprecise. Therefore, no pure compound requires nucleation sites to initiate boiling.

Superheated water contains more enthalpy than water that boils at 100 C, without becoming less stable than a vapor molecule. The phase of water that boils at 100 C becomes less stable than a vapor molecule if temperature exceeds 100 C. Therefore, water that can superheat is a different pure chemical compound than water that boils at 100 C.

Note: The boiling point of a pure compound is not necessarily a function of surface tension. Adding surfactants to change water’s surface tension does not necessarily lower water’s boiling point.

“They found that adding surfactants to the water jet did not change the incipient boiling point.” Vze2wgsm1 (talk) 01:34, 1 January 2019 (UTC)[reply]
I think you're probably getting confused by that paper, 'supercritical' is not the same as 'superheated'. Dmcq (talk) 12:03, 1 January 2019 (UTC)[reply]
In the paper, the author used the word supercritical was with respect to Nusselt numbers, not to the phase of water with the high Nusselt numbers. The water in the supercritical region was (initially) subcooled.
“Boiling was not present in the supercritical region of flow partly because water entered the channel as a subcooled liquid, and partly because the supercritical flow field had high enough heat transfer coefficients to keep the disk surface below the level of superheat needed to induce boiling.”Vze2wgsm1 (talk) 14:48, 1 January 2019 (UTC)[reply]

What are sweet peas?

This is related to my seeing Popeye (film) for the first time. When I went to Sweet pea I was expecting a plant that we can eat, but the article says we shouldn't eat it. However, I have heard for years about "sweet peas", including a product by that name that was related to a pricing game on The Price Is Right. Nothing in the pea article seems to suggest there is such a thing that we can eat.— Vchimpanzee • talk • contributions • 18:21, 31 December 2018 (UTC)[reply]

Could this be the snow pea? Its scientific name is P. sativum var. saccharatum, i.e. "sugared" or something like that; in German it is called de:Zuckererbse, i.e. "sugar pea". --Wrongfilter (talk) 19:34, 31 December 2018 (UTC)[reply]
I don't know. Snap pea comes closer but I don't see anything in the article calling it "sweet pea".— Vchimpanzee • talk • contributions • 20:13, 31 December 2018 (UTC)[reply]
It's called sugar snap pea per our article or simply sugar pea [4] [5] [6] [7] en:wiktionary:sugar pea sometimes. I guess it's possible some people may call it sweet pea, but I doubt it's very common. Nil Einne (talk) 22:42, 31 December 2018 (UTC)[reply]
Our article on the Popeye character Swee'Pea states that the name derives from sweet pea (Lathyrus odoratus). The name "sweet pea" in horticulture normally refers to this plant, rather than to a sweet-tasting edible pea. My guess is that the "sweet" part of the common name is referring to the scent of the flowers, not the taste of any fruit (peas). PaleCloudedWhite (talk) 23:07, 31 December 2018 (UTC)[reply]
As with the flowering plant called Sweet William. ←Baseball Bugs What's up, Doc? carrots→ 03:50, 1 January 2019 (UTC)[reply]
To confirm PaleCloudedWhite's guess, the OED says that the Sweet Pea was 'formerly called sweet-scented pea'. AndrewWTaylor (talk) 10:23, 1 January 2019 (UTC)[reply]

What CO2 percent is needed to boil the ocean?

If you added it in a climatological instant like a year. How long would it take to start and finish boiling? How long after that before thermal equilibrium? Would any carbonate rocks survive? How hot would Challenger Deep and Mount Everest get? Sagittarian Milky Way (talk) 22:48, 31 December 2018 (UTC)[reply]

I'm assuming you mean, 'what CO2 percent in the atmosphere...'? PaleCloudedWhite (talk) 23:19, 31 December 2018 (UTC)[reply]
"Numerical climate models as well as carbon isotope measurements from preserved Ordovician soils suggest that atmospheric levels of carbon dioxide during the period were 14–16 times higher than today... How continental glaciation could have formed when carbon dioxide levels were so high has been a paradox."[8] If you look at the various theories, you will find a vigorous debate about glaciers forming vs. glaciers melting during this high CO2 period, but the debate is about temperatures slightly above freezing vs, temperatures slightly below freezing, never about temperatures near boiling.
As our article on Runaway climate change says, "an extreme moist greenhouse might cause an instability with water vapour preventing radiation to space of all absorbed solar energy, resulting in very high surface temperature and evaporation of the ocean. However, simulations indicate that no plausible human-made greenhouse gas (GHG) forcing can cause an instability and baked-crust runaway greenhouse effect." --Guy Macon (talk) 00:38, 1 January 2019 (UTC)[reply]
The following is a lot more speculative, but our article on Snowball Earth says "The carbon dioxide levels necessary to unfreeze Earth have been estimated as being 350 times what they are today, about 13% of the atmosphere."
Also our article on Carbon dioxide in Earth's atmosphere says "Concentrations of CO2 in the atmosphere were as high as 4,000 parts per million (ppm) during the Cambrian period about 500 million years ago to as low as 180 ppm during the Quaternary glaciation of the last two million years... Global annual mean CO2 concentration has increased by more than 45% since the start of the Industrial Revolution, from 280 ppm during the 10,000 years up to the mid-18th century to 410 ppm as of mid-2018." The earth has never experienced boiling oceans since the time during and shortly after the surface was molten lava, but we have seen periods of little or no glaciation, alternating with ice ages. --Guy Macon (talk) 00:51, 1 January 2019 (UTC)[reply]
Note the relevant article/term is runaway greenhouse effect or runaway climate change. It seems to be relatively out of favor as a possibility lately, but some do say it could happen. I've been waiting for old artifacts from Venusian exploration missions to turn up and provide some insight on this... really was holding out some hope for the Dawn mission... Some of the NASA maps I've seen lately put Earth right at the inner edge of the Sun's habitable zone, FWIW. Note that the question is difficult and would require simulation because to get to the boiling of oceans implies not just a few degrees of heating but a "runaway" proper, i.e. that the increased water vapor acts as a greenhouse gas more than the increased clouds act to cool the planet. At the same time, the remarkable CO2 levels quoted from long ago have to be taken in context of the faint young Sun paradox; it isn't clear nearly that much would be needed now. Wnt (talk) 05:27, 1 January 2019 (UTC)[reply]
Very roughly, a runaway moist greenhouse might start about 47 C in the global mean temperature according to runaway greenhouse effect. That's about 33 C warmer than today. Assuming a climate sensitivity of ~3 C/doubling of CO2, that would imply something like 2000 times as much CO2 as today. Which translates to adding enough CO2 that roughly 1/2 of the atmosphere would be CO2 (assuming other constituents stay the same). At that level, all macroscopic oxygen-dependent life would suffocate before they had a chance to boil. Dragons flight (talk) 11:21, 1 January 2019 (UTC)[reply]
If tenths of a bar of CO2 was suddenly added would enough of the locked-up methane be released before its atmosphere residence time to matter? Sagittarian Milky Way (talk) 14:24, 1 January 2019 (UTC)[reply]
@Dragons flight: That article describes an effect per "doubling", but as far as I see they only look at the one data point of double some baseline. I don't think they're making a claim for a logarithmic effect, are they? At least, I don't see why the effect would be logarithmic, though I don't know it wouldn't be either. Given the degree of uncertainty for even one data point, in any case, I would be skeptical that the curve of many can be predicted beyond the parameters of existing simulations. Wnt (talk) 16:04, 1 January 2019 (UTC)[reply]
The radiative forcing of CO2 is approximately logarithmic. For more complete expressions, I would refer you to Table 6.2 of this IPCC chapter [9]. The logarithmic response arises (primarily) because the radiation absorption on the wings of the CO2 absorption bands evolve approximately exponentially with distance from the center on the band. The climate response (e.g. 3C) to a given radiative forcing is quite uncertain (due largely to various feedbacks), but the radiative forcing part as a function of CO2 actually isn't very uncertain (at least not at normal concentrations). I would however assume that there is a very large uncertainty with extrapolating to thousands of times modern CO2 levels, but then I also assume that SMW isn't really in need of a very precise answer. Dragons flight (talk) 18:02, 1 January 2019 (UTC)[reply]
Thanks! That chapter looks like the Real Deal for understanding this stuff, and quite a lot of it. Wnt (talk) 20:53, 1 January 2019 (UTC)[reply]

January 1

Are large rings of pure oxygen possible?

What about this? Sagittarian Milky Way (talk) 19:32, 1 January 2019 (UTC)[reply]

Solid oxygen describes allotropes of four and eight oxygen atoms per molecule. The graphic you have is some sort of crown ether, but with all those oxygens on each carbon atom (gem-diol) I would be very skeptical about its stability. Wnt (talk) 20:59, 1 January 2019 (UTC)[reply]
Long chains of oxygen are endothermic at standard pressures. Energy is released to make dioxygen. They may be stable at low temperature. Trioxygen difluoride and bis(trifluoromethyl) trioxide both exist. For your "what about" there are organic esters of tricarbonate. Your structure will rapidly turn into water and carbon dioxide unless you can freeze it. Under high pressure carbon dioxide may behave more like silica. Graeme Bartlett (talk) 21:04, 1 January 2019 (UTC)[reply]
Cyclic and linear polymers of -CH2-O- are known (see polyoxymethylene and Formaldehyde#Forms of formaldehyde). Various analogs with chains or functional groups instead of the H on the C are known also, but gem-diols (especially the hydrate of a carbonate ester) are quite unstable. DMacks (talk) 14:37, 2 January 2019 (UTC)[reply]

January 2

Animals with head first delivery preferred?

What animals other than humans have the preferred delivery being head first (as opposed to for example a cow, for which the front hooves is the preferred first part of the animal to deliver.Naraht (talk) 01:18, 2 January 2019 (UTC)[reply]

Well, the other great apes and indeed a majority of simians. This is actually an interesting evolutionary matter, as live birth is believed to have evolved independently in various parts of the tree of life on at least a couple hundred occasions, and the variations on the physiological morphology are remarkable as a result. There are a number of different factors which are believed to have influence which species evolved head-first birthing (meaning superior portion of the body first, which a strong but by no means absolute majority of live birth species use), but by far the most significant is cephalo-pelvic ratio: basically, the higher this ratio the more likely the species is to require this form of birthing, and then at the high end of that spectrum (especially where mammals are concerned) are mostly clustered the cranial-first species. Of course we must also account for aquatic live-birth species, of which there are quite a few, most of whom have no legs to compete with the head. Snow let's rap 12:06, 2 January 2019 (UTC)[reply]
Thank you very much. I am excluding the aquatic in this. What is the split within the simians?Naraht (talk) 14:59, 2 January 2019 (UTC)[reply]
You're very much welcome. As to your further inquiry, I'm unaware of an obvious single source that aggregates that data, and could not immediately find one, but it's likely to be out there somewhere. Here are a few sources which at least provide detailed consideration of the relative physiological proportions in various simian species, though a majority of them are behind paywalls which may restrict your access depending on your research portal resources: [10], [11], [12], [13], [14], [15].
My suspicion, based upon what I do know about parturition across mammalian species, is that the vast majority of all simians birth cranium first. Of course, you should take that uncited statement with a grain of salt, but there's actually a generally reliable test for figuring out which species are going to birth which extremities in which order: Because childbirth is an exceptionally risky process for both parent and offspring in most all species, there is a substantial selective pressure to ease and expedite the process to the extent the morphology of the child allows. As such, in mammals there is a pronounced, almost universal preference for births to proceed in the order which minimizes the maximal circumference to which the vagina will be stretched, thus minimizing potential trauma to the mother and child. So obviously with most bipeds, allowing the hands and arms to come out extended alongside the cranium would increase the radius and also put dangerous pressures upon parts of the body already tightly constrained by pressure that is already at the high end of all animal parturition. Whereas with most livestock species, to borrow your example from above, the most complicated and problematic method would be too have the legs pressed downwards against the trunk of the body, which is why most all avoid this by having the forelegs precede the head. Now this is not an absolute rule, because there are other considerations and many species actually have room to spare in the vagina (well, at least compared against humans, who are at an extreme end of the spectrum), including some simians. But as a general rule, you can look at a species, consider it's biomechanics (which way the extremities most naturally flex and which profile would allow for a minimal demand upon increase in the diameter of the birthing canal) and make a rough reliable guess for whether they are likely to come out cranium first or superior limbs first. Snow let's rap 23:16, 2 January 2019 (UTC)[reply]

January 4

Is there any evidence that biology is reducible to physics

Reductionism has worked very well for technology but why do so many people assume everything can be reduced to subatomic particles? There are intractable problems like how the first cell formed, consciousness, free will, if reductionism is to be believed. Is there any research along the lines of "strongly emergent" behaviours of complex systems? By strongly emergent i mean something that's not predicted to exist given the laws governing the constituents, i.e. something completely new comes into existence at sufficient complexity. Have people tried to calculate how the simplest bacterium behaves according to laws governing atoms? — Preceding unsigned comment added by Money is tight (talk • contribs) 04:25, 4 January 2019 (UTC)[reply]

As mentioned in this talk, for simple microbes there does exist a complete description. But, with hundreds of thousands of different enzymes, the "flow chart" of a microbe is huge, it fills tens of thousands of pages. Count Iblis (talk) 04:49, 4 January 2019 (UTC)[reply]
Bear in mind that reductionism is not necessarily about arriving at the most efficient description of a given phenomenon--it's just an attempt to isolate and definite its constituent features, ideally in terms of universals that can be used for all other like phenomena, or (when it comes to physical reductionism, potentially all phenomena). So, to answer the query of your first sentence, the effort is based not so much in an "assumption" that everything can be reduced to a discussion of such constituents--no sensible empiricist working from first principles would operate their inquiry in that way--but rather upon a testing of that hypothesis. And so far, with one deeply perplexing exception, all biological functions have proven amenable to description in terms of physics. The one exception, which you allude to in your inquiry, is something we have such a difficult problem even conceptualizing, that we can;t reliably say whether it is a property (emergent or otherwise) of biology or physics--although we have a profound propensity/bias to frame it in those terms. I am, of course, talking about consciousness. Because it is (not just in terms of biology or psychology, but indeed the entirety of science and empirical human inquiry) the one phenomena that has never been captured or explained by a physical model in any concrete fashion, at any level, this quandry has been given (rather appropriately, I feel) the forbiding title of the the hard problem. And it is indeed something so incredibly different and alien to the empirical method, that some philosophers and cognitive scientists surmise that it is in some sense illusory (whatever Descartes would say to that) or something so far beyond the parameters of what our mental organs are designed to grapple with, that we will never understand it in even a rudimentary fashion. But as to everything else, reductionism works as well for biology as for any other physical system--the complexities simply require a broader canvas to orient and make sense of, with a lot of work still to be done to fill in the gaps--a task which may realistically span eons, if it is resolvable at all. Snow let's rap 05:41, 4 January 2019 (UTC)[reply]
Just as an addendum, OP, despite my comments above, which might reasonably be received as a full-throated defense of reductionism, I do not mean to suggest it is the only (or even the most effective) empirical model for physical systems, only that there is not fundamental reason why, as a per se matter, it cannot describe all biological phenomena. However, for an alternative model, you might consider looking into systems theory, which is very much in the vein of describing emergent properties of complex systems. Fritjof Capra, one the populizers of this field of thought, wrote a number of popular science works surveying its development, and one of them is focused on biology in particular. Alas, we have no article for it (perhaps I should fix that), but the title is Web of Life; it could be a good place to start regarding your interests in this area. Snow let's rap 05:55, 4 January 2019 (UTC)[reply]
Really? There has been calculation of the trajectories of each atom in a cell and it agrees with the observed movement? May I see a reference? — Preceding unsigned comment added by Money is tight (talk • contribs) 09:23, 4 January 2019 (UTC)[reply]
You're confusing the question of whether a model is in principle capable of describing a phenomena with the question of whether one has the ability to perform a given calculation--two very different matters. From the start through the finish of your original post, you framed the biological question as fundamentally different from other physical phenomena in terms of whether or not they could be reduced into fundamental constituents governed by the same basic physical laws as the rest of matter. And unless you are looking for some sort of answer steeped in quasi-mysticism, there's just no reason to believe that's so, and there's nothing in modern theoretical physics (whether it is reductionist or systems based) which suggests as much. The only difference between the only two examples of application you raise--the vaguely defined "technology" and a human cell--is the orders of complexity involved in the specific object or process observed. Again, that's a matter of calculation restraints, not any flaw of the model itself, and I believe I made it pretty clear in my first response that the distinction is between efficiencies when one compares more or less reductive methods of description of a given closed system against others. But more to the point, friend, if you want to be snidely dismissive of an answer that isn't the one you wanted, seconding your opinion of how limited a fundamental ontological branch of physics is, I'll just leave you to the assistance of all of the other people who have rushed to take some time out of their day to give you a considered answer and point you to some resources.... Snow let's rap 10:50, 4 January 2019 (UTC)[reply]
Oh, but I see from reviewing your contrib history that this is not a topic you were looking for information on, but in fact a topic you are persistently trying to create a debate around, across numerous spaces on this project over the course of years. Please understand that the RefDesk, and Wikipedia broadly, are WP:NOTAFORUM for you try to use to argue your metaphysical perspectives on. This desk is for genuine inquiries, not your efforts to set up someone to espouse a perspective you disagree with, so you can attempt to score a discursive victory. This has already been explained to you previously, I now see. Please respect the scope and purpose of this space. There are plenty of forums online for you to advance and argue your beliefs at length--this is not one of them. Snow let's rap 11:10, 4 January 2019 (UTC)[reply]
I was genuinely asking for a link about any strongly emergent process, after watching this https://www.youtube.com/watch?v=GVL2Y5z2jLU and knowing the severe problems with reductionism. All you did is link me to biophysics article and claim all of biology except for consciousness has already been proven to be derivable from interactions between atoms. I ask for link then you get so hurt that you spend the time to go through my posts just to cook up some insults so you can feel better about yourself... All I can do is lol. — Preceding unsigned comment added by Money is tight (talk • contribs) 11:54, 4 January 2019 (UTC)[reply]
There is an article "Reductionism in Biology" in the Stanford Encyclopedia of Philosophy. There is no proof that biology can be reduced to physics but there is no proof it cannot. I suppose the reason that people assume reductionism is possible is that organic objects have been observed to respond to physical actions in the same way as inorganic ones. It requires the same effort for example to transport organic and inorganic cargo of the same weight. There seems to be implicit in your question whether a resolution of this issue would have any metaphysical implications, specifically whether it could prove or disprove religious claims. The answer is no. (PS - please sign your posts.) TFD (talk) 13:43, 4 January 2019 (UTC)[reply]
The point is, this space is for people seeking information, while your previous history of getting into fights about the nature of an immaterial existence beyond the body all across the project as basically your only activity here for years makes it clear that that you are actually here to find opponents/a debate--and you're not going to get either here. You very clearly were asking about something you expected responders not to be able to provide to your satisfaction: you ask your queries with the vague "Have people tried to calculate how the simplest bacterium behaves according to laws governing atoms?", to which the obvious answer is "yes, of course" at which point you get to swoop in with "Oh come on, obviously no one has tracked the motion of every subatomic particle in a cell", which is something you clearly already knew and just wanted an excuse to say. Again, this space is for people who are requesting new information on a topic, not an excuse to argue about spiritual or philosophical beliefs for which they already know the standard arguments, which they want to engage in a WP:BATTLEGROUND over.
Your question was disingenuous and you're just trying to re-engineer the same debate you apparently have everywhere you go on Wikipedia--on talk pages for articles about near-death experiences to those about metaphysics and indeed, on this very page previously--despite being told this project isn't the place for that kind of engagement. It is WP:disruptive to the point of being a form of WP:NOTAFORUM trolling, since you clearly know this is, under our policies, not an acceptable use for a talk space and yet it is all you are here to do. Please desist. Snow let's rap 17:14, 4 January 2019 (UTC)[reply]
If this isn't a forum, this isn't a moot court either. There are some good answers here but please, take the nastiness and WP:SILLYTERMS to talk or something. Wnt (talk) 22:03, 4 January 2019 (UTC)[reply]
Wnt, this isn't about nastiness, it's about WP:NOTHERE and WP:DENY. And why would I take this talk; I'm not trying to give an opening to any guideline skeptics to open that TP's five-hundreth tedious, no-consensus debate about liberalizing our WP:NOTAFORUM standards. I commented here because this is where this user is engaged (for the moment) and therefore this is the appropriate place to tell him this is not what the RefDesks are for. Aside from that, I'd said what I intend to say on the matter, but I'll add this: I really suggest you look through the diffs before you consider feeding this user's behaviour--you'll not be doing the desks any favour and you'll be steering them that much closer to a block or topic ban. Snow let's rap 01:24, 5 January 2019 (UTC)[reply]

Can blood vessels damaged by hypertension repair themselves?

I personally think the damaged inner lining of artery in which inducers like hypertension left cracks on the vessel wall that later allowed buildup of plaque (lipids) can eventually heal on their own if the inducer such as hypertension is no longer present just like how a bleeding-wound healing works when we don't rub it or irritate it. If a cut or damaged vessel can't be regenerated, then those bleeding wounds on the skin involving much broken vessels we have all ever had in childhood shouldn't have been able to heal.

I wonder which article to read in Wikipedia that gives in-depth introduction to damaged blood vessel wall recovery? Thanks! --It's gonna be awesome!✎Talk♬ 13:52, 4 January 2019 (UTC)[reply]

I would try to start at wound healing or Regeneration in humans and check out ongoing links there. For more specific Information you may have to search the WWW.
Anyway, since the exact cause of Atherosclerosis (plaque builds up inside your arteries) is still considered to be unknown to science, some answers to that part of your questions may be more speculation than science. --Kharon (talk) 15:33, 4 January 2019 (UTC)[reply]
Thank you for the productive response! --It's gonna be awesome!✎Talk♬ 16:11, 4 January 2019 (UTC)[reply]
Everything in your body, including your arteries are constantly being repaired in response to damage done. Biological systems are dynamic systems not static systems that gradually wear down. Any long term degradation of a system in your body is the result of the net balance between wear and tear and the repairs being slightly negative. So, if you remove a source of wear and tear in your body then usually the system will improve. E.g. atherosclerosis is not simply the result of a long term deposition of plaque on artery walls, it is the dynamic equilibrium between plaque buildup and plaque removal being shifted too much toward plaque buildup. Under normal circumstances both processes occur at quite high rates, but plaque removal is more effective so arteries of animals tend to not have any plaque. When the first heart-lung machine was invented, the medical scientists were surprised to find that blood circulating in the pipes of the machines had a large amount of blood clots in them after just a few minutes. This shows that the blood vessels in your body are not simply inert pipes. This is why people who get angioplasty and are fitted stents need to get anti-platelet medication for the rest of their lives. Count Iblis (talk) 19:43, 4 January 2019 (UTC)[reply]
Yes, but the process of wounding and healing is inefficient, which is why scaring is a thing. The repair the body makes in response to stress, damage, injury, etc. is almost always inferior to what would have been there had the damage not occured in the first place. In general, the microscopic accumulation of these processes of damage and repair is senescence, and most living multi-cellular organisms undergo these problems to one extent or another. The body cannot go one forever, because the processes that created the body are not the same processes that repair the body. --Jayron32 20:38, 4 January 2019 (UTC)[reply]
Thanks both of you for the informative replies. --It's gonna be awesome!✎Talk♬ 09:27, 5 January 2019 (UTC)[reply]

Australian Snakes - Origin ?

How did the ancestors of modern Australian snakes get to Australia across Wallace's Line? It is my understanding that snakes are thought to be a monophyletic clade, so that the ancestral reptiles either evolved elsewhere and went to Australia or evolved in Australia and went elsewhere. Wallace's Line has been a barrier to placental mammals since before the evolution of placental mammals. (When Europeans "discovered" Australia, it had two placental species, C. dingo and H. sapiens, and we know which of them built boats.)

This would seem to imply either that snakes are older than placental mammals and crossed to Australia when there was a land bridge across what is now Wallace's Line, or that there is some alternate explanation. The alternate explanations that come to my mind are that aquatic snakes crossed to (or from) Australia and evolved back to terrestrial life, or that snakes arrived by rafting or similar accidental transport. Robert McClenon (talk) 20:58, 4 January 2019 (UTC)[reply]

  • Rafting. Abductive (reasoning) 21:13, 4 January 2019 (UTC)[reply]
  • (ec) The argument is not conclusive - it may be that placental mammals did not migrate to Australia for some other reasons (e.g. unsuitable climate, or origin in a very different location and not having spread there before the Wallace Line became a barrier). Indeed, Wallace Line says that the deep water channel has been a barrier for "over 50 million years", while "true placentals may have originated in the Late Cretaceous around 90 MYA, but the earliest undisputed fossils are from the early Paleocene, 66 MYA, following the Cretaceous–Paleogene extinction event" (from Placentalia#Evolution). Snakes go back at least 90 million years, so probably could have spread to Australia long before the Wallace Line became a barrier. Indeed, a lot of interesting continental movement happened during the time snakes have been around - it's hard to imagine 1e8 years... --Stephan Schulz (talk) 21:19, 4 January 2019 (UTC)[reply]
As I said, either rafting or a land bridge. No suggestion of swimming. Robert McClenon (talk) 23:39, 4 January 2019 (UTC)[reply]
There are variety of families, but none endemic to Australia. This means it can only, only, only be rafting. Abductive (reasoning) 01:44, 5 January 2019 (UTC)[reply]
This paper may be of interest, although it deals with all snakes, rather than just Australian ones. The "biogeographic reconstruction" section on page 19 discusses the likelihoods of snakes crossing water barriers of various different sizes. Mikenorton (talk) 21:52, 4 January 2019 (UTC)[reply]
Thanks. Robert McClenon (talk) 23:39, 4 January 2019 (UTC)[reply]
Robert McClenon, "two placental species", and the rest. cygnis insignis 22:26, 4 January 2019 (UTC)[reply]
User:Cygnis insignis? What do the two placental species have to do with the snakes? The snakes were already there. If you mean that how H. sapiens arrived is just another oceanic dispersal, that is one way of viewing things. Robert McClenon (talk) 23:39, 4 January 2019 (UTC)[reply]
Robert McClenon, excuse me being unclear, there are many placental mammals (Placentalia). Lots of them, the statement at the outset is incorrect. cygnis insignis 23:44, 4 January 2019 (UTC)[reply]
What other placental mammals were there in Australia at the time of its "discovery" by Europeans? Robert McClenon (talk) 01:42, 5 January 2019 (UTC)[reply]
I assume bats would have made it to Australia, as they did to more remote NZ.-gadfium 03:04, 5 January 2019 (UTC)[reply]
Okay, thank you. Two land placental species, then. Robert McClenon (talk) 04:51, 5 January 2019 (UTC)[reply]
According to Fauna of Australia#Placental mammals, there were at least two families of bats (it's a little unclear from the article how many were present prior to European influence), and many species of rodents, with 14 genera from five million+ years ago, and another seven species of rats from only one million years ago.-gadfium 05:17, 5 January 2019 (UTC)[reply]
Then the rodents presumably arrived by rafting. Robert McClenon (talk) 08:32, 5 January 2019 (UTC)[reply]
Robert McClenon, inside snakes being carried by bats between rafts during the Eocene (sometime before Europeons arrived) cygnis insignis 21:21, 5 January 2019 (UTC)[reply]
I haven't put in the effort to answer this properly, but for example Elapidae has members in and out of Australia. The genus also includes sea snakes, but I don't know how rapidly ancestral forms might have developed the ability to cross the ocean. This list of "ten deadly snakes" [16] are all venomous elapids; I haven't figure out, but if the continent was colonized by something akin to a sea snake I suppose it would explain why so many of its snakes are deadly. Wnt (talk) 15:07, 6 January 2019 (UTC)[reply]

Flightless Birds - Origin?

Now that we have discussed the arrival of snakes in Australia, I will ask about the arrival of the emu in Australia. There are large flightless birds known as ratite birds in Africa, South America, and Australia. Did the emu arrive in Australia by rafting, or by land bridge, or are the flightless birds paraphyletic, so that their ancestors flew, and they then evolved species that were too large to fly? Robert McClenon (talk) 23:44, 4 January 2019 (UTC)[reply]

January 5

Species identification

There's a picture I need to add a caption to, identifying the species in the pic. What kind of hummingbirds are these?

Please provide link(s). Thank you.    — The Transhumanist   01:33, 5 January 2019 (UTC)[reply]

Another one...

What kind of hummingbird is this?    — The Transhumanist   01:36, 5 January 2019 (UTC)[reply]

There could be three species in those photos. Abductive (reasoning) 01:45, 5 January 2019 (UTC)[reply]
For the first picture, of the two in New Mexico, I'm not sure we can see the birds clearly enough to identify them. I found a list of NM hummingbirds (with pictures) here. For the one on the left, all I can really make out for certain is the iridescent green on the back. There are multiple species in NM to have this, including the Broad-tailed hummingbird and Ruby-throated hummingbird (and probably others; please check through the list). According to that site, neither is very common in NM, though our article confirms that the broad-tail at least passes through while on migration. The picture was taken in May, though, which doesn't seem to be when they migrate. Sorry, maybe someone else can do better.
For the bird from San Fran, I think it's a Rufous hummingbird. Matt Deres (talk) 15:54, 5 January 2019 (UTC)[reply]
FYI, I've converted your images to thumbnails so they'd sit more easily on the page; I'm not sure why you'd set them as banners instead of thumbnails, but it was distracting. Matt Deres (talk) 19:07, 5 January 2019 (UTC)[reply]

Can organic chemistry reactions be calculated on a computer?

I've seen computer-generated videos showing what happens in some of these complex organic chemistry reactions, but can computers actually calculate what is happening? Computational chemistry doesn't say anything about organic chem. Bubba73 You talkin' to me? 08:39, 5 January 2019 (UTC)[reply]

3D-Visualisation of a Photosynthetic reaction centre (cytochrome subunit)
If you count PET/CT-Systems as computers, they can even be set up to track marked molecules in a body in realtime and that way track and measure biological processes in a living organism. Computers are also frequently used in fields like Process simulation or Chemical reaction engineering or simply as a 3D-Visualisation to understand more complex molecules or find key structures faster. Beyond that i doubt computers are successful in finding anything meaningful with purpose beyond their search pattern or to put it more precise realize when they find something special. --Kharon (talk) 16:44, 5 January 2019 (UTC)[reply]
I'm mainly asking about using physics to calculate how organic chemistry reactions work. Bubba73 You talkin' to me? 18:34, 5 January 2019 (UTC)[reply]
Like Folding@Home? Sagittarian Milky Way (talk) 19:35, 5 January 2019 (UTC)[reply]
Yes, I think that counts. Bubba73 You talkin' to me? 01:16, 6 January 2019 (UTC)[reply]
Tetrahydrocannabinol
Chemistry and especially Biochemistry or organic chemistry gets to complicated to fast and unpredictable if and how it interacts with other chemicals. Just compare the famous 2 drug Tetrahydrocannabinol THC and Cannabidiol CBD, which are a) almost identical and b)still very small molecules but they cause totally different effects in organisms and influence each others effects. A few years ago a study found CBD may be a Antidepressant[18].
If you could calculate even reactions of simple molecules, we would probably have drugs and medicine for every known illness and for future ones aswell today. Unfortunately we cant, not even with that very promising project Folding@Home that Sagittarian Milky Way thankfully linked. But nomatter its impressive 135 petaFLOPS calculation power apparently the best it manages to do is find "interesting Candidates" that have to be further evaluated by scientists for their potential.
So no. Computers cant calculate organic chemistry. Even with the power of a big commercial data center they need years to sort gazillions of possible combinations of molecules and their possible 3D structures for a "hey that one looks interresting". --Kharon (talk) 01:24, 6 January 2019 (UTC)[reply]
I'm not talking about calculating their effect, it is more about how the molecules operate on the molecular level, like DNA reproducing would be an example (probably one of the more complicated ones). Bubba73 You talkin' to me? 02:09, 6 January 2019 (UTC)[reply]
The level of sophistication I'm seeing here doesn't greatly impress me with its accuracy. But I don't know this area of research and I could be missing better efforts. Wnt (talk) 02:07, 6 January 2019 (UTC)[reply]

Astronomer vs. astrophysicist

It seems to me that more and more the general public is calling astronomers "astrophysicist". To name one, J. Allen Hynek - in the introduction he is listed as an astronomer but in the box to the right he is listed as an astrophysicist. He sounds like an astronomer to me. (I could name others.) Is this distinction getting blurred? Bubba73 You talkin' to me? 18:41, 5 January 2019 (UTC)[reply]

I think that in the twentieth and twenty-first centuries the distinction is probably one of self-identification by the scientist. Astronomy, by etymology, is the description of the stars. In early modern times it came to be the description of the telescopic observation of the planets and stars, first by Galileo and then by others. In the eighteenth and nineteenth centuries, after Newton showed that universal gravitation accounted for the orbital Kepler ellipses, astrophysics was the mathematical analysis of the orbits of the planets. In the twentieth and twenty-first centuries, astrophysics also includes the nuclear physics of what goes on inside the stars. Robert McClenon (talk) 20:04, 5 January 2019 (UTC)[reply]
In the case of amateurs, they are more likely to be called astronomers, especially if their research does not involve physics. They have long played a role of astronomy because of their willingness to spend time in observation. TFD (talk) 20:57, 5 January 2019 (UTC)[reply]
I had two astronomy teachers in college. One's research was in the interior of stars. I had him for celestial mechanics, and other things. Definitely an astrophysicist. The other's research was in observing galactic structure. He would be an astronomer in my mind. Bubba73 You talkin' to me? 21:32, 5 January 2019 (UTC)[reply]
I think that is the distinction people make, but it is becoming less distinct. As I remember, astronomy as the subject was called was part of the physics department and completion of the course fulfilled any requirements for high school physics. (That is if a course required prior completion of high school physics, then it was waived upon completion of an astronomy course. But there was also a separate "gee wiz" astronomy course that did not involve physics and did not count as a physics prerequisite.) TFD (talk) 01:21, 6 January 2019 (UTC)[reply]
Traditionally an astronomer was someone who named the stars -- observed what was in the sky. But now nobody reports that they "spotted a speck of light" at such and such a location; they have to try to explain what it is. And just explaining what it is involves things like Hubble's law and emission and absorption bands and if they are observing an orbital period and so on. So my feeling is that there is a lot of physics in any modern astronomy. Wnt (talk) 02:14, 6 January 2019 (UTC)[reply]

January 6

All-weather fighters

What was the first American or Nato fighter jet to have true all-weather capability (take off, intercept and destroy the target in any weather, and then land in any weather from an ILS coupled and/or manual approach and/or a PAR approach)? Is it true that the F-102 was capable of this? What was the first Soviet fighter jet to have the same capability? 2601:646:8A00:A0B3:74C8:E1A4:A5D:7436 (talk) 07:49, 6 January 2019 (UTC)[reply]

PAR approach is the correct wikilink. DroneB (talk) 11:04, 6 January 2019 (UTC)[reply]
It should be noted that "all weather" really means "most weather". The procurement specifications for "all weather" aircraft don't include the ability to fly into category 3, 4 or 5 hurricanes, severe icing, or H5 and larger hail. --Guy Macon (talk) 15:40, 6 January 2019 (UTC)[reply]
Also see: Lockheed WP-3D Orion. --Guy Macon (talk) 15:44, 6 January 2019 (UTC)[reply]
Indeed, it's more useful to consider the gradual improvement in aircraft capability. One useful metric is the percentage of operations that had to be scrubbed (cancelled) due to weather: you can compare how that percentage varied with time across aircraft types. Bear in mind that this analysis would be fraught with confounding variables, like the actual weather variability with time and geography of operations; and improvements to the infrastructure around the aircraft; and so on.
Personally, I consider the A-6 Intruder to be a significant milestone: its electronics and avionics look and feel very similar to modern aircraft. It even had computer screens in the flight deck!
Since the early days of aviation, pilots and engineers have been increasing the capability of the aircraft's control and navigation performance, marching toward operations in "all" weather. But even today, pilots use a healthy dose of Aeronautical Decision Making - that is, the scientific process of risk management (and specifically including quantitative analysis of the weather during the flight operation). If the sum total of all risks, including weather risks, exceeds a reasonable threshold, the flight must be scrubbed!
Nimur (talk) 17:35, 6 January 2019 (UTC)[reply]
And while we're digging into winter all-weather history, this was the front-page story on the All Hands digital edition during November/December last year: story about a now-famous F-9F flight - a specific mission launched in 1952 over a geographic region that today is either Korea, China, and/or Russia - the Navy pilots flew through a blizzard-condition snowstorm because their orders came from the cryptography division known in 2019 as the National Security Agency. When there's a reason to go, they can fly Panthers into snow...
This was an aircraft that was not "designed" for an all-weather role; its on-board systems and its pilot training regimen probably meant that it was not fully-prepared for combat operations in blizzard white-out. But, as long as you have a working compass, a working altimeter, and at least one additional instrument such as a turn coordinator, it is possible for a skilled pilot to keep their head up ... even though we'd all surely prefer an attitude indicator.
Nimur (talk) 17:50, 6 January 2019 (UTC)[reply]
The F-15 and F-16 both got an update to allow full allweather operation. I only read for the F-15 that the "F-15E" was the first version that was allweather but i guess the F-16 got updated at the same time. Likely it was mainly software since both fighters already had very capable, modern computers. --Kharon (talk) 18:38, 6 January 2019 (UTC)[reply]
General Dynamics F-16 Fighting Falcon says this: "it evolved into a successful all-weather multirole aircraft" (note piped link) and later this: "The first C/D version was the Block 25 with improved cockpit avionics and radar which added all-weather capability with beyond-visual-range (BVR) AIM-7 and AIM-120 air-air missiles." Martinevans123 (talk) 18:48, 6 January 2019 (UTC)[reply]
Thanks Martinevans123. I also just read the F-16 was the first manufactured with an advanced Fly-by-wire-System. Quite a package if you compare all that in the F-16C/D for ~19 million $ compared to the new fighters which are somewhere beyond 100 million $ a piece. --Kharon (talk) 19:28, 6 January 2019 (UTC)[reply]
It's a widely-known fallacy to compare costs on a unit-basis for such extraordinarily large Government acquisitions that span multiple decades. Consider reading Metrics to Compare Aircraft Operating and Support Costs in the Department of Defense, an extensively-researched economics policy whitepaper published by RAND and ... made available to the general public at zero-cost. Another relevant recent RAND Monograph, specifically as pertains to a total program cost comparison between F-16 and F-35, is MG-1225: Do Joint Fighter Programs Save Money? And if you're really following the news closely, here's RAND Report 2063 from July, advising whether a 24-month block-buy is a net cost savings between now and 2021; put simply, if we buy the same number of airplanes in 2021 and pay for them in 2021, they cost quite a different amount than if we pay for them in 2019, or if we pay for them in 2023; and if we decide in 2020 that we want to buy a different number of airplanes, the cost per airplane will also change! As you can surmise, this whole cost-per-airplane stuff is pretty heavily scrutinized by lots of experts!
Economics - it's a real thing with implications!
Of course, if you don't believe me, you can always hop on to Trade-a-Plane.com, where you, the discerning airplane-cost-expert, may purchase jets for discount prices, as long as you disregard the hidden costs of acquisition, transport, operation, training, airworthiness, maintenance, storage, fleet management, legal and regulatory items, taxes, tariffs, ... you know, the small details. I understand that as of January 2019, they even have MiG-29 listed on behalf of the owner.
Nimur (talk) 19:52, 6 January 2019 (UTC)[reply]
  • Some time before the F-102. Either the Gloster Meteor NF.11 (UK), the F-94 Starfire (US) or the CF-100 (Canadian). All of these first-gen jet fighters were of fairly limited performance compared to what came only a few years later, but they had the basics. and were really just intended as stop gaps before the Gloster Javelin, F-102 or CF-105 became available.
At this early time, there was little distinction between 'all-weather' and 'night fighter'. Both involved deploying on-board radar. The airframes were largely interchangeable, even if deployed aircraft might be long-term tasked to either one or the other.
The 'basics' here were to have radar, a second seat (as these early sets needed an operator who wasn't busy piloting) and two engines. This was mostly to lift the weight of a heavier radar-equipped, twin-seater aircraft with large fuel capacity (adequate endurance in the days before in-flight refuelling) – engines of this era were low thrust, so two were needed. A second engine was also needed for reliability in the real all-weather case. The F-94 was sngle-engined, but also had a lighter weight radar set than the others, of limited range. It used this radar for interception and gunnery, but search and acquisition was performed by ground radar (and the SAGE system).
ILS was still in its infancy at this time but was developing both rapidly and in gradual stages. It didn't 'suddenly appear' in one go. Andy Dingley (talk) 20:31, 6 January 2019 (UTC)[reply]
"All-weather" fighters was an outgrowth of night fighters. The Germans worked on night/all-weather version of their Me262, but since the OP ask about US and NATO jet aircrafts;
All of the above was capable of taking off, navigating, conducting combat and return to base (and land) in darkness and inclement weather. WegianWarrior (talk) 20:36, 6 January 2019 (UTC)[reply]
@Nimur So the F-16 from 1998 was US$18.8 million and the F-35B from 2018 is US$115.5 million. That is a 600% rise in just 20 years or a bit under 30% inflation per year. I dont need a lesson in economy and even less some made up science paper or study to see something went wrong there. Besides i remember even Mr. Trump had some talks about that with Lockheed Martin. Btw. the russian Sukhoi Su-57 aka T-50 will be US$50 million according our articles. Bet it has all the latest technology an F-35 has, so new technology is not the factor for these crazy (600%) developements, not is time. --Kharon (talk) 21:16, 6 January 2019 (UTC)[reply]
@Kharon: I wasn't following the whole discussion, but your math doesn't take into account that inflation per year is multiplicative (like compound interest). You want 6.00^(1/20) = 1.0937, or 9.4% increase per year. Of course, this doesn't change the total amount the price has increased! Wnt (talk) 00:06, 7 January 2019 (UTC)[reply]

Why are carbonate esters so obscure?

Carbonate esters have been promoted as "green solvents" (dimethyl carbonate), but aren't something I've heard much about. Probably this reflects a very limited role in biology, hence few sources of cheap bulk carbonate ester compounds -- even though there should be a carbonate analog for almost every ketone. I know that carbonic acid and bicarbonate are everywhere in the body, and I see a report about a catalytic antibody able to catalyze a relevant reaction [19] and apparently their stability isn't all that different from esters [20]. Artificially, people make polycarbonate plastics out of them. But I really see very little about them in the biological literature! What is the big obstacle that prevents biology from making free use of them? Wnt (talk) 18:42, 6 January 2019 (UTC)[reply]

Source of medical opioids like Percocet, Percodan, and OxyContin.

Could the pill manufacturers rely absolutely on synthetic production means, or do they have to use the poppy (the plant) proper for producing their medicines? --Doroletho (talk) 23:54, 6 January 2019 (UTC)[reply]

According to [21] "Synthetic opioids may be sub-divided into five chemical classes: phenanthrenes (including levorphanol and butorphanol), benzomorphans (including pentazocine and loperamide), phenylpiperidines (including fentanyl and its derivatives), diphenylheptanes (including methadone), phenylpropyl amines (including tramadol, tapentadol)." Those are fully synthetic; the others are either natural, or (mostly) semi-synthetic (natural materials that are chemically modified, like modifying morphine with acetic anhydride). Most of the semi-synthetic opioids still have a phenanthrene chemical structure.
I imagine that reference probably missed some more obscure classes from current research - it seems like somebody comes out of the woodwork with some yet more potent opium analog all the time nowadays. There are also cases like kratom where the classification is up for debate, and that too might be the case for obscure research chemicals. Wnt (talk) 02:09, 7 January 2019 (UTC)[reply]

January 7

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