Wikipedia:Reference desk/Archives/Science/2018 October 10

= October 10 =

Could elephants be smarter than humans?
If they were smarter, I don’t see a clear way for them to act that would indicate ite fact, since they have mainly just their trunks and tusks to manipulate objects. Are there observations that imply they are less intelligent than humans? — Preceding unsigned comment added by Lassen Listening (talk • contribs) 02:24, 10 October 2018 (UTC)
 * Define "smarter" and "intelligent". ←Baseball Bugs What's up, Doc? carrots→ 03:07, 10 October 2018 (UTC)


 * Our article Elephant cognition is pretty good and has over 80 references. Cullen328  Let's discuss it  03:15, 10 October 2018 (UTC)


 * (e/c) I'm reminded of a quote from The Hitchhiker's Guide to the Galaxy, "For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much—the wheel, New York, wars and so on—whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man—for precisely the same reasons." We humans essentially define intelligence as being "like us", so it's hardly surprising that no other animals ever meet that standard. It's fairly clear that humans have a far greater capacity for abstract thinking, communication, and environmental manipulation than any other species. We kind of define intelligence as being able to do those things. If dolphins - or elephants - are capable of conscious thought, they probably define intelligence as being dolphin-like (or elephant-like, as the case may be). Less philosophically, elephants seem to have issues with even passing the mirror-test, though it's clear some can. See elephant cognition and the many many links therein, for a great deal more information. Matt Deres (talk) 03:23, 10 October 2018 (UTC)
 * You could also change the question a bit: Could a elephant "outsmart" a human? For example notice and avoid a trap you set or calculate like a hunter where to best confront you and then "get you" if it thinks you are a problem that can and should be "solved very easily". In that way some animals may turn out to actually be much smarter than humans in some situations! --Kharon (talk) 14:20, 10 October 2018 (UTC)

Potassium nitrate and nitrosamin formation
Can potassium nitrate lead to nitrosamines formation when in the stomach or at high temperatures? — Preceding unsigned comment added by AnonymousJohn25 (talk • contribs) 04:50, 10 October 2018 (UTC)


 * Dietary nitrate can spontaneously convert to nitrite, which can spontaneously form nitrosamines, so I don't see why not. But I don't see any references calling out that specific sequence. Someguy1221 (talk) 00:50, 12 October 2018 (UTC)

where is Fram Crater
Hi, I have been trying to find the coordinates of Fram Crater and it seems I cannot find it at all on the IAU Gazetteer of Planetary Nomenclature. Is it not an official crater? I found many references on the NASA website but not coordinates. Thanks --Golan&#39;s mom (talk) 06:14, 10 October 2018 (UTC)


 * Our article is at Fram_(crater). As you say, it's definitely not on the IAU list, so presumably unofficial. HenryFlower 14:22, 10 October 2018 (UTC)
 * 1.9°S 5.5°W - according to our article List of craters on Mars. It may not be listed as it is very small (8 metres in diameter) so is only known from images taken by the Opportunity rover - it may not be visible on images taken from orbiting satellites. Wymspen (talk) 14:27, 10 October 2018 (UTC)


 * Fram Crater is not presently in the database at NASA JPL's MarsTrek. The only reputable source cited by our article is this JPL PhotoJournal website, where "Fram Crater" is described in "scare quotes."  However, I went looking for other reliable sources and found the Science Magazine Special Issue (Vol. 306, Issue 5702, December 2004): Opportunity at Meridiani Planum.  This issue mentions Fram Crater in multiple papers:
 * Mineralogy at Meridiani Planum from the Mini-TES Experiment on the Opportunity Rover (Science, 2004)
 * Soils of Eagle Crater and Meridiani Planum at the Opportunity Rover Landing Site (Science, 2004)
 * ...and the penultimate paper for you, our reader-with-interest-in-interplanetary-localization:
 * Localization and Physical Property Experiments Conducted by Opportunity at Meridiani Planum (Science, 2004)
 * There is a lot of very difficult theory and practice that pertain to describing a location on another planet - especially when we start talking about putting landers and rovers on said planet with the intention of driving to features of interest - so that last paper is the one you should read first.
 * Additionally, the 2006 issue of IEEE Robotics included a paper from the JPL navigation experts: Jeff Biesedecki et al.: Mars exploration rover surface operations: driving opportunity at Meridiani Planum (IEEE Robotics & Automation, 2006), in which the authors take credit for informally naming the Fram Crater.  They also present lots of fun technical details about why nobody knows where this crater really is:
 * "With considerable slip and time constraints preventing use of visodom, we knew the rover's internal position estimate would not be very accurate. Not making use of the internal position estimate precluded the use of Go_To_Waypoint and Turn_To commands, conditional sequencing based on estimated distance to a Cartesian location, and even remote sensing commands designed to image specific X, Y, Z coordinates. Instead, our mobility sequences were almost all geared to using combinations of Turn_Absolute and Arc commands based on predictions of what our slip would likely be."
 * ..."Drives along the rim were all done with Arc and Turn_Absolute commands. We were driving on generally rocky berm, on a slope that was away from the crater interior (so slip would take us away from the rim itself, which we liked). The drives were kept short enough that we had a clear view of our drive path and could verify it was clear of obstacles and ejecta. We avoided doing sharp “dog legs” because we were driving far enough that stereo range data was not precise, and we did not trust the precision of our localization in the orbital maps. So most days were straight drive segments, approximately 40 m/sol."
 * I have added links to these references to our article.
 * So - the location of the landing site is known to better than 10 meters accuracy; the location of certain other crater features visible from orbit can be known with excellent precision - but the positions for many of the features that Mars Exploration Rover Opportunity actually visited and photographed are not accurately known. We can safely say that Fram Crater is a few days drive - perhaps a couple hundred meters - from the nearest big rock, informally called "Bounce Rock" - but otherwise at unknown distance and bearing, on the featureless terrain of the plains of the Meridiani.
 * Nimur (talk) 17:31, 10 October 2018 (UTC)
 * Other sources which discuss the crater, although probably don't help with the localisation, that I came across earlier are [//agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2005JE002465 Crater gradation in Gusev crater and Meridiani Planum, Mars] and [//agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2006JE002776 Opportunity rover localization and topographic mapping at the landing site of Meridiani Planum, Mars]. BTW this source [//mars.nasa.gov/mer/spotlight/spirit/a24_20040602.html] which I added to the article discusses how these unofficial names for the crater came about. The unofficial names don't comply with the IAU naming rules, so I don't think they were intended to be possible official names. Nil Einne (talk) 18:25, 10 October 2018 (UTC)

Does the hypothetical compound XeH2 have a dipole moment?
This was one of the last questions on a recent general chemistry I exam at Columbia University. I'm a tutor and my student was thrown off by this question.

Firstly based on MO theory this bond arrangement would be very weird. The most stable bonding arrangement would involve Xenon exciting a single electron from each of two nonbonding orbitals to two new higher energy orbitals to form a bond with H•. However this bond is much weaker than the H-H bond and would decompose almost immediately. I don't think this is a fair question, but I also anticipate seeing bent geometry. Should my student appeal this question? Yanping Nora Soong (talk) 18:38, 10 October 2018 (UTC)

I think my student's professor may have merely wanted her to have memorized XeF2. in XeF2, xenon is able to use its "expanded octet"(having ten valence electrons) because F lowers the energy of the resulting molecular orbital involving dsp3-sp2 atomic orbitals from Xe and F respectively. H cannot do this. It simply isn't electronegative enough.

to me, concepts should supersede using the mere memorization of facts to extend a motif to a molecule that doesnt exist. Yanping Nora Soong (talk) 19:03, 10 October 2018 (UTC)
 * Calculated properties of XeH2 (abstract). DroneB (talk) 20:09, 10 October 2018 (UTC)


 * "Hypothetical compound", therefore there is no grounds to appeal based on whether it would be even slightly stable. Based on DroneB's nice ref, you now have deeper information about the concepts, and see if your understanding of what "cannot" happen is on target, and how widely applicable the XeF2 pattern is. The only ref to this compound on en.wp is in polyhydride, which cites 10.1063/1.4931931 for several XeHn. I cannot access the fulltext at the moment:( DMacks (talk) 21:30, 10 October 2018 (UTC)


 * Hypothetically this is stable from 1 to 200 GPa. XeH2 in this state is solid in orthorhombic crystal form, space group Cmcm and so is symmetric with no dipole. Graeme Bartlett (talk) 09:16, 13 October 2018 (UTC)


 * If you're just supposed to be learning entry level VSEPR theory, without getting into the higher-level bonding theories like MO, then the Lewis diagram would have 5 electron domains around the central Xenon, which would give a trigonal bipyramid electron arrangement; and in that arrangement, maximal electron pair repulsion would put the three lone pairs in the equatorial position, and the two H-Xe single bonds in the axial position. The H-Xe-H bonding angle would be 180 degrees, which would have no dipole moment.  Which is one way to approach the problem.  I would ask the professor which particular principle, theory, or idea the problem is supposed to be allowing you to explore; the answer you give to a problem like this depends entirely on which ideas you are supposed to be applying.  -- Jayron 32 22:32, 10 October 2018 (UTC)


 * I'm teaching an "atoms first" paradigm -- where my student uses approximations like pedagogical effective nuclear charge from the very beginning to get an intuition for the energy of orbitals and why hypervalent bonding occurs. The common VSEPR bonding structures naturally arise from these considerations. I'm frustrated by questions which have students have to discard common sense chemistry concepts, because they have to use these concepts for organic chemistry. Yanping Nora Soong (talk) 00:06, 15 October 2018 (UTC)


 * I justify my student the existence of XeF2 by using a very simplified Lewis model discussion of the three-center four-electron bond. I dislike having my students memorizing stuff they have to unlearn later that really messes them up in organic chemistry, and my teaching paradigm is that undergraduate introductory organic chemistry is "90% concepts 10% memorization". This Lewis model helps them also learn or reinforce Lewis acidity/basicity, resonance and the HOMO/LUMO interactions which will be used extensively later. Having the student extend XeF2 to XeH2 meaninglessly does none of that. However, my student did not wish to "cause a ruckus" and decided not to appeal. Yanping Nora Soong (talk) 00:15, 15 October 2018 (UTC)
 * All of that may be true, but you're missing the point here. Pedagogy is not merely the listing of true things that students are supposed to magically understand simply because you told it to them.  Pedagogy requires knowing how to build up knowledge in students through a series of approximations and simplifications so that students can be intellectually prepared to get more and more accurate views of the world.  I do agree that in general one should avoid blatantly incorrect examples when teaching simplified models, but it isn't really the end of the world here.  The theoretical basis for this sort of "building up" of knowledge in the learner probably dates to psychologist Lev Vygotsky (see Zone of proximal development) and more fully developed as the practice of Instructional scaffolding.  See also Wittgenstein's ladder, which is sometimes derisively referred to as the lie-to-children, but really is a valid instructional practice.  In simple terms, you don't start with general relativity when teaching new learners about simple motion.  You start with classical mechanics and build them up to it, even though you as a physicist know that the Newtonian equations of gravitation are incorrect, you don't drop the Einstein field equations on them on day one of the lesson.  Similarly, introducing advanced models of molecular bonding theories on a student without them having a solid basis in the simpler models isn't necessarily beneficial here.  Again, in order to know how to help your student solve their problem with determining the polarity of the putative XeH2 molecule, it is important to know why did the professor give the XeH2 problem to begin with that is what principle is the professor trying to teach through the use of that example. It really isn't important if the example is even correct (again, it is a Wittgenstein's ladder), merely that it can be used to demonstrate a specific concept.  Perhaps the XeH2 problem was intended to allow the student to explore the ideas you are bringing up, but unless we know that, we can't know how the student is to approach the problem.  If you lead them down that route, you could be leading them into topics they aren't going to be able to incorporate into their own knowledge base because they have not been properly primed for them by learning simpler concepts.  -- Jayron 32 12:44, 16 October 2018 (UTC)

Gallium and miscibility with other metals
Is gallium miscible with mercury, sodium, lithium, potassium and NaK? Are these alloys liquid around room temperature? Thanks!--82.137.12.135 (talk) 23:46, 10 October 2018 (UTC) posted by request from my talk page -- Jayron 32 23:55, 10 October 2018 (UTC)
 * The large electronegativity difference between gallium (1.8) and the alkali metals sodium (0.9), potassium (0.8) and lithium (1.0) makes it unlikely that they will form metallic bonds. Looking at a Ketelaar triangle, such bonds would fall in the Zintl range. I would expect gallium to dissolve in liquid mercury, but I can't find any references relating to it. Handschuh-talk to me 01:15, 11 October 2018 (UTC)
 * This article contains some examples of gallium-alkali metal zintl phases. Handschuh-talk to me 01:38, 11 October 2018 (UTC)


 * This NBS report covers attempted alloying of gallium with various metals with the specific aim of finding new dental-filling materials. DMacks (talk) 02:40, 11 October 2018 (UTC)
 * Mercury + gallium non-alloying (if you trust YouTube). DMacks (talk) 02:48, 11 October 2018 (UTC)


 * Thought i have seen it mentioned in newer battery/anode technology, which is a huge, extremely active research field since fossil fuels became troublesome. The percentages for the Gallium part where actually extremely low however. --Kharon (talk) 13:43, 11 October 2018 (UTC)


 * Thanks for that video - that's a fun one! I've long wondered how many simultaneous immiscible liquid phases you could have in a container if you really tried, and this adds one more.  More to the point... can you make a separatory funnel with mercury and gallium and use it to purify and separate metals?  Can you categorize metals as "mercurophilic" or "gallophilic"??  (I looked ... but "mercurophilic" seems to mean some other obscure thing that affects bond distances in a molecule) Wnt (talk) 10:23, 12 October 2018 (UTC)
 * The elements' tendency to prefer dissolution in one fluid medium over another is usually categorized using the Goldschmidt classification. According to this system, both mercury and gallium are chalcophiles, which again, would point towards them being miscible, though obviously isn't definitive. Handschuh-talk to me 01:55, 13 October 2018 (UTC)
 * That reminds me of The Beach (film) where the two boys utterly failed to consider resolving their sexual rivalry amongst themselves. Not all that love oxygen love one another. Wnt (talk) 16:33, 13 October 2018 (UTC)