Wikipedia:Reference desk/Archives/Science/2024 May 29

= May 29 =

Elderly digestion
Older people have more distended intestines due to loss of muscle tone. It also means food is pushed along more slowly along the digestive tract. Does this mean that per ounce of ingested food, elderly people will extract more nutrients?

Of course, if this causes them to eat less, it may not mean more calories absorbed. Imagine Reason (talk) 09:24, 29 May 2024 (UTC)
 * I don't know if any of the premises of your argument are correct. But consider this; for about half a billion years our ancestors have had a digestive system. Extracting every usable bit of nutrients from our food has been under strong selection the whole time, because starvation kills and food is limited. Why then would a malfunctioning elderly system do better? Abductive  (reasoning) 18:54, 29 May 2024 (UTC)
 * There is an evolutionary pressure to extract every usable bit of nutrients from our food. There's also an evolutionary pressure to keep the power-to-weight ratio of the digestive system high. Wasting some nutrients to keep the digestive system light may be benificial. I'm not suggesting I disagree with your conclusion. PiusImpavidus (talk) 19:54, 29 May 2024 (UTC)
 * The human digestive system is far from perfect in extracting calories. Imagine Reason (talk) 21:52, 31 May 2024 (UTC)

Elvish astronomy
Considering Legolas' canonical feats, what would be his naked-eye limiting magnitude, assuming seeing conditions in which the average human would get 6.0?

(The main reason for this question is that in Morgoth's Ring an Elvish name for Neptune is given. Though I suppose they might've been using palantíri as telescopes.) Double sharp (talk) 09:36, 29 May 2024 (UTC)


 * Perhaps elves have eagle eyes; Tolkein is silent on the issue. Alansplodge (talk) 11:15, 29 May 2024 (UTC)
 * He does kind of imply at least that the naked-eye limiting magnitude is greater for Elves than for Men. In The Nature of Middle-Earth, "Dark and Light" it is written: The Quendian imagination of the shape of Arda and of the visible Heaven (Menel) above it, was due to the acute minds of a people endowed with sight far keener than the human norm. Though this is for the Round World version, in which the Sun and Moon already exist from the beginning. As for quantitative figures, I guess we're stuck with the data point of Legolas counting 105 horsemen from a distance of 24 km.
 * Actually, it occurs to me that (perhaps more interestingly than limiting magnitudes), Elves really ought to be able to resolve the Galilean moons of Jupiter. This provides an alternate solution to the longitude problem, at least if you take the Round World versions. :) Double sharp (talk) 15:20, 29 May 2024 (UTC)
 * The Galilean moons would be a cinch for an elf. I had a (human) friend who could do this (he was tested on it several times). Not being particularly interested in astronomy, he only found out in his adult years that this was not usual for most people. {The poster formerly known as 87.81.230.195} 94.2.67.173 (talk) 19:42, 29 May 2024 (UTC)
 * Hmm, probably also the crescent of Venus should be resolvable for them. This perhaps has implications on the shapes of the Silmarils. (Although in the Round World Version, Venus already exists beforehand, and its identification with Eärendil is said to be mythologising. From the same essay I quoted: Certain stars (no doubt those we call planets) and among them especially Venus, which they called Elmō (and later mythologically Eärendil), they early observed were “wayward” and altered their places with regard to the “farstars” (fixed stars). These they called companions of the Sun and thought them quite small heavenly bodies – derived from the Sun.) Double sharp (talk) 02:31, 30 May 2024 (UTC)
 * The limiting magnitude can be increased with a sharper view. The sharper the view, the smaller the area of the detector (retina) on which the light falls. The background light is fixed per unit of surface area of the detector, so with the signal on a smaller area, less background competes in this area, increasing signal-to-noise. A sharper view can also help to take a faint object out of the glare of a nearby bright object; relevant to see the Galilean moons.
 * The other way to increase the limiting magnitude is by increasing sensitivity. No matter how sharp your eyes are, you need a couple of photons before you can see anything. The more photons you detect, the lower the relative Poisson noise. The sensitivity can be increased by (A) a better detector, detecting a larger fraction of the incoming photons; (B) larger aperture, i.e. a bigger pupil; (C) increasing integration time. Many nocturnal animals (and elves may be somewhat nocturnal) have better, more sensitive detectors, although at a price. The tapetum lucidum found in many animals reduces resolution somewhat; some species sacrificed colour vision for better low-light vision. Bigger eyes help to see better, but although Tolkien often writes that Elven eyes are keen and fair, he never writes (AFAIK) that they're big. Maybe elves can at will increase the integration time of their eyes. For humans it's fixed at several centiseconds, but if elves can boost it to a full second (they would largely loose the ability to detect motion), seeing Neptune shouldn't be too hard. Still takes a lot of dedication and patience to find out which of those tens of thousands of faint stars slowly moves, but patience is something you should have if you live forever. Ents might disagree. PiusImpavidus (talk) 20:55, 29 May 2024 (UTC)
 * Why would Ents disagree? They have loads of patience (though it is unclear if they are immortal or just extremely long-lived). Clarityfiend (talk) 22:23, 29 May 2024 (UTC)
 * Ents might disagree with the statement that elves have patience. PiusImpavidus (talk) 11:07, 30 May 2024 (UTC)
 * Thanks for the details! I guess I'm personally more inclined now towards explaining the Neptune thing by an Elvish invention of the telescope.
 * Or maybe the Valar told them where to look, noting that Neptune's magnitude is actually brighter than the most extreme reports of naked-eye viewing of stars. It would be a lot easier to find Neptune if you already know where it is, than to find which of those myriad faint stars is slowly moving. In NoME, Elvish Reincarnation implies that the Eldar were informed about isotopes by the Valar, so this isn't unreasonable in-universe. (Though finding that passage makes me amused by the thought of seeing Galadriel's NMR spectra.) Double sharp (talk) 04:23, 30 May 2024 (UTC)
 * In canon Men are sometimes mistaken for Elves, so there must not be any gross difference in eye size. —Tamfang (talk) 21:37, 30 May 2024 (UTC)
 * Assuming a comparable physiology, an Elven retina may pack more sensitive photoreceptor cells, while the lens may have better optical qualities. --Lambiam 06:08, 31 May 2024 (UTC)

I wouldn't take it for granted that the Solar System outside of Middle Earth is the same as the real one. According to The Silmarillion Earth (or "Arda") was explicitly created by God and smaller deities with their omnipotent powers, and so were the peoples of that world (Elves, Men, Dwarves, and surely Hobbits and Ents, too). And the part that would drive mad the astronomers reading that book, the Sun and the Moon were also created by those beings... ages after the creation of Arda, and after life existed on that world. Cambalachero (talk) 13:00, 31 May 2024 (UTC)
 * Indeed. But Tolkien planned in his later years to make an altered Round World Version in which the Sun and Moon exist from the beginning of Arda. In that case the Two Trees simply preserve their light as it was before they were tainted by Melkor. As I quoted above, these late rewrites imply that the planets in Tolkien's world are the same ones that we have. :) Double sharp (talk) 11:05, 1 June 2024 (UTC)
 * Hmm, curious where you heard about these supposed intended revisions to create a lore more consistent with actual astral bodies. I'm a little skeptical without seeing a source on this, just because it doesn't seem to add up with other well-established details.  Bear in mind that every element of the legendarium that bears light on the creation and cosmology of Eä was published after J.R.R. Tolkien's death.  Christopher Tolkien finished The Silmarillion by trying to faithfully patch together the content (and fill in gaps himself) using an express desire to have the final work reflect what his father, the original author, would have intended.  Nobody would have been in a better position than the younger Tolkien (who made the completion of the legendarium a substantial part of his own life's work and had the fullest access to the existing materials) to know what the elder intended in this respect, and he would have had every opportunity to cause the final work to reflect it, as he did with countless other details.   Further, thematically it just doesn't seem to fit: the trees are so fundamental to the cosmonogy of the legendarium, as well as its evolution and eschatology.  The trees are part of the more gnostically "pure" version of the world after it was sung into existence out of the higher pleroma by the music of Ainur.  The fall of the trees, though instigated by the machinations of Melkor and Ungoliant, are thematically (and arguably psuedo-naturally) the result of an inevitable and unarrestable trend of the world trending away from the direct influence of the Valar and towards a world more defined by physicality and all the ills that come with it.  All of this being the result of Melkor's discordant notes, which Eru permitted to remain a part of the song of creation.  First the Valar leave Middle Earth and retire to Valinor, and as time wears on, begin making less and less in the way of even indirect influence over it.  Next, the Trees are destroyed and the First Age begins.  Later the world is reshapped such that Valinor is not even entirely on the same physical plane as the rest of Arda, and reachable only via the Straight Path.  The elves diminish and go into the West, returning ultimately to Valinor, the magic and grace of their realms failing and converting them into mundane lands.  Meanwhile the light of the trees persists in the silmarils and the phial of Galadriel, bitter sweet echoes of a purer but irretrievable age. Magic fades and Illuvatar's second (and less ethereal) children, humans, inherit the world.  You see what I mean? The idea of the world's inclination to a state defined increasingly more by a base, more purely physical state and away from the direct influence of the spiritual animus that gave birth to it is baked into the narrative and the lore, from start to finish.  And the trees are the ultimate symbol of the starting point (or at least the start after the music was finished and the Ainur descended into Arda).  Besides, the sun and the moon predating the round world just doesn't make much sense: a flat Arda wouldn't be able to rotate on is axis.  Mind you, not to imply that there's in way to get the legendarium's cosmology to work with actual astrophyics.  Which Tolkien very well knew: all indications are that this was a part of the point.  But introducing the sun and the moon before the First Age just makes the discontinuities more obvious and intrusive.All that said, very curious to see where this comes from originally.  Certainly there is no shortage of matters that Tolkien went back and forth on over his decades of revisions of the relevant works, nor issues where his son had to make best-guess efforts in choosing among the disparate versions of events.  But personally, I tend to doubt that Tolkien seriously considered this particular shake-up.  Tonally and in terms of continuity, it just doesn't add up. -sighs a sigh of glutted satisfaction, having sucked out all of the fun the subject matter and wrecked it as surely as a giant spider sucking the magic out a world tree and poisoning it.- SnowRise let's rap 02:51, 3 June 2024 (UTC)
 * There is a good summary here, though the primary sources (JRRT's texts) are still in Morgoth's Ring (ed. Christopher Tolkien) and The Nature of Middle-earth (ed. Carl Hostetter). A scholarly paper about it is here.
 * A slightly shorter summary: pre-ROTK, JRRT produced a version of the Ainulindalë with the changes to the cosmology. Melkor seizes part of the Earth to make the Moon for his stronghold, before the Valar cast him out of it and cleanse it. For the time being, it was only an experiment.
 * But in the late 1950s, JRRT came to believe that the making of the Sun and Moon was too "astronomically absurd" to write in an age when most people believe that the Earth is spherical and is more or less like an island in space. So he came up with a new concept: the "Flat World Versions" are traditions that were handed down by the Númenoreans and then in Arnor and Gondor, that are inescapably blended and confused with Mannish myths. The Elves had their own lore from Valinor that was astronomically and geologically in accord with what we know instead.
 * JRRT describes the new cosmology across some essays published in the aforementioned collections and in an interview. The Sun and Moon were created together with the Earth, and originally they had the Primeval Light, and what Melkor did instead was corrupt them. Middle-earth was then twilit, because Morgoth darkened the Earth with clouds, such that the stars and moon were invisible and the Sun was only a dim twilight (something like the real Venus without the greenhouse effect, I might add). The significance of the Two Trees is that only there was the Primeval Light preserved, and Varda domed Valinor over to keep Morgoth's corruption out and have it only be lit by the stars. The world was also round from the beginning, but you could not circumnavigate it before the drowning of Númenor because Aman would block the way. The Númenorean Catastrophe removes the inhabitants of Aman from the physical world, though the landmass remains and becomes America after significant geographical upheaval. Thus JRRT writes in these notes Aman and Eressëa would be the memory of the Valar and Elves of the former land.
 * Crucially, in 1966 The Hobbit was slightly edited in accordance with this new revision: where once read In the Wide World the Wood-elves lingered in the twilight before the raising of the Sun and Moon (completely correct per the Flat World version), there now read In the Wide World the Wood-elves lingered in the twilight of our Sun and Moon. JRRT's late texts published and edited by Christopher in The Peoples of Middle-earth sometimes also imply this: the new description of Fëanor's burning of the ships specifies that it was done "in the night", and that "In the morning the host was mustered", which makes no sense in the old cosmology because the Sun wouldn't yet have first risen; and Thingol's throne room of Menelrond is supposed to be based on the domes of Varda (which don't exist before the changes). The heraldry JRRT drew in the 1960s for the House of Finwë is a "Winged Sun", which also makes more sense in the new cosmology because Finwë otherwise could not have seen a Sun that only rose after he died. So the evidence is clear that the elder Tolkien really seriously intended this change.
 * As for why it was not adopted by Christopher: Christopher's commentary on these texts indicates that he seems to have thought it a bad idea on the part of his father. I think Christopher made a sensible call, as going on with the intended changes would require much more editorial intervention than leaving things as they were: it does not seem that JRRT ever finished the planned rewrites. But from my perspective as a fan, the whole idea is fascinating and allows the amusing conceit of trying to figure out what was really going on behind the scenes, which is why I asked the initial question about how astronomically plausible the reworking was in one aspect (the visibility of Neptune). Double sharp (talk) 03:45, 3 June 2024 (UTC)
 * Fascinating! Just when I thought the paratextual narrative of this particular piece of literature couldn't get more complicated! Personally I like the ultimate approach adopted (even beyond the concern you rightly point out of it requiring more intervention--I still think I prefer the narrative irrespective of whether you hypothesize a scenario in which J.R.R. could make the adjustments himself). The Age of the Trees being treated as literal (or at least facially literal from the perspective of the Silmarillion/legendarium's narrative; all of the books are presented to varying degrees as possibly unreliable ancient historical text, after all) just feels very at home with both the broader cosmogony as well as the thematics of the overall work.  But then, I have revisited those books so many times over the years (at least compared to my once, maybe twice and done policy for most literature: soooo many things to read!) that I may have some bias! Sn<b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b><b style="color:#d4143a"> let's rap</b> 16:54, 3 June 2024 (UTC)
 * I kind of think of JRRT's problem as being that in seeking increased verisimilitude, he'd gone from wanting to write a mythology to wanting to write a science fiction novel. Only, instead of starting a new science fiction novel and leaving the mythology as it was in its almost-complete state, he ended up trying to turn his mythology into a science fiction novel, with predictable results. But I suppose the whole narrative was too dear to his heart for him to come up with another like it, just like the Silmarilli were to Fëanor. Which is understandable: I share your obsession, and how much greater must it have been for the author? :)
 * With that said: even in this take, the Age of the Trees would still be literal in the sense that there were luminescent trees in Valinor that got killed by a giant spider. They would only not be literal in the sense that the Sun would still be shining (in its form post-tainting by Melkor) over Middle-earth. Only in the northwest (over Beleriand) is there a volcanic winter due to the fumes of Thangorodrim – and from that, we can see where the idea of the Sun first rising later comes from as an in-universe myth. Double sharp (talk) 10:42, 4 June 2024 (UTC)

Rereading Dark and Light (late 1960s) strongly suggests to me that Tolkien was actually thinking about some of this in his last years! As I noted above, the phases of Venus should have been visible to the Elvish naked eye (noting that this is the Round World version, so Venus already exists as a planet), and that means that they could not ever have been Ptolemaic geocentrists! And thus in JRRT's text we find that [the primitive Elvish cosmology] was geocentric only as regards the Sun, Moon, and certain stars (“companions of the Sun” or wayward stars = our planets). Well, if the planets were seen as companions of the Sun, then this was a Tychonian system! Double sharp (talk) 07:04, 4 July 2024 (UTC)