Some high-Isp experiments

ToughSF posted a few avenues of research, early last weekend. Both definitively drawing-board. I'd have said something but I couldn't click the link to one of the actual papers then, so - you get my take on them, today.

One is laser-hits on a liquid propellant. It splashes. As far as ToughSF knows, nobody's solved this one. Then he went on to note how lasers sploot droplets. Next!

The University of Surrey is asking about magnesium rockets. I'd heard of burning aluminium (as Surrey spell it) in oxygen, or maybe some even stronger oxidant like ozone. Burning metals isn't for Earth or LEO, but it intrigues me for low-grav takeoffs like our Moon - once bermed. Magnesium is just as common over there. But again, this looks rife with Unsolved Problems. The link will be here (pdf).

Absent a pdf, we do get an illustration. It looks like AI and makes little sense to my mortal eyesight. I just see magnesium is not planned for surface-to-orbit roggets the way some were talking aluminum. They want mass drivers, to take this fuel into orbit which rockets burn it up there. Into that topic, PlanetaryEngSys has butted: that mass drivers should start small, such that the capsule then fire the engines on that (parabolic) trajectory, to bring it to orbit. Seems more reasonable than Surrey's proposal frankly. ESA should pay that grant to them.

Quirinius

This blog has had some occasion to look into The Third Gospel's use of material and into its general tendency. Some of Luke's changes can be illustrated with textual-strain. Among the more-diverting results is Jesus' long gestation: he was conceived in Herod's reign (d. 4 BC) as in Matthew, but he came out among us during Quirinius' census (r. AD 6). Mary bore a burden quite unlike those of most women.

Miracles, or snark, aside: at least Joslin McDowell never entertained that notion, Protestant as he is (yeah, he's still alive). He prefers that Quirinius was there several years before. And maybe this Roman was; but he wasn't doing census in someone else's kingdom. Especially not Herod's.

Michael Kochenash explains Luke's plan. Luke knew of Roman-Jewish talk that the census was a flashpoint of rebellion, and this rebellion in particular. Kochenash goes further: he notes Josephus (a Galilean friend of Herod Agrippa II) in The Jewish War and Antiquities. The former, Josephus completed before the Campanian volcano buried Agrippa's sister; this eruption received note only in the latter.

TJW is well aware of Quirinius' census and of the revolts around it. But this book does not connect those events with the Revolt. The connexion becomes explicit only in JA. Kochenash does not see Josephus, here, arguing that point for or against other historians like Justus. It seems an idea that Josephus had just... come up with. A reasonable idea, to my mind anyway; but never mind that.

Kochenash does not think that Saint Luke had come up with that idea, either, by himself. Instead - Kochenash argues - Luke made of it a trope. Roma and Judaea came into serious Imperial contact through that census. Luke associates this contact with Jesus' infancy. What the Jews do to Jesus, is going to post a milestone to the Ninth Of Av; which the Jews perhaps could have averted, by embracing him as Christ.

Crossan would supplement, here, the Holy Spirit as Divine gloría. This has abandoned the Jews to settle upon the Apostles, and - finally - upon Peter and Paul who are headed westward.

Capstone of prophecy

Adrien de Jarmy seeks to make a wave in sira studies. Namely to separate "Constitution of the Madina" therefrom.

He points out that the Constitution hails Muhammad by titles taken from sura 7 and derived from sura 25. The document also delivers taṣliya, as the Dome of the Rock upon Muhammad - and upon [sura 3-4's] Jesus. One title, "sayyid of the mursalîn", is not on the Dome at all. That title, to boost the Arab Prophet over that other Semitic prophet, would be a development from 70s/690s Umayyad thought.

That tracks closer with the sura 33+48 complex, that Muhammad is the "seal". De Jarmy posits that it is overall 'Abbâsid. Huh.

According to Crone-Hinds' God's Caliph, the Umayyads were shifting to the ideology that the Caliphate was the postProphetic dispensation. For this, they could use sura 48. Just about any 'Abbâsite propagandum about how Muslims need to come together and avoid fitna can also be found in Umayyad sermons and poems; which Crone and Hinds did so find. The only real distinction is that 'Abbâsids (later!) came to interpret their caliphate as the stand-ins for the Prophet rather than, as earlier, shadows of God.

Overall I'd like to see comparisons of the Constitution with the treaty-literature. De Jarmy can make of that, his next project.

CI origins

B type Bennu, like Cb Ryugu, corresponds to CI meteors sent down here from Above - like local CM, CO and maybe CT.

Now Maria Schönbächler et al. have formally published this, as reported in Switzerland Wednesday.

When the CIs accreted, they accreted with water ice. That "when", for Ryugu and arguably for Bennu, could have been as early as 2My after CAI formation. They take those "calcium-aluminum-rich inclusion" chondrites to be the eldest of them all, I assume marking that 4.567Gy age we keep seeing. Our CI, and I assume CY also, would precede CM and CO (and CV). By this time, Jupiter had grown to 20 Earth masses.

The paper accepts that Bennu is rubble from a parent. But, without naming 142 Polana. Polana presently rolls around 2.4 AU. This is well within the 4-5 AU ice line today, and assuredly in CM times then, therefore has migrated. The paper's "figure 5" speaks of something called "ureilites" to be native down at ~2.5 AU, sooty achondrite rocks from some differentiated parent destroyed 5 My after CAI beyond Vesta.

Such chaos may account for why the authors seem cautious about assigning general CI/CY (for asteroids, B/Cb) distance from our (very) young sun at this time. And they don't speculate on the Grand Tack; this may be because they must admit hazy understanding of asteroids beyond Jupiter. CI was once mooted as far as 7 AU, assumed for instance here (slushball Ceres remains, I think, a migrate from up there). Other papers have put CO out 3.7 AU so, hey, why not for CI.

Redshifts

This blog has typically left the vagaries of the Big Bang and its cosmologic models to better bloggers. Lately we have a few hits on this topic, so I've decided to annotate them.

Key to deep cosmology is deep time. The universe expands, which by Doppler is colouring the further galaxies to the red. So the unit of time is like the unit of Marine Isotope Stages: the higher the number, here z_sys, the deeper. By the way using z means we can leave aside the vexatious Hubble Tension, as to compare stratum to stratum.

The Turtle is pointing to cosmic daybreak, a term connoting more abruptness than "dawn". At z≤15.1, we have stars and galaxies; hydrogen and helium stars, anyway. Never before/greater-than. Pace Zim.

Three galaxies, where we can better see them, are already forming "metals" at z=7.2883, 7.8 and even 9.31. There is a reïonism event between 8 and 7, ending 5.3, which, I take it, had been obscuring our sight of higher z's. (Damned if I'm going to use the -isation suffix like some Star Control 3 alien.)

At z=7.76, estimated 660My from the start, comes a Black Hole Sun. So that isn't at the cosmic daybreak, pace the title; it's older than the 7.29 galaxy but younger than the other two.

I think these ancient red dots could provide furnaces fit to meld all manner of heavier elements. They point to the creation of early black holes generally. Neutron stars, I'll grant, might take a mite longer to form.

From the swamps to the hills

The consensus has been that teosinte was cultivated along the Balsas about 7000 BC. Then it has gotten vague, until that backwash from the Chibcha 3600 BC. Keith Prufer et al. are delving deeper into the spread of Mesoamerican maize.

I assume Mixe-Zoque for these first farmers.

Agriculture in Mesoamerica, they say, started with squash 8000 BC. Teosinte spread from the Balsas to Panama after 6200 BC and crossed the Darien a millennium later. (That Road To The South was always nasty for us.) At the same (belated) time it reached the Peten, which the paper calls "the Maya lowlands" although I question how Maya the place then was. After 3600 BC some intrepid northern highlanders crossed the now-yummy maize corn with some hardier altiplano breeds, making something that upland peoples (Otomí?) could live off of. This trickled back to southern Mesoamerica where, I understand, were other (relative) highlands as could now farm it. This breed got to South America too.

Except that even the post-Chibchan "Maya" stuck to lowland near-marsh farming of this crop. It took until the second millennium BC before they dared the hills. Overall the impression I get is that wetlands when farmed became non-wetlands, which then had to worry about changes in rainfall. This reminds me of how the lower Iraq suffered from droughts. And indeed the 2100s BC seem drier here as there.

I don't read where the American marshes got salted in Prufer's paper. I just read that they dried out. That was less a worry in the hills which, even if they don't rain, can catch ocean breezes and fogs overnight. The hills instead worry about keeping their soil at all. Indeed, after 900ish BC, I detect terracing: to actively manage erosion through slope stabilization.

Arabe 6982

This blog has had occasion to discuss how the Malikite branch of Islam brought their Qurʾāns with them, to Spain and to Sicily. Mostly these were of Nāfiʿ d. 169/785, through the intermediary Warsh. Other codices existed, such as that of Ibn ʿĀmir. The Umayyads preferred that one; some of the earliest (canon) Qurʾāns preserve it, when/where the Umayyads yet ruled. Malik (d. mid 790s) compiled his jurisprudence in a post-Umayyad age, when Ibn ʿĀmir too was on the outs.

I am elsewhere instructed that the ʿAbbāsids were - then - settling upon Abū ʿAmr d. ~152/770. So why not Nāfiʿ, eh.

Marijn van Putten is looking at BnF Arabe 6982. This, in the process of utterly trashing a work by Ala Vahidnia (who, and whose publisher, better be more careful in future).

We agree MS 6982 isn't quite the Nāfiʿ codex as in standard publication. (Leave aside how it has come to us.) Given that Spain was an Umayyad stronghold before, later, going Maliki; mayyybe this MS is a witness to its Ibn ʿĀmir phase.

No! says van Putten, who has access to Dani's taysir (and to Corpus Coranicum, which Vahidnia should use in future). MS 6982 is indeed Nāfiʿ, but along a side branch. Mostly Qālūn. A couple of minor exceptions: one - yes - Warsh (and someone else) and one other someone-else. The script anyway looks ornamental unlike like most Umayyad work.

I don't know who's done any work on what heifer the parchment was pulled off of. They say the binding is of North African style and "recent". Qālūn remains in print in Tunisia and Algeria; Libya too when they can keep the power on. For MS 6982 I can report that a terrible job was done, as the leaves are pretty-much random here. Q. 4:54-19:83, so already so curtailed when the binder got it.

I don't know that our MS ever breathed the Spanish air. At a guess it was commissioned in Kairawan or even Tunis, as Malik's disciples (like Ibn Wahb) were spreading their madhhab and their texts westward circa 185/800. Then brought to wherever-it-was before Warsh had quite nailed down the Nāfiʿ tradition over there. And then botched, I must assume by a Frenchman.