Cooling the halo

This morn we posted Orion's answer to the Halo: the spinning wheel is supported by a nonspinning magnetic shell. Like a lobster is boiled in its own shell.

You see, the older, simpler, thicker shell can offer something Elliot Orion Ruzicka hasn't considered: heat exchange. The outer shell gets outfacing radiators pointing in any direction. But... if there's a vacuum between the habitat and the outer shell, how's the habitat getting its heat to the outer shell?

Perhaps the separative medium is an efficiently-conductive gas. Like hydrogen. Superheated hydrogen between our oxygen-infused habitat and the outer shell, which spin we maintain by some turbine in the hub of the spokes. Oh the humanity.

Nah. The outer shell has to be a half shell, reflective on the outside. The radiators are then attached to the inner shell orthogonal to the direction of spin, or maybe tilted slightly outward.

As they say, amateurs study engineering; professionals study thermodynamics.

Breaking diameters

Been a hot minute since I last dropped in on the ToughSF X account. Ten days ago it linked to a cycler plan - to which I may or may not get. Right now I'd like to discuss its own source, Elliott Orion Ruzicka's submission to the IAF's 75th congress 2024. In his capacity as head of "Orbital Design" in New York.

That's a "Mr.", not a "Dr.". Shows how much credentials matter for awesome material-science papers.

Ruzicka notes that the Halo doesn't work, much less the Ringworld. Since they both spin, each puts pressure on her outer wall. Maximum pressure happens to correlate with radius (or diameter, or circumference): F / gr. Humans like g=9.8 m/s². I'm willing to negotiate for Venereal 8.7 - but now we have to consider the tensile strength of the outer hull, and how thick that might be. The outer shell can't be allowed to dip much less than 9.8.

Given alla'that, cometh our list of tensile materials before this contraption flies apart. As usual Kevlar is in here, maxing out 0.513 mega-meters... 513 km across. As a post-1980 paper we can also use Zylon 759 km. Nanotubes and graphene also make their appearances but I consider them unobtania. Six years ago our boy ToughSF related the T1100G. This was density 1790 and max force 7000 MPa. That last looks rounded: I get 400 km radius = 800 km diameter.

Janhunen's dumbbell and Jensen's smaller stuff were keeping it to decakilostructures, fit for high Earth orbit where space is at a premium and we don't want to bombard our green home. The max-out hectakilostructures were more than enough and, who cared about muh nanotubes. Ruzicka, mad lad, wants a MEGA structure. He floats up to 102,040 km held by 100 m of graphene; compare Earth equatorial 12,756 km... or Saturn 120,536 km. Maybe keep this monster at Venus Equilateral.

But even if we're not demanding this absurd artificial subSaturn, Ruzicka can still save on construction-material to keep it together. A 10,204 km subEarth might need that 100 m now; this would go down to 9.09 m.

Ruzicka's magic is in installing a torus within a torus. The outer ring keeps the micrometeors out and does not spin. Only the inner ring rotates for the artificial gravity. The inner and outer rings are thereby decoupled. They just need to keep from mutually crashing into each other, which can be gently nudged by magnets.

Ruzicka proposes to spin it up in the first place, by - you guessed it - magnets (but stronger). This will require the outer ring to spin in the opposite direction, at first; but this can be mitigated either by using rocket-engines or, better, building two at a time to spin in opposite directions, which would cancel each other's twists.

THERMO 9:50 AM: A hot minute indeed.

The book of Psalm 108-110

We have a few articles by Christians asserting that the early Church read the Psalter - which is our Psalter - as a unity, a single book. Lately: SD Ellison (which I haven't read) and James Hamilton Jr (pdf - have read). Maybe Jon Alan Ginn. Let us ponder unity as unification.

The Greek translation is pretty-much just the MT here except enumerated with some offsets. Qumran has some differences to be discussed (soon!). Our main topic is the Psalms triplet 108-110 in MT, 107-109 in Greek. If deliberate, the editor presented Psalm 109 as a royal work alongside 108 and 110.

Most agree the edition of this last fifth of the Psalter dates well after the exile, adopting Psalm 137 among others. The collection's motive would be that of Messianism: the people didn't necessarily have a king in those days, so - they wanted one. Note that this is the fifth where Qumran rates the collection as fluid-enough that variant orders can be ventured, secondary or not; Qumran does not venture this for Psalms 1-88.

I stress this does not mean all these Psalms were composed for that editorial purpose. Psalm 137 didn't expect any king but God. We are, for now, discussing the edition, which allows for angry strays like Psalm 137 to exist along more-hopeful work.

Psalm 109 would then be such an angry stray. It reads like a curse tablet. The man is going before the court with a satan at his right v. 6, an accuser human or otherwise. Instead the man requests YHWH at his right v. 31. Thematically it leads well into Psalm 110.

Somebody moved to the Chincha valley

When the Huari ruled, they dealt with postMoche coastal peoples without much conquering them. Then around AD 1100 the Huari collapsed. We next find people harvesting guano... much further south, in the Chincha vale. AD 1250 is about when they start advertising their birdey wares on pots.

The link between the Chincha of their guano era, and their northern postMoche origins, now exists from genetics.

As to: why the migration. Uh. We have evidence for rather a lot of upheaval around that continent, from the 1200s (thirteenth century) on.

Once having migrated, the Chincha jealously maintained their culture, some even being endogamous. The language of that coast when the Inca came was Coastal Quechua; "Chincha" itself means "ocelot" in that language. The homeland of "Quechua I" also lies north of Cuzco; which highlands today speak an archaic dialect called Huanca (no jokes plz).

I suspect the Huanca and the majority Chincha both descend from the Huari, who spoke Quechua. The bird-doo-doo people, as coastal... I doubt. Their ancestors had spoken something more Mochean-era in northern Peru, if not Mochic itself; further, I expect they maintained their nonQuechua language among the Chinca. This is difficult to tell because both the Inca and the Spaniards discouraged indigenous languages as weren't Quechua or Aymara.

What happened to Arab astrology?

Antoine Borrut has a book out, Astrology and History in Early Islam. You may read its introduction on academia.edu.

Several chronicles in the early centuries anchored themselves in astrologic observances... in Babylonia. The 'Abbasid moment was similarly Babylonian, at heart. So great astrologers invented mathematical tools... in London. Al-Khwarizmi had done so first. As Borrut points out, our modern disdain for astrology is postNewtonian. One is tempted to put a boldface over "post".

Devout Muslims like Ibn Jarîr Tabarî had disdained astrology before us, from a reading of sura 6 (the fifth for Ibn Mas'ud and Ubay). But old habits died hard. Christians like James/Jacob of Edessa were using astronomical tables to peg their annals; indeed the very annalistic form had come out of old Babylonian habits. This is in fact a major boon to us moderns, who can use their mention of eclipses, comets and even aurorae against what we know of the eclipse cycle and of visible comets, also lately tree-ring anomalies.

Perhaps universities should force history departments to install a mandatory astrology course. We could host it in the 200/2000 range.

Ancient liturgies

Short one for now: Philip Jenkins shows where to find lost text. Namely, embedded in other text, as the Didache is embedded in the Apostolic Constitutions, Jude in 2 Peter, and Aristides in the Life of Barlaam and Ioasaph. This blog has occasionally delved into Archaic Hebrew works in late Classical stuff like Habakkuk. Or maybe 2 Isaiah in the 1QIsa^a. Or all this stuff.

One fascinating thought is the ancient Christian liturgy. Paul in 1 Corinthians famously cites a formula of the Last Supper. Why would the Last Supper matter? Perhaps because everyone was already reënacting it. In fact the younger Pliny must report on a weekly ritual meal from Bithynia. The war of the Diaspora (mostly Cyprus and Cyrene) was approaching but Pliny's Christians were gentiles so wouldn't be affected. That liturgy was certainly the same as Ignatius was recommending at around that time.

But as Paul embeds some rituals of the, what, AD 50s; so other texts were embedding other rituals. Occasionally a gnostic text will involve people banding together to make some weird chant in a weird direction. Like the Acts of John section C chapter 94 - not just a hymn of Jesus, but stage-direction.

Proxima d

The inner planet of the closest stellar system to ours now has more evidence behind it. Kyplanet reports: interactions, with the chromosphere (above the photosphere which is the visible disc). Elsewhere reported: YZ Ceti, and the aging Sol-like HIP 67522.

Besides pretty-much proving that Prox d even exists, which I didn't rate obvious three/four years ago, we get some constraints on what d is. At M sin i of 0.26 M_⊕ it is rocky, with a magnetic field. The field isn't well constrained except that it's enormous. The sucker's enough to raise flares on a red dwarf. It's much greater than ours on Earth and might even be superJovian although Kyplanet doubts this.

Among the constraints we don't got, besides planetary inclination, would be a map of Prox' magnetic field. Zeeman Doppler Imaging has mapped such field for YZ Ceti - at 3.6pc: a sun's flares coincide with exoplanet crossings of the Alfvén surface as the planet orbit approaches the stellar magnetic equator. I suspect we can measure, by this, both the inclination of the stellar rotation relative to us; and that of the planet's orbit relative to the star.

Prox is closer us at 1.302pc. So that's a tool I'd suggest for the Prox team.

In addition: if some better-constrained nearby planets, like, oh, TRAPPIST-1 b, are not raising flares: is this because they are insufficiently inclined against their stars? I think resonant systems like this one might not be much so inclined.

As for Prox b, this may have a magnetic field too. It's too small and far to be inducing flares itself but the d-induced flares seem modulated by... something. The planet b is bigger than d so if d held onto a dynamo, why not b. Kyplanet is careful here to note that some of the outside interference might not come from b but from an "e" between d and b, or a retrograde capture inward of d (I find this unlikely).