The Dogger down under

This came in over Twitter this week, and yesterday Saraceni posted it so: Sahul's archipelago.

A common question in Australian prehistory is, "how come the Javanese and Islamic mariners never found Australia". Even the Polynesians may have been aware of the mainland; they absolutely got to what the Dutch call "New Zealand". I assume it a matter of time before they hit up Botany Bay from the east.

... and that's the problem. From the east, Australia's great bulk and mountain-range make landing not-horrible. The west coast of Australia is horrible: look at a map, and see how much nothing blocks winds between Malagasy and Perth. Speaking of, only the Perth corner is (relatively) human-habitable, I mean, if you're not into trapping small insectivores to survive. People do, today, live north, in the city of Darwin. Not many people.

So if Java, Islamic or Chinese-influenced or simply Javanese, had checked across the Timor Sea southeast of guess-where... they wouldn't have liked it. The landing was windy and treacherous. The local produce was bad, literally alien to a Javanese. There weren't many people there (anymore - we'll get to this) who could comprehend the concept of "trade". And there were shoals.

But. Once upon a time, those shoals were on the surface. They were islands - a chain of islands, parallel with Timor. The Tiwi Islands made a peninsula from Australia. Together they blocked a bay which is now "Joseph Bonaparte Gulf", "Malita Basin" on the gulf-floor. As for "Timor Sea": that was then more-like "Timor Strait". North Sea inhabitants might consider the Dogger Bank.

What was it like over there? Probably not far-off what Tiwi is like today - or even west Timor. With lower sealevels, in the Ice Age, the air might have been a bit cooler and drier. So less windy, at least. Kalumburu maybe? - either way, tropical-savannah with long dry seasons. October to May but more so December to March, monsoon.

Could people live in near-sea-level flatland with seasonal drenching, otherwise no water? With cisterns perhaps - but Ice Age people? @Paracelsus1092 finds this difficult to believe. There's where the Dogger similarities end; Dogger was eminently productive for birders and fishers, even for hunters when the full Doggerland Shelf.

It may be that these islands' main purpose was to make the climate less-windy and less-wavey for the inhabitants of what is now Darwin.

Maybe the Aussies could try this now. Build some artificial-islands and a submarine base or two.

The bow

We've looked at a few examples of south-to-north population movements up the isthmus - lately, bypassing Darien. Inasmuch as archery is a "Postclassic" introduction to the Maya and points north - that's another one [h/t saraceni].

Most of the Americas were doing fine with spearthrowers. Spears work better than arrows in taking down megafauna; and there's not much point in archery in a dense jungle where foliage gets in the way. Archery works for... well, for war. The Andes had war; the Huari and their Inca successors were (very) warlike.

Yes - the Huari were contemporaries with the postclassic Maya. But it is not like the Huari invented war. In this case the arrows point to Titicaca - which lake spawned that theocracy which the Hispanicised Inca will call "Tiahuanaco".

Tiahuanaco, perhaps, adopted the arrow for defence. They didn't like to face enemies in direct combat. But who needs to do that if their longbowmen turn your troops into pincushions from two hundred meters?

Resistance is futile

ToughSF has been essential Twitter reading lately! Here's Shanghai, bringing superconductors over 1.2 km. 2200 amps between two 220 kV substations. Resistance is, er, zero ohms. I take it that's power-delivery from the main grid to subgrids.

Mainly it's an economic problem they'd solved, namely they used their own stuff rather than buying it from, er, us. I still doubt if chilling a pipe with liquid nitrogen over 1.2 km is less expensive than just to run a current over copper and take the loss. Shanghai seem to think they've solved other problems: high electricity density and limited space. Next stop, Lagos, pop. 100 million, I guess...

As for deep space stations, this should be great, if only because heat-radiation is an inherent problem. And Jensen was going to settle millions of people on his spinning rubblepiles. Main problem I see is the inherent expense of nitrogen itself.

WREN

ToughSF is talking up Florida man Herbert Wertheim Wave Rotor Enhanced Nuclear... Propulsion. They've silenced the P so - WREN for short (powerpoint). I don't suppose he'd like to be called HerbeWert.

Wertheim offers 444 W/kg electric cycle, 1920 W/kg thermal cycle, Isp 1430 (N/N)s (thermal exhaust 1420s per ToughSF). Its propulsion is indeed bimodal, with the thermal side being good ol' NERVA. Otherwise it is nuclear-electric, when the Isp rises to 3000 with accompanying dip in thrust.

It's being earmarked as a 45 day trip to Mars in microgravity. Afterwhich I guess the Martians have to stay there.

Although the tech is ToughSF-approved, I approve it only as a ferry (and can't we find closer targets?). I repeat - assuming we want Mars at all - we should be setting a permanent spinning station on Deimos. With that set up, by robots, we humans can get spun back to good ol' 9.8 m/s².

EtaVolt's rolling solarpanel mechanic

ToughSF brings some Christmas cheer for those dealing with heat-damaged solar-panels: the Singaporeans can fix them now (pdf). Light and heat can be assured most of the damage if we're running these panels in the 0.7-1.0 AU band like I want. (Meteors remain an issue, yes.)

The device would roll itself over solar panels that are up to 2.3 metres in length. I assume that means under gravity. If the station is spinning, which any manned station should be, that means turning the panels tangent to the spin-direction, and rolling that device accordingly.

The eve of the anointed

We're coming up to the fourth week of Advent, so - let's post something. How about: when is the Nativity. This is coming up because Kevin Sorbo, a man I used to admire, lately tweeted that "atheists" shouldn't celebrate Christmas. Mike Cernovich and others have responded that it is a secular celebration of joy which we don't have to name "Christmas". Still more are commenting that most of this stuff is midwinter paganism.

Our local gym has menorahs, stars-of-david, and evergreen decorations with nary a cross nor manger in sight. Equity trumps inclusion, as ever. And they wonder why the young generation despises Christians and resents Jews. At least they've spared us rainbows this time.

Previously I'd been aware of Hippolytus insisting on 25 December - with the assumption of the 25 March Easter. I'd also been aware that Clement in Alexandria had been aware of several dueling days for this Mass.

What Andrew McGowan is larnin' me here is that Origen... gave up. Origen anticipates modern Salafists on Muhammad's birthday: G-d is eternal, He has no birthday. Leave these things to the pagans; leave these things to the liberals. The Puritans, later, would agree.

If Sorbo wants to be play Puritan then he'll likely not even see evergreens allowed anymore.

...sheep a'lambing

I've got an 'Eve poast upcoming but in the meantime, let's get a jump on Easter. This is the real Christian holiday as you know. When's that?

Passover - duh. But there remain some questions on when, exactly. The Johannine Gospel presents Jesus as the Lamb; as do John of Patmos, and Paul. Jesus would have died on 14 Nisan/Artemisios. Mark disagreed and said, 15 Nisan; the other two follow Mark.

But what if... Luke didn't? I have in mind that Luke's Nativity has (famously) shepherds in the field. This is when lambs are born in the first place: that's before mid-Nisan, but not long before. Certainly not midwinter.

A few points follow. (1) Luke did not compose the manger scene himself since his Jesus is the sin-offering, not the Lamb. (2) The L source here, clearly neither Mark nor Matthew, agreed with the Johananaym that Jesus is the Lamb.

These would tempt Johannines to prefer Easter shifted forward in spring; they could possibly get some L/protoLuke-believers, like Marcion, aboard with this as well. Clement (who was not a Marcionite) recorded Nativity options to run late with the singular exception 25 Pharmuthi (21 March), rendering Clement unserious for the Passion. Orthodox Passion, by contrast, looks credible: 14 Artemisios, 6 April (7 in Armenia).

This has... implications for Bcheiry, incidentally, as Isho'yahb bishop of Nineveh celebrated an Easter miracle in the very day-of-month of that original Easter. Bcheiry assumed 25 March. Should it be 25 March, in 630s AD Nineveh?