Hookes Monument, Sundaland
Finally Read Quicksilver by Neal Stephenson, - took a while to get into it, dense, lotsa research, might look for "Confusion" and "The System of the World" vols 2 & 3,
Best joined with some non-fiction like John Gribbons "The Fellowship" , The Royal Society, Newton and all that.
Great characters, great minds. The politics is complex. For an Anti-Royalist the carnage done in Ireland hurts my heart.
Robert Boyles brother helped crush the Irish rebellion , so the Boyle got his father's (Earl of Cork) 'estate' back - this is 1643, before Cromwells invasion of 49.
Gribbin says "he doubted his right to take an income from such an impoverished country, but" ... reader, he did... £3,000 pa
I am rather fond of Robert Hooke, who wasnt from a nouveau rich family like Boyle." Hooke always took care to address Boyle with 'due deference'"
Hooke made a bunch of money surveying London after the great fire, but after his live-in niece died he became 'withdrawn'. Eventually became miserly, afraid the money would run out, didnt even buy decent food. Know the feeling. He left a chest with £8000
Seems he came up with the inverse square-law for gravity, but lacked Newtons maths. Newton was asked to mention him, but snarkily did the reverse, crossing out most occurrences of Hookes name.
I also lack the maths. I could have followed it in high-school. But damn it all, its full of slippery approximations. Stephenson has an image whereby Newton apparently 'proves' that the gravity of an extended body acts as all the mass is concentrated at the central point.
Evidently the 'proof' is geometrical, not from the calculus. '
Its obviously an approximation, but we stand well enough on this rocky sphere.
"In this way it can be shown that an object with a spherically-symmetric distribution of mass exerts the same gravitational attraction on external bodies as if all the object's mass were concentrated at a point at its centre. (This is not generally true for non-spherically-symmetrical bodies.)"
but this breaks down if I actually touch down on the sphere and touch a piece of the limb - zero distance, infinite attraction...
The weird thing about the Inverse Square' law is that 2 bodies must never touch, lest infinite attraction result!!!
So Rutherfords atom could have been deduced in a thought experiment. If I hold an apple, the 'mass' particles of the apple and my hand obviously are not quite touching. If they touched, infinite attraction would squash them together.
A repulsive force stronger than gravity must intervene and keep the masses apart some finite distance. Hence electrons, nucleii.
OK google principia and extended body "
Physics forum has this re-assuring answer [yes it is approximate]
The point is that the CM is not just 'an approximation'. To be reliable it has to have clear constraints on when it is inaccurate and an accompanying formula for the error. This of course is not in your physics textbook. When the proper constraints are applied to the CM Theorem (i.e., it's only really valid between masses whose distance dwarfs their size) it becomes a mere truism in any case, and is not needed
For relatively close distances, such as at the surface of the earth, the Theorem and method for calculating the force using the CM is grossly inaccurate, and results in an actual miscalculation of the 'constant' portion of the Gravitational Constant (G). The current G in Newton's Gmm/d^2 formula for the force is functional as a coordinator of units, but is in fact not the real Gravitational Constant. That must be teased out of the apparent constant after the corrections have been made for the inaccuracy caused by using the CM to calculate the force.
the calculus 'aproximate proof' is here
NS claims that Hooke designed 'the Monument' commonly known as Wrens tower. Recommended to visit if in London, 61 metres 1671-7 at the time the tallest freestanding stone tower
Climate Change in Prehistory
The End of the Reign of Chaos
William James Burroughs
mentions Dansgaard/Oeschger [DO] events
"sudden climate change" essay. Most of what I did was to take Jonathan Adams’ long and detailed Web Page
The Eemian interglacial seems to have ended in a sudden cooling event about 110,000 years ago
the main Younger Dryas-to-Holocene warming (about 11,000 years ago) took several decades in the Arctic, but was marked by a series of sudden steps in warming, each taking less than 5 years. About half of the warming was concentrated into a single period of less than 15 years.
a sudden cooling event, about 8,200 years ago and giving cool, dry conditions lasting perhaps 200 years before a rapid return to conditions warmer (and generally moister) than the present.
note that Stephen Oppenheimer's 85K ypb low doesnt appear on this chart
amazing how difficult it is to find decent temperature and sea level charts for the paloelithic 140Kybp on the internets
But this sealevel chart does show some 85K drop.
Stephen Oppenheimer (SO) reckons that modern Humans left Eritria, points East to Australia at 85K ybp because the cooling dropped the sea slightly, choked the Bab El Mandab (Gate of Grief), not completely, but enough to make the red sea too salty for oysters. Oyster bars are seen in Eritrea aged 125Kybp, RO thinks that Modern Humans didnt cross to the Aden side because dangerous Australopithecus were already there. Until the oysters ran out and hunger drove them.
Legends about floods and Red sea crossings...
So Modern Humans were in Malakka before the Toba eruption (74Kybp)..
SO has a book (I havnt read) about the continent of Sunda, which formed by low sea level in the last GlacialMax 20Kybp - a huge area joining Java to Palawan ( but not RP)
This may well have been the origin of civilization. When the heat came back (14Kybp) the place was drowned. 9 wise men turned up at Basra to found Mesopotamian civilization.
The Sunda peoples probably had boats to cross the Wallace line to Flores & Aus.
The bulk of the submerged Sunda Shelf was inundated relatively rapidly between 14,000 and 11,000 years ago . Whilst much of the territory would have been lost in the first of three 'global superfloods', 14,000 years ago, almost all the antediluvian continental shelf would have been inundated during the second flood roughly 11,000 years ago . The only significant event of the third superflood of approximately 7,500 years ago would have been the opening of the Strait of Malacca between Malaya and Sumatra . If we forgive him for omitting the first flood, either Plato's observation of events 11,600 years ago is just a fluke, or we could justifiably speculate that the Egyptians did keep records, or atAlso
least traditions, that dated back to the epoch of 9,600 BC
DNA research led by Leeds University’s Martin Richards, one of only two professors of archaeogenetics in the world, supports this idea, showing that the stone-age people on the southeastern shore of Sundaland expanded across the newly formed island chains 12,000 years ago.
The new theory, published in the journal Molecular Biology and Evolution, is likely to draw bitter criticism from supporters of the old consensus, based on linguistics, that the area is populated today by descendants of a rice-growing people called the Austronesians who expanded from Taiwan just 4,000 years ago. “Some quite forceful archaeologists have been extremely reluctant to accept this,” says Professor Richards. “And I haven’t met a single linguist willing to give up the out-of-Taiwan argument.”
The Austronesians supposedly supplanted the indigenous hunter-gatherers, who first arrived 50,000 years ago yet were considered so insignificant that they have not even been named.
“That was a great mistake,” Professor Richards says. His team is the first to use the full mitochondrial genome rather than fragments, giving it a much more detailed picture of population movements in the distant past. Their results show that the biggest migration went not from Taiwan, but to it, and occurred much earlier.
Another ice age drowned continent joined Lanka to India - pre-vedic civilization?
Timeline of glaciations
(apologiies for previous draft, too many Roberts)