Then there’s the possibilities for pre-human advanced civs. No less an establishment figure than Gavin Schmidt has nibbled at that:https://www.theatlantic.com...

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Possibly related trivial tidbit: Since at least the 2nd century AD, this concept has been a frequent interpretation of the "Nephilim" mentioned in Genesis chapter 6.

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«Of course, the Persian Gulf was flooded by ~6,000 BC, so it will be very expensive to determine if the first cities' appearance in Sumer shortly after this flooding was really a coincidence»

The sumerian myths along with the vimana etc. in the Mahbarata, the "vara" of the iranians, and the greek myths of an age when "centaurs" and "gods" mixed with humans are some of the most startling hints that some ancient high civilizations may have happened in the "recent" past, that is this side of the ice age.

I have read that the sumerian myths are so popular among "speculative" historians that assyriologists now prefer to publish in german archeology journals to avoid their attention.The problem is that those myths are really really "strange", so I sympathize to some extent with the "speculative" historians, in particular the details about the relationship between the sumerians and their "gods":

* The sumerian origin myth is that they were designed by their "gods" by modifying their "blood" to do the hard work instead of them, and that they were redesigned twice because they were multiplying too fast. That's a pretty self-deprecating origin myth, and the details in the story are interesting.

* One of the details is that when talking of their gods and themselves, they describe themselves as "the black haired ones", implying that their "gods" had hair and it was not black.

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«The 50-60 kya out-of-Africa evidence»

There are alleged human habitation signs including footprints in Europe and other places up to several hundred thousand years ago. That is somewhat disconcerting, but it seems that humanity is much older than thought.

That is compatible with the “50-60 kya out-of-Africa evidence”, as long as it is not assumed it was the first case.

The history of humanity may be a lot less linear than what "whig" historical philosophy prescribes.

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«Many of these older sites have very large tunnel systems, many of which are from being fully explored. That is my best bet re where to look for evidence of lost advanced civs.»

Maybe, but apart from now underwater river estuaries (a favourite of many is that of the Saraswati because of the Mahabarata description of "vimana" powered by a "yellow liquid" fuel) I would look around the southern Urals for the "vara" of the iranians, described here:


"O fair Yima, upon the material world the fatal winters are going to fall, that shall bring the fierce, foul frost; upon the material world the fatal winters are going to fall that shall make snowflakes fall thick, even on the highest tops of mountain""Therefore make thee a Vara [a hypogeum, or underground enclosure] long as a riding ground on every side of the square, and thither bring the seeds of sheep and oxen, of men, of dogs, of birds, and of red blazing fires… Thither thou shalt bring the seeds of men and women of the greatest, best and finest kinds on this earth; thither shalt thou bring the seeds of every kind of cattle, of the greatest, best and finest kinds on this earth. Thither shalt thou bring the seeds of every kind of tree, of the greatest, best and finest kinds on this earth; thither shalt thou bring the seeds of every kind of fruit, the fullest of food and sweetest of odour. All those seeds shalt thou bring, two of every kind, to be kept inexhaustible there, so long as those men shall stay in the Vara. There shall be no humpbacked, none bulged forward there; no impotent, no lunatic… no leprous.""Thereupon came Angra Mainyu, who is all death, and he counter-created by his witchcraft the serpent in the river, and winter, a work of the demons… [Now] there are ten winter months there, two summer months, and these are cold for the waters, cold for the earth, cold for the trees. Winter falls there, with the worst of its plagues.""In the largest part of the place he made nine streets, six in the middle part, three in the smallest. To the streets of the largest part he brought a thousand seeds of men and women; to the streets of the middle part, six hundred; to the streets of the smallest part, three hundred. That Vara he sealed up with the golden ring, and a he made a door and a window self-shining within.O Maker of the material world, thou Holy One! What lights are there to give light in the Vara which Yima made? Ahura Mazda answered: “there are uncreated lights and created lights. There the stars, the moon and the sun are only once (a year) seen to rise and set, and a year seems only as a day."

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There is a saying "when it is steam engine time, it steam engines"; related to that, when there is sufficient population density and food surplus an a culture that accepts change, there should arise an advanced "machine age" civilisation.

This may well have happened several times in the past half a million years. I would even guess it has happened, at least a few times.If there are no obvious signs of that it is because in part we are not looking for such signs, and in part because time is relentless, and we are not talking about a few thousands years between them, but probably 10s of thousands, and perhaps even 100-200 thousand.

As a rule advanced centres of civilisation happen on rivers, and particularly on estuaries. One problem is that sea levels are much higher than normal, and if there are remnants of them they have under quite a bit of water.Another way to detect potential very high machine civilisations would be to radar scan the surface of the moon for lunar landers and their metallic echo.

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Fair. We can't say that none have them, just that we never never seen any evidence of artificial satellites around any of the planets that we have investigated.

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Can you link to a reference re the long-term stability of geosynchronous orbits (vs. resonance with the Moon, etc.)?

I don't think we can say that there are no non-human artifacts orbiting any body in the Solar System. Even Earth. How would we know that?

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Ah yeah. It does read as though the assumption is that sim consciousness is possible though.

More generally, I do think when people discuss this it often reads like they're assuming it's possible for simulated people to have consciousness and/or just not discussing the issue.

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Lots of technologies were lost in the medieval period:

ball bearingshorse operated millsfloating waterwheelspiston pump

More on the luxury side: magnifying glass, Lycurgus Cup, Antikythera mechanism

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Hancock comes from a clerical family and sermonising is in his blood; that’s why he’s a journalist. His sermon is: there was once a great civilisation, but it died through hubris and vanity; we could suffer the same fate, unless we abandon greed and technology and get in touch with our feminine side—along with the hidden ways of spiritual wisdom (probably acquired by huffing cannabis and drinking DMT, people like a spiritual justification for their vices). His idea of an ancient mysterious civilisation provides a God-like hint of eternity. This sermon is the main product he sells; it’s quite attractive in a godless society and his evidence is selected to fit his sermon, not vice versa. Jeremiads never go out of fashion.

However, he is also correct to point out that the debate around Clovis First and Göbekli Tepe, in different ways, were examples of cases where people with dissentient views were marginalised and ridiculed before being accepted.

His complaint that expert communities can be narrow-minded and often ridicule and marginalise ideas that later turn out to be true is correct (the Semmelweis factor). I suppose rationalists might be interested in the way Hancock highlights how professional archeologists and the like are often biased, even though they think they’re rational and objective; but I’m not a rationalist or a technical person, being more irrational and intuitive by nature—perhaps rationalists carry no water for Hancock.

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Those two authors are central to all the links I followed. Modern isotope and genetic data has reshaped and continues to reshape our scientific understanding of the evolution of hominids/civilization and the climate/ecological contexts in which these transitions occurred.

The 50-60 kya out-of-Africa evidence and the LR04 Benthic Stack are radical redefinitions of our previous scientific knowledge. It is sad that many of our finest minds are unaware of these magnificent empirically written stories and instead re-iterate the misinterpretation of the same data by Hancock and Carlson; a misinformed social meme now widespread due to Joe Rogan's podcasts.

You may not have endorsed those authors, Robin, but you are riding the wake of their pseudo-scientific meme.

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In my poll, that would be (B), which includes sims being impossible.

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I did not endorse those authors.

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I am surprised at how prevalent the views of Graham Hancock and Randall Carlson are in various "technical" and "rationality" communities. The cornerstone of their lost ancient civilization narrative is a cataclysmic event around the time of the Younger Dryas. From my perspective, this stems from a misinterpretation of the delta-O-18 data. This data is often plotted as delta-temperature-equivalents but, as Lisiecki and Raymo's LR04 Benthic Stack demonstrates, these values are best thought of as the amount of fresh water "trapped" terrestrially in the form of glaciers and/or lakes.

The parsimonious explanation of the Younger Dryas is that several meltwater pulses occurred as the proglacial lakes like Algonquin, Iroquois, and the Champlain Sea suddenly released fresh water via various well established routes to the Atlantic. The exact same pattern should have occurred in each of the pervious terminations of the 100 ky glacial cycles. The oddity to be accounted for after the termination of the last glacial maximum is the extinction of the megafauna that survived the previous terminations.

The baseline is normal 100 ky glacial termination processes and the evidence is fully aligned with this baseline. Comet impacts could complicate this baseline in interesting ways but I can't see how to interpret Hancock and Carlson's views as anything but wishful pseudoscience.

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Robin, comment on Bostrom poll on twitter as I've deleted my twitter account.

I think you need an option that Bostrom's theory may be wrong because simulated people may not have consciousness.

I think the best we can say on that is it's 50:50.

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