At 07:07 PM 23/07/2019 -0700, you wrote: It's not a 'small amount of lost information', because destroying rare technical works in order to scan them, or afterwards because "now they are scanned there's no need to keep the paper copy" is a widespread practice. Very many works in original form are being lost because of this. Let me tell you about my wife. She's Cambodian, and very barely lived through the Pol Pot genocide in Cambodia. Many of her family and relatives didn't make it. The Khmer Rouge were mostly insane, as a result of the secret US bombing campaign, in which they napalmed every Cambodian country village they could spot. So virtually all country folk in Cambodia had lost people close to them to poisonous fire from the sky. (Napalm contains phosphorus, can't be extinguished, and even if you only get a few spots on you and survive the burning, you die slowly of phosphorus poisoning.) The countryside people were virtually all uneducated and knew nothing of the outside world, and had no idea why this was happening. In this context the Khmer Rouge arose, with the central creed being that Cambodia had to be purged, since all 'foreign influences' equated to the burning from the sky. By 'purged' they meant _everything_ and _everyone_ with any trace of foreign influence. That included all the people in the major cities, since they spoke with foreign (French, Chinese) accents among other things. It also meant all machines and books. Did you know sewing machines are evil? No? Well they were to the Khmer Rouge, so they destroyed them all. As a result my future wife (from Phnom Phen) spent several years on sub-starvation diet, only kept alive in a camp because she could hand-sew uniforms for the Khmer Rouge. As in needle and thread only. I guess needles and scissors were not considered 'machines'. Ditto rifles. They weren't big on logical consistency. The camps were intended as temporary people storage, while they sorted out who to kill. Almost everyone, though there was a lot of mission drift. They didn't have enough bullets, so the daily killings were done via simpler, zero cost means. A common method was for three people to kill one. Two held the victim's arms back, pulling them against a tree trunk. The third sawed through the victim's throat with the edge of a palm frond. This happened very often, daily. We met and married here in Australia, had a family etc. Wonderful person. But her past haunted her and she slowly developed PTSD. Is far from who she once was. This is why I dislike the practice of destroying things (information and still useful tech-tools) for reasons that seem sensible to some, but are fundamentally superficial consequences of social fads and groupthink. It's a mindset - destroying old things, and destroying people, go hand in hand. If you can justify one, the other maybe too. My sense of scale is OK I think. There was a major global human genetic bottleneck around 12,000 years ago, probably caused by the metorite impact that left the Hiawatha crater in Greenland. That one nearly wiped us out. About 30,000 years ago 'something' caused a mega-tsunami that washed right across the north end of the southern island of New Zealand, creating the 'buried kauri forests' effect. There was a relatively high-tech civilization in the Mediteranean area sometime around 300BC, that made the Antikythera Mechanism - that one required mathematics, accurate astronomy, metalurgy and precision machine tools, plus all the necessary cultural support. Completely lost. The Umm al Binni lake (in Al Amarah marshes of southern Iraq, approximately 45 km northwest of the Tigris-Euphrates confluence) is believed to be a Holocene (8,000 BC to present) impact crater. There are traces in ancient texts of a prior civilization in that area that was apparently completely wiped out. Just a few of a long list of dramatic natural events in quite recent times, very little known by the public. Currently humans have achieved a pretty nice level of technological capability. But few understand how fragile that is, and what kinds of events could crash it back to primitive levels. Very very few are aware of factors like tech being not easily restartable, since we've used up all the easily mined resources, now running on ores and energy sources that require existing high tech. Almost no one is aware of the long-life isotope stocks issue, that could make a technological collapse permanent for many millions of years, by raising background environmental radiation worldwide to levels untenable for higher life forms, if our radioactives containment facilities were degraded during even a hundred years of no-tech. And ALL our existing digital storage media are very ephemeral. Factors like these, make detailed, robust and widely distributed _paper_ documentation of technological artifacts *much* more important than most realise. They are 'safety margin.' Always maintain a good safety margin, in anything life-critical. Guy