Five-hundred years ago the population of Rapa Nui mysteriously lost their ability to erect Moai. They were great works of art. One unfinished statue if completed, would have been seventy feet tall and weighed one-hundred and fifty tons. Whatever happened occurred relatively suddenly. The community never recovered
In the 1950s, the British Museum came into possession an ancient glass chalice called the Lycurgus Cup, so named for the depiction of Dionysus’s triumph over King Lycurgus of Thrace. The decorative object exhibits a strange optical phenomenon. Under normal lighting, the glass appears jade green, but when lit from behind, it turns ruby red. Created during in 4th Century by those unknown the requirements needed to make it remained lost in time until 1990. Scientists using ultramodern lab equipment in a lab were able to deduce effect was created by including gold and silver particles ground up finely to about fifty manometers in diameter, or less than one thousandth the size of a grain of salt.
Artist David Hockney and physicist Charles M Falco made a discovery around the year 2000. The Hockney–Falco thesis shows that the advances in realism made by The Old Masters was primarily the result of optical instruments like camera obscura, camera lucida, and curved mirrors. At some point between the 16th Century and 2001 that understanding was lost. It was rediscovered but it’s still partially lost and it always will be.
Knowledge is now stored on the Internet. But it may not be safe. There is no such thing as the cloud, just other people’s computers. The internet isn’t ephemeral, it’s a fungible collection of hardware laced around the globe. In 1859 a solar astronomer called Richard Carrington was observing the sun from his private observatory in Surrey, England. As he was sketching a large group of sunspots two extremely bright beads of white light suddenly appeared over the sunspots. Five minutes later the white beads had gone. The Carrington Event was in fact a gigantic solar flare. It hurtled a cloud charged particles towards Earth over a period of days. When the particles stuck the planet they caused brilliant auroras from the poles all the way to the sub-tropics. The magnetic disturbance also destroyed electric telegraph systems all over the world. Wires shorted out, operators received electric shocks, and sparking discharges set fire to the paper in telegraph receivers. There was another Carrington Event in 2012 but it fortunately missed Earth.