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Microsoft develops ultra durable glass plates that can store several TBs of data for 10000 years
(unlocked.microsoft.com)
This is a most excellent place for technology news and articles.
I disagree with that notion, because while only 70 years, there's still ways to read punch cards as well. Sure, if society completely collapses and education will not be "reinvented" in 5000 years, those things probably won't be able to be read anymore. But the nuclear sign for example won't be changed anytime soon.
For that matter, how much smartphone evolved in the last 10 years, in 50 or 100 years, all smartphones probably will have a Geiger Counter (or we have those implanted).