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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.
If we know that the material can go 10k years without degradation, which is something we can know, then it can last that long. Will it be practically possible to store it in a way that will allow for the maximum amount of time before the material begins to degrade? That's a whole other thing.