Remote nuclear fission powered database.
Somewhere in the world some guy has a remote nuclear fission powered database underground which is recording hundreds of instances of the entire internet per hour. When the sun turns into a red giant and turns the planet into toast, aliens will come to mine earth millions of years later, they will come across this recorded internet. They will learn about Hitler and his supposed reign of terror. However, they will also see that others have pleaded Hitler did nothing wrong, leaving them in a mystery and it will become the most debated topic among their entire race. Thank you for leaving your mark on the universe.
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