What is the origin of the lake tank image that has become a meme? (2021)

> The photo was taken about coordinates 50.29092467073664, 4.893099128823844 near modern Wallonia, Belgium on the Meuse River.

Great writeup, but I did have a little chuckle reading "it was taken about near here", followed by coordinates precise enough to identify a single atom. https://xkcd.com/2170/

Going to be a different atom once you walk near. Or temperature changes, the wind blows, and so on.

We’ll need to give each atom a unique ID. That would solve the problem.