nostr:npub1jhyrgsw7r2el2xymduhx9pqsvpkrnz9k5etam5fln75nqsm9cy3qlu5uhr nostr:npub194h76frd3mdsp67fn85kdemcn8m0ur5e6qcflnwwap9q25gwj96qdj4ewx In doing public outreach about astronomy years ago I used to point out that GPS has to take General Relativity into account. GR isn't just some entirely abstract irrelevant idea.