nostr:npub1tfxfz24qp6zykjngnxvp26fhztlj8h8srrf327afhtyy28rnptwshqn4hu nostr:npub1zdp33shl69xr0uq3x8n5gsjykq9upycwh6nqm02c3f6x0frrn0dq42vqv8 

Bridges.

Gravity works the same way everywhere in the universe, and bridges are shaped the way they are because of gravity. This means that bridges on any planet will assume similar shapes. An alien civilisation may have different ideas of language, transport, food and society, but their suspension bridges will look a lot like ours. This will instantly get them on our side and help them realise common cause with us.