Ask HN: Human Independent Sources for Timestamp?

[azatom]

What are some options for a timestamp, like a pattern of sunpots, not a human related thing like dedicated timestamp authorities?

(Even chatgpt won't give me any idea, just forces the use of authorities, even after a long converstation said to make photos of newspaper, after my example was the daily titles of 20 bigest journals.

[robga]

On the macro scale, would measuring sidereal time or pulsars meet your requirement? On the micro scale, atomic clocks?

[azatom]

No, I meant by a timestamp a thing, that assures other people, that another thing certainly does not happened after a specific time. There are authorities, whose in a simplified way: - I take crypto-hash of a massage, send to a timestamp authority - That authority digitally sign it with adding the current time.

So other people can check with the authority's public key, that is valid, so what I hashed, I cannot created after that time.

edit: so there is a problem with sunspots, it assures that it happened not before