We know how we are handling space exploration. We send robot probes. So once you get good at space travel. You set up automated factories on an asteroid and just churn out probes. Scattering them all over the universe looking for radio waves, nuclear explosion and polluted planets.
Imagine what it must have looked like to the swarms of interstellar probe cruising between the stars, when we detonated Ivy Mike or when the Russians detonated the Tsar Bomba. They would all come running like moths to a flame.
https://en.wikipedia.org/wiki/Ivy_Mike
https://en.wikipedia.org/wiki/Tsar_Bomba
I feel I should point out that the civilizations who did this are probably long dead or just don't care what the probes found. After thousands of years they are gone or have moved on. The probes are just on auto pilot.
Their deaths aren't that big a surprise. Look at human history and pre history. It's always the same story, poor sanitation, environmental degradation, corruption and climate.
Look how people responded to covid.
I strongly recommend two books by Jared Diamond, Guns Germs and steel, and Collapse.
https://en.wikipedia.org/wiki/Guns%2C_Germs%2C_and_Steel https://en.wikipedia.org/wiki/Collapse:_How_Societies_Choose_to_Fail_or_Succeed
Naah I don't buy it. Individual cities and countries collapse, but not anything larger. Also, poor sanitation throughout history was mostly because of a lack of understanding of germ theory.
Nawww, I was thinking more of a secret nihilistic text or something. Something that just makes an entire civ kill themselves or something. Or maybe some equation that spells eternal doom or something that leaves everyone absolutely hopeless.
I'll try going through the summaries of the books you recommended! Thanks :)