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Comment by ythn | Hacker News Reader

I don't think it's dangerous. Light is too slow and space too vast

At human timescales, yes. Think of it from the other side - the immediate reaction to humans finding the existence of extraterrestrial life will be the start of an interstellar weapons program in every country. Now ask yourself what happens if an advanced civilisation reads the message, assumes correctly that these humans ought to have working weapons by now. They’re just going to dispatch a fire and forget drone and set a watchpoint to make sure we’re taken out cleanly.

Right back atcha.

On interstellar timescales, any civilization that fears we will develop interstellar offensive capabilities would need to also seriously consider the possibility that we would survive their first strike.

Some relativistically distant foe tries to wipe us out from some time in the past (light speed, so many many years ago). We recover from this event fully and locate the source.

Why attempt to retaliate? This would be like waging war on Italy for atrocities committed in roman times wouldn't it? Even if you could guarantee success, you have no information about the moral culpability of the target, and would have to assume they have lifespans many multiples of humans to assume any such quality, wouldn't you?

It's not about (justified) revenge, it's about security. 1500's Spain was as dangerous to the natives of the Americas as the Romans were to the Carthaginians 2000 years earlier. If some society didn't have qualms with attempting planetary scale biocide, who's to say their genetically practically identical successors won't do the same?

> Why attempt to retaliate?

Because retaliation shifts our foe's "risk of destruction if drone sent" vs "risk of destruction if drone not sent" tradeoff toward "don't attack".

Sure, but shouldnt really matter. It's very unlikely that any civilization launches anything from the homeworld, more likely they have the space equivalent roving nuclear submarines. Even if we survive the first hit, it's unlikely we can figure catch the launcher submarine or work out its homeworld.

The return-on-investment, time horizon, and C&C complexities are bad enough for one-off missions, they would be worse for an actively maintained fleet, and they would be abysmal for a minefield. How do you do IFF when latency is years / decades / centuries / millenia? If human history is any indication, you don't, and suffer the consequences. A planet-buster minefield is much more of a threat to you great-grandchildren than the new-kid-on-the-block aliens ever will be.

I don't find this scenario remotely convincing. A good premise for a scifi novel though.

Return on investment depends on both the return and investment. Once a civ hits Type 1 or Type 2, what they would consider an "expensive" investment is very different from what we would today. To a sufficiently advanced civ, destroying planets would be no more expensive than setting a sentry turret or an automated Predator drone.

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