Well, one thing we don't know physically is whether traversable wormholes exist
https://en.wikipedia.org/wiki/Wormhole#Traversable_wormholes
Even if all travel is limited by lightspeed, without knowing the probability of emergence of intelligent life, we don't know how far away or how long ago such life is likely to have formed.
Even if we did have a better idea about this probability, we still couldn't rule out that intelligent life had by chance formed relatively nearby, relatively long ago, thereby allowing them to reach us by now. Nothing in physics forbids this as far as I know.
Personally I don't think an advanced alien civ would attack us anyway, because we'd be no threat. Since intelligence seems to imply curiosity, they might want to observe or experiment with us instead, but that's speculative
> Even if we did have a better idea about this probability, we still couldn't rule out that intelligent life had by chance formed relatively nearby, relatively long ago, thereby allowing them to reach us by now.
What is "now"? Within the next 100,000 years? In human terms, that's an eternity, and in galaxy term, that's an insignificant amount of time. In other words, almost certain not to happen. Even if it does, do we even notice? Chances are they either immediately kill us all, or they just observe and will stay hidden. A face to face interaction is scifi, not reality.
Tbh, on the list of things that humankind should worry about, an alien visit isn't even in the top 100.
It's understandable that it's a great topic to muse about, especially among tech folks. It's been part of scifi lore for generations and one can spend a lot of time discussing technical aspects. That's by far less messy and depressing than dealing with actual real-world problems (like wars, drift to dictatorships, oppression of minorities, inequality, climate crisis, human-made ecological disasters, heritary or contagious diseases, etc etc). Though when it's about devoting actual societal resources, it would be a waste to spend them on alien visitor questions beyond writing novels and making movies. Even if it's more fun to nerd out on intergalactical travel rather than preventing school shootings.
> What is "now"?
"by now" means at some time before the present.
I'm just pointing out an alien encounter is not ruled out by physics. I'm not advocating for societal resources to be diverted to prepare for it.
You mention some well-known, difficult problems. Does their existence mean no one should ever talk about anything else?
I'm not sure why you get involved with a conversation just to point out that wars and climate change are happening. Everybody already knows that. I'm taking a little time out to comment on various topics here, as you seem to be doing too.
Anyway, if you're trying to encourage people to spend time on finding solutions to those problems, I'm listening. What's your proposal?
Sorry if I got you on the wrong foot. I was merely generally rambling, not critcizing you personally or your point. Of course it's fine to discuss this, just like it's fine that people discuss pokemon or cool jazz (who am I to judge). I could have posted this anywhere in the discussion tree. I'm merely a little fed up when some tech folks make it sound like this should be top priority for humankind.
Of course you're right about the physics.
And I don't have solutions to the hard problems either. They are hard for a reason.
Ah ok, thanks for clarifying. I certainly don't think it should be a top priority either, partly because of the low subjective probability, but mostly because it would be an outside context problem (excession) - it's impossible to prepare for an event whose implications we can't bound
https://en.wikipedia.org/wiki/Excession#Outside_Context_Prob...
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