The aliens would have superior tech, so hacking into our systems would be trivial. They could just launch an actual nuke rather than lobbing one in from space.

People assume this and I never understand why. Even if we postulate highly complex realtime computing as a necessity for controlling a superluminal engine, why assume an entire technological history unrelated to ours would make it trivial, or for that matter possible, that even FTL-capable extraterrestrials can compromise earthly systems?

'The thing about aliens is they're alien.' - why assume this only works in one direction?

You're assuming that the aliens are alien.

If there's a reason to assume otherwise, I've yet to become aware of it. Or are you getting at something more earthly in scope?

A common trope in sci fi is that aliens are actually people from the future traveling back in time

Or from the same planet but spread out via FTL travel either ships or wormhole gates. After all, we were made in the image of THE creator, right?

Speaking of Golden Age twists! And not fully thought-through ones, at that. It requires two assumptions: first that there exists a yahweh-style creator deity, and second that Genesis 1:26 is accurate to fact. Even taking both as axiomatic, this approach still further assumes that this likeness, namely the one in which we as humans are made, must also be the only likeness in which a mortal could be made after its creator.

Given the assumptions of faith under which we here labor, it may also be wise to heed 1 Cor. 2:11, in which the convert Roman makes one of his few worthy statements in warning men against imagining they can know the mind of God. In that light, the proposition lacks soundness even under its own axioms.

>It requires two assumptions:

You're kidding right? It's all SciFi. In case you're confused, the Fi is short for Fiction. Stuff that's not real. So of course we're making assumptions on the entire thing. Including The Book as the greatest selling book of fiction of all time.

You're also now assuming that we Earthlings are the original source. Some scifi tropes state we're more Martian fleeing their dying planet or with things like panspermia. I like the SciFi where everyone is searching for the nearly mythical planet that turns out to be Earth. Ice Pirates is a goofy one.

You may labor under a misapprehension here; if I met Yahweh on the road, I would do my level best to kill it. But I was raised with that book, and still remember enough to play with the toys in it when I want to; if we're talking 1950s sf twists like "the aliens were fellow children of God all along!" then those are the toys with which we're playing.

That aside, of course we're making assumptions. But if we don't choose to either be bound by the assumptions we've already made or re-evaluate them, then we're playing with dolls rather than worldbuilding. Your pastimes are of course your own business, but it's been a long time indeed since I graduated from the former to the latter.

(Not that I mind space opera, when it focuses on the character-driven stories it's best suited to tell - trying to figure out how a TARDIS works misses the point entirely, while "The Doctor's Wife" is beautiful. But you mentioned science fiction, and my current standard there is set by Children of Time and Blindsight.)

Thanks for the recommendation of Children of Time. A few others from me: https://news.ycombinator.com/item?id=39322944

That's fair; I suppose I am assuming this story doesn't have that kind of Golden-Age twist in it...

That does not seem so far fetched to me. So many of the purported alien sightings are beings with bilateral symmetry, two eyes, two arms, humanoid face and so on. The only way I could see that happening is visitors from a distant future.

Or, more likely, the alien "creators" have created them more or less in our image.

It's quite possible that the humanoid lifeform is optimal to have a technological species that can travel between stars. An aquatic species would have huge difficulties just building technology and civilization, because of the habitat. A species without arms and thumbs would have a hard time manipulating its environment (just look at all the 4-legged animals now). A species with more than 4 limbs would likely either be too small (insects) to accomplish much, or would need too much energy (and probably evolve to lose the extra limbs over time).

There's good reasons to think that alien species might not look all that different from animals on this planet, simply due to physics. Animals here didn't simply spring to life in their current form; they evolved from single-celled organisms to best suit their environments.

The word 'parochialism' positively vaults to mind.

Another possibility is that the Galactic Federation has a rule that when they need to visit a planet that is not yet aware of aliens the crew must entirely consist of beings that have the same general form as the people of that planet.

That makes it harder for someone who sees them to convince others that it was aliens and not just a trick of bad lighting or someone with deformities or injuries that give them an unusual appearance.

It also makes it less likely for them to be mistaken for some other species on the planet. Suppose the Federation sent an expedition to ancient Earth that included crew from a species that looked a lot like our cats, and accidentally let Earth people get too good a look at them and their technology.

Those Earth people might think those are Earth cats, and conclude that Earth cats are a lot more powerful and advanced then they thought, and that they had better stop treating cats like animals lest the cats decided to wipe them out and start treating them as superior beings. Next thing you know that entire civilization is treating cats as magical being of great value or even worshiping them as gods.

Having owned (or more properly cared for) cats, I've always been a little suspicious.

They would compromise the systems by dumping nanobots into them which rewire the whole thing, not by breaking the encryption.

I always assumed they'd just use the gov't mandated encryption backdoor.

Then again, since the master code was 000000, it wouldn't really be to difficult to break without a backdoor

Okay, but if they can do that to our networks, why assume they can't about as easily do it to us?

> People assume this and I never understand why

There's at least one science fiction writer who had similar thoughts and wrote a story [1] where the FTL is pretty much the only technology in which the FTL aliens who visit Earth are ahead of us.

https://en.wikipedia.org/wiki/The_Road_Not_Taken_(short_stor...

There's a good deal of Turtledove in my perspective on this, yeah. His academic study of history lends a perspective few if any other authors in my experience share; my own study of the same subject, though entirely amateur, tends to make his counterfactuals seem more plausible rather than less, by which I infer both they and their consequences in his stories are drawn with scholarly care.

> People assume this and I never understand why.

Of course it is not a guarantee. It is possible that the alien invasion fleet arrives, they land, unload their main battle tanks and a passing puppy laps up their whole fleet accidentally.

What we know that by virtue of them being here they are either very good at faster than light travel, or they are good at traveling slow.

If they are good at FTL what else are they good at? We currently think that is impossible. What other things we think as impossible are practiced by them?

If they traveled slow, they must be also good at maintaining their equipment on crazy long timeframes. It also shows that they are the patient sorts who plan and execute things on the order of timelines our empires crumble. How long have they been with us then? How much preparation did they do beforehand? Did Pham Nuwen code the intel management engine?

But sure, it is possible that the Aliens arrive. They broadcast a TV signal threatening us, but unfortunately the sync is a bit off so basicaly no-one understands it. Then they enter our atmosphere. The high oxygen concentration rusts their equipment and they all die.

Seeing something occur that we thought was impossible tells us our understanding of physics is incomplete, which we already know. Seeing how it is done would probably tell us more, but we haven't. Until we do, we're guessing, and to assume FTL mastery confers godlike powers is as much an assumption as any other. Turtledove addresses this in the story that a sibling commenter mentions; I can also recommend that story, which rewards the reader with considerable entertainment while making its point about what can reasonably be assumed in the total absence of information.

The same goes for the sublight option, only a lot more so. Unless they have FTL communications, which I believe we also consider effectively impossible, by the time they get here anything they think they know about us will be wildly outdated, in technological terms at the very least. Possibly also in terms of the dominant terrestrial species, but we can be generous here.

We can be generous about their information latency because that only matters if they want it to. Any species which wants us dead and doesn't care what state the planet's left in - a reasonable assumption, if we're talking about them popping our nukes at us - doesn't need to come close to landing, or even to orbit, to do it; a kinetic bombardment in passing will amply suffice to depopulate Earth to more or less any degree desired. For subluminal interstellar travel to be even remotely feasible, even for an individually long-lived species, implies access to the kind of delta-V budget where the only limiting factor in such a bombardment is the time it takes to accelerate impactors, which may be zero if those are released before or during deceleration to match velocity with our solar system.

In the former or FTL case, we don't know how FTL works or even could, and we therefore can assume anything we like - with all assumptions at equal risk of bankruptcy. In the latter or high-sublight case, they don't need to be more clever to kill us if that's all they're after, and it may be unreasonably charitable to assume we would even get a chance to see it coming.

The state actor would probably assume a surreptitiously placed space-borne nuke, like on a "space telescope" or other larger satellite.

You don't need all that fuel to get it into space, it's already there. You just drop the warhead.

To deorbit things requires delta-v, not “just drop it”.

If they entered the atmosphere stealthily and launched from sea level, then it would appear to be similar to a submarine launched missile.

> It would be obvious if a strike came from an extraterrestrial source, there would be no terrestrial launch detection.

There would be no launch detected, that is true. That doesn’t mean that it would be obvious that the attack was extraterestrial. The alternative hypothesis would be the that the known terrestrial enemies developed some technique to confuse your sensors, or cloak themselves, or bribe your watchdogs, or pre-position warheads in space, or any other similar deception. People would be sooner thinking that their enemies smuggled nukes in overland than to think that aliens attacked them.

> A lot of effort is currently put into tracking missile launches and predicting ballistic trajectories. The goal is to give some warning if a nuclear strike is launched.

Less than advanced nations such as North Korea and Pakistan have nukes. Do you think that their monitoring systems are really that good?

No, but they won't destroy the earth with what they have - untold destruction of couple other nations, with millions dead and extreme humanitarian and economic catastrophe - sure, but not extinction of life on earth.

Yeah that's true, I just worry that things could escalate quickly once there is any exchange of nuclear weapons. It would certainly be destabilizing to a great extent.

My concern is that it would possibly snowball and draw in other actors.

To expand on my previous comment, one of the routes to armageddon that I have been imagining for years is something along the lines of:

1) A surprise meteor hits Pyongyang or Islamabad.

2) Their military hits their preprogrammed nuclear targets.

3) This draws larger powers into a nuclear exchange.

4) Fin.

But really, I think a bioweapon made by some kid in >2070 is probably more likely.

I don't see why or how the step 3 would happen. Even if NK nuked South Korea, and even if theoretically US responded with a nuclear strike(and that is already really stretching it), why would other superpowers respond with their own nuclear strikes? China would be super unhappy, sure, but would they attack US with nukes over destruction of North Korea? I don't see it.

I can see Pakistan and India exchanging nukes, but why would anyone join in that?

NK nukes SK, USA nukes NK, CCP needs to show that they are not weak and nukes something America-adjacent (ex: Guam). I think all bets are off at that point.

There is a contingent of generals in every nuclear capable country which is itching to use them. Historically, it has only been a rational civilian leader who has kept them in check.

There was recently a US President who was talking about nuking a hurricane.[0] Once nuclear weapons are in play, we just need one irrational reactionary leader, in the wrong place, at the wrong time, and Fin.

[0] https://www.washingtonpost.com/weather/2020/06/08/new-bill-w...