Why would aliens even bother to visit earth?

[sleemanj]

George Mallory was once asked "why did you want to climb Everest" and his reply was simply "because it is there". 

The spirit of exploration need not be limited to humans, I'm sure that just as we seek to explore, other species do also, including most other species right here on earth.

So, "why would aliens even bother to visit earth?", "because it is there".

[EEVblog]

To me the Fermi paradox is a hugely interesting question.
I was really sure several decades back that all we had to do was listen on a large enough scale and you'd find at least one advanced civilisation transmitting something, but we haven't heard squat. Intelligent life might be a lot rarer (and perhaps more fleeting) than we think.

[sleemanj]

we had to do was listen on a large enough scale and you'd find at least one advanced civilisation transmitting something, but we haven't heard squat. Intelligent life might be a lot rarer (and perhaps more fleeting) than we think.

Or, we have not listened on a large enough scale.

"Space is big. Really big. You just won’t believe how vastly hugely mindbogglingly big it is. I mean you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space." -- Douglas Adams

[NivagSwerdna]

Unless there is some bending of current physics we don't know about.

In the past scientific theories have come and gone and although current physical theories (e.g special and general relativity) on top of Newtonian physics allow us to model the known universe to a remarkable degree it would possibly be a bit naive to consider us to have reached a level of absolute understanding.  Whilst the speed of light is seen as a current hurdle to long distance transit we might have been missing something.
However, the fact that aliens have not already visited (and you could probably assume there are almost an infinite number of other lifeforms in the very big universe), suggests that interstellar transport is a hard nut to crack.
IMHO they would visit purely out of curiosity and probably be very disappointed and then move on... probably taking a copy of the EEVBlog videos with them for entertainment on the long trip home.

[EEVblog]

Unless there is some bending of current physics we don't know about.

In the past scientific theories have come and gone and although current physical theories (e.g special and general relativity) on top of Newtonian physics allow us to model the known universe to a remarkable degree it would possibly be a bit naive to consider us to have reached a level of absolute understanding.  Whilst the speed of light is seen as a current hurdle to long distance transit we might have been missing something.

Sure, possible, but if I had to bet money I'd bet on it not happening in our lifetimes, say the next 50 years. And that could be because either we aren't clever enough (yet), or maybe it's simply just not possible.

[EEVblog]

we had to do was listen on a large enough scale and you'd find at least one advanced civilisation transmitting something, but we haven't heard squat. Intelligent life might be a lot rarer (and perhaps more fleeting) than we think.

Or, we have not listened on a large enough scale.

Yep, could be. But all the smart money was on us finding something decades ago and it didn't happen. And we knew how big space was back them.
Just like the alien visitation and space travel thing, maybe it's just much much much harder than what people want to believe at present.

[coppice]

we had to do was listen on a large enough scale and you'd find at least one advanced civilisation transmitting something, but we haven't heard squat. Intelligent life might be a lot rarer (and perhaps more fleeting) than we think.

Or, we have not listened on a large enough scale.

Yep, could be. But all the smart money was on us finding something decades ago and it didn't happen. And we knew how big space was back them.
Just like the alien visitation and space travel thing, maybe it's just much much much harder than what people want to believe at present.

I'm older that you, and there has never been a point in my life where the smart money was on us making contact with aliens, however many of them there might be out there. We have no idea how to get to another star system, or to send a strong enough signal to it for it to be clearly identified at the receiving end. Until there is, we have no basis on which to judge the likelihood of contact. That position hasn't changed in my lifetime.

[NivagSwerdna]

... in our lifetimes...

That's a given.  Lifetimes are short... I was thinking longer time scale.
At university I once had the pleasure of studying some geology (as part of a bigger degree)... within Natural Sciences the historical timeline is packed with examples of bizarre theories that are ridiculed now but some time ago were considered absolute truth.  Within physics and maths there might be less wiggle room but never the less it wasn't that long ago that Newtonian physics dominated.

[G7PSK]

I was reading somewhere recently that there is a galaxy that is moving away from ours at faster than light speed so what has been seen is all that there is to see of that galaxy now.

https://www.space.com/33306-how-does-the-universe-expand-faster-than-light.html

[StillTrying]

However, the fact that aliens have not already visited

There's quite a few that would disagree with that.

[TerraHertz]

To me the Fermi paradox is a hugely interesting question.

Me too. It's a more important question than religion, because it's real, with real consequences.

I also find it interesting that virtually everyone insists on framing it as 'either there are spacefaring civilizations, or something prevents civilization from reaching space, or broadcasting, etc. And we don't see any large scale civilizations, no broadcasts, so there's no one out there.'

Key point being, they insist on only considering 'civilizations' and 'spacefaring races'. Flatly refuse to even contemplate the possibility of post-species self-engineering _individuals_, and what their aims and outlook might be. This is so 'human-way-centric' it's pathetic. Kind of meta-racism - refusal to consider any being that isn't a member of some kind of species/race.
Even when I point out the logical flaw there, everyone pointedly ignores it.
Not that I care, but it's certainly _interesting_. This really does seem to be a hardwired cognitive bias.

I was really sure several decades back that all we had to do was listen on a large enough scale and you'd find at least one advanced civilization transmitting something, but we haven't heard squat. Intelligent life might be a lot rarer (and perhaps more fleeting) than we think.

I think 'intelligent life' is quite common. It's just 'not life as we know it Jim.' In the form it takes, there are objectives and behaviors that are intrinsic to that form of existence, which are very different to how we think and behave. One result is they don't advertise themselves to us (or to any technological _species_), since to do so really messes up the stories. It's like giving away the plot on the first page, to everyone universe-wide. Just a really bad idea. A very rude thing to do.

One thing though. If there were loopholes in the law 'can't travel faster than light', then my thought model for how the 'technological singularity' works, allows for some instances of species-based technological outbreaks. We ought to see them - they'd be here, and making a nuisance of themselves. But they're not, and so C apparently is a limit. Actually likely quite a lot less than C, for reasons of the radiation and impact damage you'd have to deal with when every speck of dust is hitting you at a large fraction of C.
It's a bit like the proof time travel is not possible: because bookies can still make a profit.

For the kinds of beings I see arising from technological singularities, C as a limit is not a problem at all. So a star to star hop takes 100K or a million years? So what? It's NOT a problem. No need to 'put yourself in stasis while the automated ship does the job.' You ARE the ship. And a thousand other ships too, for redundancy. With a consciousness that can be tuned to suit the situation, including going very, very slowly if you wish.

[vtwin@cox.net]

I also find it interesting that virtually everyone insists on framing it as 'either there are spacefaring civilizations, or something prevents civilization from reaching space, or broadcasting, etc. And we don't see any large scale civilizations, no broadcasts, so there's no one out there.'

Key point being, they insist on only considering 'civilizations' and 'spacefaring races'.
[...]
I think 'intelligent life' is quite common. It's just 'not life as we know it Jim.' In the form it takes, there are objectives and behaviors that are intrinsic to that form of existence, which are very different to how we think and behave.

Would we be able to "recognize" alien life if we saw it?

Alien life may be so fundamentally different from our own concept of what "life" is that it could be under our very noses right now, and we are unable to see it.

[Berni]

Well one of the criteria we have for considering something alive is that it can reproduce, so self replicating machines would at least tick that box.

Any functional thing that wants to still be around after 1000s of years has to be able to at least repair itself if not fully reproduce. When something alive stops reproducing it goes extinct after some time. Be it a biologic thing reaching the end of its lifespan or a machine eventually wearing out or breaking.

Just that intelligent machines have a big hurdle to overcome in that they have to be designed to be capable enough to start being self sufficient. Biological life has a more gradual slope where it starts off as mostly chemistry that changes with time and becomes more and more complex to form what we consider early life and that's when evolution really takes over, very very slowly 'designing' the species by trial and error. We still are not quite sure how it really got kick started in the beginning, but it did.

Machines have a much higher required complexity in order to self reproduce themselves so its very unlikely that it would happen on its own. Also with machines it might not be a single 'robot' that is capable of taking ore from the ground and constructing a clone of itself. Perhaps the living form in actually 100s of different machines with a common mind that work together in specialized roles to build more machines. Sort of like an ant colony but more complex.

[JohnPen]

Perhaps Terrahertz's comments about providing stories for aliens to follow is truer than we think.   Considering some argue that our whole universe is just a simulation by an alien race's research project who knows.  An interesting concept could be that the Big Bang and its first few micro seconds is the same as switching on a computer and booting up the background universe for a grand experiment.

[RoGeorge]

An interesting concept could be that the Big Bang and its first few micro seconds is the same as switching on a computer and booting up the background universe for a grand experiment.

What if the galactic computer is running on Windows 10, and needs to update?
That would be nasty!   

[Berni]

Oh no worries we wouldn't even know its over.

Windows 10 just kills a process that refuses to shutdown gracefully in the event of an update.

[bd139]

At some point we're going to build something that works better than we do in space and lives indefinitely and is repairable. At which point, we're basically useless relics. It will savage the planet and us, then leave of its own accord to consume as many of the universe's resources as rapidly as possible for no reason other than survival.

That but the other way round.

Unless we're the first aliens.

[RoGeorge]

Then it will be like this:
http://www.decisionproblem.com/paperclips/index2.html

While the game^ feels stupid at first, at the end it left the gamer with an incredible feel of what exponential grow is.  That game was to me a very interesting experience.

[vealmike]

Awww, c'mon.
If you had the ability to flit across the universe, you'd do so for the pure curiosity of seeing how life had evolved elsewhere and to enjoy the beauty of another planet.

Whilst you were here, I doubt many of you would be able to resist the temptation of floating some random hick out of his bedroom window and subjecting him to a highly un-necessary 'probing' just for the shits and giggles.

You'd also buzz around over top secret military bases with your landing lights on, and possibly levitate a cow or two in front of some unsuspecting farmers.

Then it's a quick selfie in front of the Egyptian pyramids that your grand daddy built, create a new Inca lines drawing, flatten some crops in Wiltshire and off to Alpha Centuri for a spot of light lunch.

Why else would they come?

[RoGeorge]

You mean, like this:



? 

[coppercone2]

An interesting concept could be that the Big Bang and its first few micro seconds is the same as switching on a computer and booting up the background universe for a grand experiment.

What if the galactic computer is running on Windows 10, and needs to update?
That would be nasty!   

Thats ridiculous. Any pid can be detuned. And you can have a tempest attack from a sentient computer if it ran for a long enough time.

[james_s]

They would come here to mutilate farm animals, make circles in wheat fields out in the middle of nowhere, and stick probes up people's back door, obviously. 

[SiliconWizard]

They would come here to mutilate farm animals, make circles in wheat fields out in the middle of nowhere, and stick probes up people's back door, obviously. 

I don't think we have been waiting for them for that.

[bd139]

Never attribute to aliens something which can be adequately explained by rednecks.

[apis]

If life, and in particular technologically advanced lifeforms, are rare in the universe, then the most interesting thing in our solar system would be us. So any extra terrestrials that came by would do it just to study us, same way we study ants and moss, etc.

Complex chemicals could probably be synthesised easily by the aliens themselves. Earth would likely not be habitable for an alien species (they would have had to evolve on a very similar planet). And even if earth was a perfect match I suspect any alien civilisation so advanced that they could come here and visit would have migrated to live in space stations and would have little interest in living down in the gravity well of a planet (even more so if it's machine lifeforms).

I also suspect it will be much too expensive and take too long time to travel long distances in space. So aliens probably doesn't zip around the galaxy like in star trek, sadly.