Unless you consider that they might have the technology to reform matter how they wanted out of other atoms. It might not be worth the hassle to invade a planet for resources that you don't need.

What do you mean by THOSE species?!?!?!

You have something against us?

1) Aliens are from a competing biosphere. The only interaction likely between us and them is one of competition.
Its smart to kill us before the resource wars start. Evolution has everything to do with it as a major part of evolution is competition for resources. Humans are of the same biosphere as other humans and of the same species as well as being a social species. The anology you make in point 'second' is erroneous.

2) Name one indeginous culture that isnt irrevocably altered and brought to the brink of destruction by the arrival of more powerful and more advanced cultures. You cant, never happened. The cultures you linked are all endangered, marginalised and until recently and sometimes even today, persecuted.

3) When one travels faster then light one leaves a wake visible in normal space. It travels at lightspeed. This is an effect of physics that is often described by the more intelligent sf writer, i.e. the ones with a science degree or those who do research, such as Stephen Baxter, Dan Simmons or Larry Niven. If I could figure out the name Id print it here, and if I feel like it Ill do some extensive googling/ leafing through my books to find it. I must say however that I do not like your tone one bit, so I probably will not bother. Though I believe mr. Simmons calls it the Hawking effect. This is real world physics, and sound.

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It should in fact be quite easy and cheap to scour the galaxy for alien life and then destroy it.
All you need is one von Neumann machine. This is a device that self replicates.
I believe it has been calculated that one of those machines can span the galaxy in a ridiculously short time, in the order of thousands of years. All for the relatively low cost of one machine.
Killing aliens is also not a problem. One may reasonably assume they all need their sun.
Alter it to emit more radioactivity.
Politically I dont think this would present much trouble at all, though I can only take human psychology into account. But I believe that it is perfectly possible to get humans to vote for the construction of such a von Neumann machine. Its all about spin. Safeguarding the future.
Making sure they dont take the resources that belong to our children.

The fact that aliens are not here is actually an intriguing question. Fermi paradox.
It only takes one race to escape the constraints of Malthus and escape into space for them to be able to colonize it all with relative ease and speed. They have not, at least that we can detect.
Furthermore our galaxy looks like what you would expect a primordial/ pristine galaxy to look.
There are no signs of the vast engineering projects that we ourselves can already envision.
Such as artificially altering the lifespan of a star, wich would be visible in its spectrum.
No black hole constructs, nothing shaped or terraformed apparently except by nature.

Now, this is a scarier thought than aliens coming here because one begins to imagine some sort of galactic reboot that wipes em all back to the level of pondscum on a regular basis.
Maybe the answer to this paradox is more benign in that it is possible that most intelligence is trapped in a form that cannot possibly begin any kind of useful technology. Hard to discover fire underwater, hard to make tools if youre a whelk.

I dont know, but Fermi scares me more than aliens showing up on our doorstep.

This happens in Mass effect and Star Trek, but wakes would only be generated by FTL travel that still involves movement in "Real Space." They aren't generated by jump drives, hyperdrives, or 40k warp drives. But the ones that don't generate wakes are also probably the less likely ones to be possible, so it doesn't matter.


As for Von Neumann machines, such devices are a potential hazard to the creator species, especially if their ability to distinguish Friend vs. foe was damaged by reproduction error. As for the thousands of years, that's only possible if the probes have FTL themselves. It also wouldn't be the cost of "one lowly machine." It would be the costs of a massive R&D project, months of accelerated reproduction testing, and plenty of other research in order to create a Von Neumann probe that could kill a planet's worth of alien life forms, reproduce, and reproduce with resources not needed by the creator-species.

And no, killing aliens is a problem. Even if you do use Von Neumann machines you still have to design the sort of technology capable of altering stars, deal with potential political fallout, and if you don't have Von Neumann machines then it is even more of a problem.

While Von Neumann probes might seem easy in the grand scheme of things, an alien society doesn't necessarily have the political will, economic fortitude, or technological savy (ignoring the possibility of biological incapability, which you addressed when talking about the Fermi paradox) to actually build a weapon of galactic genocide.

There's no such thing as "competing biosphere(s)". Only living beings are competing against each other. And, to be completely technically exact, even that is not the case - http://www.amazon.com/Selfish-Gene-Anniversary----Introduction/dp/0199291152/ref=sr_1_1?ie=UTF8&qid=1305341022&sr=8-1 (regardless if they're the kind of genes we have, i.e. written in DNA molecules, or some other form of genes).

Also, "of the same species" is quite a fuzzy concept. Yes, biologically the term is well-defined, but one of the things which are quite counter-intuitive about the term is, e.g., if you thought that if A is "of the same species" as B and B is "of the same species" as C then A must be "of the same species" as C, you're wrong (in other words, the relation is not transitive).



"Endangered, marginalised and until recently and sometimes even today, persecuted" is a lot different than "completely destroyed in three generations".



I like my across-the-Internet feelings being mutual.

Those are all very good points.
I suppose those reproduction errors in von Neumann machines would deter all but the most xenophobic species from actually building one. I think its safe to say that any biological advanced form will be aware of how nature sometimes stumbles upon defects that are beneficial or harmless to the altered entity. Mutation is how evolution takes leaps.

I believe the calculation Stephen Baxter once made was based on current Earth technology. Solar sails and Bussard ramjets.
I would have to look up exact numbers but it was in the order of thousands of years. Maybe ten thousand, but not much more (as I recall).

I agree that building one of those things is probably unfeasable for any civilisation that isnt at least unified at the planetary level. We couldnt do it, with our 150 odd governments, that for sure, none of the nations has the economy on its own.
Hmm.

I still think destroying a species as unadvanced as to be bound to a single planet as we are is easy to destroy.
With our current level of technology we can already envision ways to alter a star, even if we do not have the economic capability or can actually manipulate electromagnetism on such a scale (yet).
Failing that, it is very easy to hurl a dozen or so dinosaur killers our way.

Youve given me a lot to think about, I like that, thanks

The galaxy is about 100,000 light years in diameter, and the numbers I've seen for Von Neumann probe spread are closer to half a million years. I'm not inclined to think that thousands of years would be possible without FTL. I'd have to see his math to change my mind on that.


While we can theorize, the problem for the alien is the practicality of it all. Launching Dinosaur killing asteroids and altering stars are much more expensive and hard to do then simply ignoring artificial radio signals. Also, let's assume for a moment Von Neumann probes have been built and sent out. Wouldn't it be more practical for an ecology of Von Neumann probes to simply build nukes? Draggin an asteroid into an impact course with a planet or altering a star would take much more energy for the probes then simply building a planet-side Von Neumann factory that mined Uranium to build nuclear weapons.

Genes arent species and its a fallacy to reduce an organism to its genes as is the trend in modern biology.
There are things that are hereditary but not genetic, such as the influence the mother has on an unborn child.

One can envision the entire biosphere of Earth as one interlocking mechanism, one vast machine.
Life changes the planet and in doing so opens niches for new life to flourish into ever increasin complexity. Spiders produce a from of organic copper that without mamallian life could not exist. Its a massive greenhouse and out of the dung of one species another rises.
Our current biosphere can be seen as a vast machine whos primary function is climate control.
There are great redundancies and balancing factors built into our biosphere to keep things stable and liveable.
Such as a bloom of algae to absorb an excess of carbon dioxide.

The central point here is that an alien Gaia is alien and is in no way compatible with ours. Compared to aliens, centipedes are our brothers.
They will be driven to spread their genes as we are ours and there can be nothing but competition when the two spheres meet.
There is such a thing as a competing biosphere if you have more than one of em.

I may be wrong in remembering numbers. It indeed doesnt make sense to traverse a 100k lightyear galaxy in under 100k years when below lightspeed.

Dinosaur killers can be sent technically almost for free.
A rocket on a comet that uses the ice or volatiles of the comet as fuel.
A movable mirror on a comet that works as a solar sail. It doesnt have to be fast an furious. A little push at the right time in the right direction is all that is needed. Dont forget, on longer timescales a tiny deflection in orbit or accelaration adds up.
This is how we can easily deflect harmful asteroids. A tiny nudge, over a long enough time.
All we need is an early enough warning.

Alright then, I do see how Asteroids could be more practical given that, but I'd still have the probes build Nukes. After all, gotta give 'em a way of fighting a species that can deal with such means of attack as redirecting big rocks.

And nobody said that genes are species. If you read the book I linked to, you'd get the idea of why genes are those who are actually competing a lot better.



And the same one can also envision the entire Universe as an interlocking mechanism, unless one's imagination selectively fails.



If you truly think that the algae absorbing carbon dioxide is a balancing factor built into the biosphere to keep things stable and liveable, you're hugely misinformed. Like every other "balancing factor", that one is a result of an accident - lifeforms which "eat" carbon dioxide and "crap" oxygen have appeared so there was excess of oxygen, and then later lifeforms appeared which "ate" this oxygen and "crapped" carbon dioxide. That's all there is to it - it's purely accidental. As with every other thing in our biosphere, the conditions aren't what they are because they're comfortable and appropriate for us and other lifeforms, but the conditions are comfortable and appropriate for us and other lifeforms because of what they are. Saying otherwise is like if water were to be poured in a cup and be surprised by how the cup adjusted itself to its shape.

Yes, its totally accidental.
There is no conscious will involved whatsoever, its just that things turned out that way because they worked.
Oh, I hope you dont think I was implying there was some sort of conscious process or some sort of plan at work here, if so then I have totally expressed myself wrongly.
I mean that in the case of increasing complexity.. once you get a lifeform with a bloodstream pretty soon you will see blood parasites. I mean that a species by its very existence and living opens up niches for other species to flourish in. Those algae arent there for the purpose of soaking up carbon dioxide, it just happens that they feed on it and that when an excess is in the atmosphere they will increase in number, so driving the co2 down.
That this works self-regulatory for the biosphere is again accidental, but it is an evolved system that means that the biosphere has buffers to absorb impacts like that.
One of my favorite quotes about this is: 'Life appears everywhere it can. Where it cannot it also appears, but it takes a little longer.' (paraphrasing)

The sellfish gene by Dawkins is actually on my 'wanna read' list, together with many others. Books I read keep referring to it.
Ill get to it eventually, but you know how it is. I still havent read Moby dike either.

That is an intersting point about seeing the galaxy as a super biosphere in wich all planetary biospheres play their part, but I think that is only possible if the panspermia theory turns out correct. This theory states that life can get a foothold somewhere through spores drifting through the interstellar medium. I think it would be very interesting to send probes to the Jovian Lagrangian points to see if and what kind of spores we can find there. Math tells us that bacteria spores at least can escape our gravity well and biology tells us that some spores at least can survive outer space.

If this theory is correct we would have a common ground with aliens.
But I believe that if life evolves independantly from each other, if each biosphere is unique, that the lack of common ground will cause great conflict when two alien biospheres meet. Its all about survival, about the propagation of one set of genes over another, but on a much larger scale than single organisms.

I don't see why there'd be a lack of common ground, except of course in the literal sense. Non-literally speaking though, I don't see why different origin would have to mean different grounds. First of all, we wouldn't explore the space to "propagate our genes", we would explore it to explore it. Second, even if it was about the propagation of genes, I don't see why the aliens' genes couldn't propagate alongside ours. The space is incredibly huge and there's space (there's a particularly stupid unintentional play on words) for us and the aliens.

Yes, we would explore it because it is there. We are humans. We climb mountains for no other reason than that they are there.
But when a buck in spring displays and fights other bucks over a doe he doesnt want to propagate his genes either.
He is following his instincts and has possibly nothing other on his mind than doing the nasty.
As a secondary effect though he sires new offspring and ensures the survival of the species. I dont think one can argue that the long term survival of deer kind is on his mind, but that is what his behaviour ensures.

I have sometimes philosophised that it is possible to see humans as the sixual organs of the biosphere.
We have the means, unique in the evolution of our planet, to actively spread the genetic code of our kind of life throughout space.
When we colonise space we wont just take humans. We will take pigs and cows and corn. And also things like cockroaches and flu.
Its not a stretch to see us as the means through wich our biosphere propagates.

To encounter another gaia is in this sense is a threat to our propagation, our survival.
When this other evolution of life is so totally alien to us that compared to them a scorpion is our brother I dont see how there could be any peaceful relation at all. I seriously doubt any communication is possible. On earth we get by with drawing circles in the sand and once the confusion that entails is cleared its plain sailing. (One rock, in addition to being a rock is also one. circles in the sand can get confusing fast.) And those are creatures that think like us.
What hope do we have of ever understanding a species that a) has type of math without integrals b ) communicates by changing colour and emitting scent (to give one of a myriad of exotic possibilities)

Best we can hope for is a grudging peace alongside each other. I dont think we can ever occupy the same space and I cant see border confilcts not happening. (How would you convey the horrors of genocide to a species that has no concept of self, for instance)

I believe that in the end we will be too alien to one another to do anything but stare at them and call em 'them'

Like lions and tigers can occupy the same territory, but never interacting. Avoiding each other while both after roughly the same resources. When things get tough or a meeting is unavoidable, its a fight.

Also: yes, space is vast but you cannot escape Malthus. Only postpone.
In the end resource scarcity is inevitable.

Aside the fact that I think there's no difference which can't be overcome, I have to point this out as the thing which just makes no sense at all. There is no "math without integrals", there is math. If a species hasn't yet come up with a concept of integrals, that has nothing to do with whether that concept is "inside" the math or not. Although frankly, if a species hasn't come up with a concept of integrals, they sure as hell won't be flying through space any time soon.

I know

To our type of understanding at least.
That is what I meant to convey, the utterly alien. A square circle.
Things that make no sense and cannot begin to, because there is no way to bridge the gap in understanding, no common ground.

As Larry Niven once said: By definition, all aliens are insane.

It was kind of meant as a point of philosophy rather than an example of actual things in reality.
How do you deal with a hive mind that has no sense of self? To whom destroying an entire fleet and fledgling colony is merely a way of saying hello, making themselves known? To them it would be like burning back some grass that encrouched on their territory. Whats the big deal, theres still lots of grass?

How do you hope to deal with a species that enters our solar system, ignores us, and starts dismanteling our jovians and arranging the remnants into to them aesthetically pleasing four dimensional poetry, because their unborn great grandchildren asked them to?

And thats just what I can come up with. The truly alien will have goals and motives inconceivable.

While to our mind you cannot construct a logical mathematical framework without integrals, who is to say an alien mind cannot?
Maybe it has a type of math that describes pi as a fixed number, rather than the ever repeating fraction our math leads to.

That is what I mean by the alien. You would have better chance of communicating with a spider, understanding what a spider wants because it is orders of magnitude closer to your way of existence than an alien.
Thats why I dont believe in the peaceful alien.

You are taking the whole "totally alien" thing way too far on too many levels. While it is not impossible that we will meet aliens which indeed are as alien as that to us, you have to understand that if an intelligent and sentient species has evolved on a planet remotely similar to ours it is certainly not going to be that alien to us. If a species evolved floating around in a gas giant, then I see how it could be that alien to us. But then again, intelligence, sentience and sapience are extremely costly things biologically speaking so those traits get positively selected only if there is a great benefit from having them and, frankly, I don't see how something floating around in a gas giant could benefit from either intelligence, sentience or sapience so much that the benefit outweighs the cost. Moreover, we don't even know whether life can originate in a gas giant's atmosphere in the first place.

True, but mind is of a higher order. Its an emergent feature.
It comes free of charge given enough complexity. There is no way to predict in what logical fashion it organises itself.
Wich is why I made the example of the hive mind, its very alien.
For a real world example immerse yourself in the way of thinking and religion of the Aztec. That is very alien and they are humans. And yet what they write makes no sense at all.
We can understand the words, but not the message.
Similar, imagine the thought processes of a 13th century shogun. The way they think, they way they have logic is surely internally consistent to them but utterly unimaginable to us.
Those are the aliens in our own species. An alien not only of a different species but of a different evolution/ biosphere is orders of magnitude more difficult to understand.
That is why I made the point of panspermia/ independant evolution. If we at least have genetics in common there is some hope of understanding each other.

Im tired now and dont think I made this point well enough
Ill look at my post tomorrow and see if I can explain myself better. Night

Oh, no no no it doesn't! Don't you know that (approx.) 25% of the oxygen you inhale is used to power the sentient machine in your head? In a great majority of situations, having less oxygen (or whatever substance the organism inhales (or whatever the verb for that is)) wasted by your brain and more of it wasted by your muscles (or whatever means of locomotion an organism has) is much more beneficial. The conditions have to be incredibly specific for evolutionary pressure to get so wildly twisted that having so much oxygen wasted by your brain so that it can be intelligent and sentient is actually beneficial, and it has to happen at a very specific and convenient time for a species to actually evolve that way, so it's a very improbable thing.

One last post before bed

I believe that in the book Godel Escher Bach, an Eternal Golden Braid the physicality, the math behind consciousness is discussed in detail.
I know at least that part of the following also comes from the excellent 'science of Discworld' books by Ian steward, Jack Cohen (yes, the Jack, who invents all those aliens for authors and hollywood) and the Terry Pratchett.
(Ian Steward himself is also a the, if for nothing else for 'the annotated flatland.)

Mind, at least from a physics perspective, seems to come free of charge once a sufficient level of compexity is reached.
It is called emergence.
I have examples involving logic circuits 'bred'' in such a way that a human engineer cannot replicate its function, of anthills and mantis shrimp but I am too tired to come up with any detail.
Ill try to look up and post details tomorrow if I can find time.

edit: example of emergence: Humans are pattern recognition machines and we are very good at it. We can recognise a tiger hidden in the shrub 9.9 times out of ten and that is very good, though we have evolved to do so.
Free of charge with the ability to recognise patterns excellently comes: The ability to see ourselves as a stable pattern. A sense of self. Wich is a feedback loop, as Simmons said, a holistic soliton.
Seeing shapes in clouds.