Hawking's aliens

It looks like there is a theme going around the science blogosphere, triggered by a few remarks from Stephen Hawking.

Stephen Hawking says we should avoid any aliens—they'll destroy us.

Sean Carroll agrees, but think it's highly unlikely.

Phil Plait disagrees that aliens will destroy us, also thinks it is unlikely anyway, but also thinks it more likely we'd be demolished by von Neumann replicators without seeing the aliens at all.

Ethan Siegel is optimistic and wants to run out waving his arms for attention. He scares me the most.

As the token biologist, I'll differ from all of them. If I were in charge of humanity's expansion into the universe, and if light-speed is the absolute limit it seems to be, I'd be sending out robot probes all right…all loaded with the biological seeds to impose human-compatible biospheres on any remotely human-compatible geospheres it encountered. It would bombard atmospheres with bacteria, sow the planet with algae, fungi, and lichens, and work its way up to grasses and trees and rodents and birds. And then it would start unspooling the stored genetic information of millions of humans into infants that would be raised onboard, educated by machines, and eventually transported onto the now hospitable planet surface to build a new technological civilization. Communication between planets would be limited and slow, and all the planning would be long-term — thousands to tens of thousands of years — so this wouldn't be so much the growth of a human empire, but an organic expansion.

I'd expect that any intelligent aliens aspiring to expand would be doing the same thing. There would be variants: maybe Phil Plait is right, and advanced alien civilization will discard biology and advance in machine mode; it may also turn out that it is easier to modify biology than planets, so my bioprobes will produce radically gene-engineered humans who don't look much like us anymore in order to more rapidly take over new worlds.

Anyway, my bet would be on interplanetary biowarfare, the slow infiltration of engineered organisms to change environments for alien compatibility. The only way we'd be able to survive is to fight them on the same ground. Don't expect alien tripods with lasers, watch out for alien viruses and bacteria turning the soil and atmosphere poisonous or unsupportive. I'd also side with the people who are arguing we ought to worry about aliens, if they exist — if they're so advanced over us that they can travel here, they aren't going to be as interested in our primitive conversations as they are in our real estate.

I also think the possibility of that happening to us is unlikely. Intelligent life with grand schemes of interstellar expansion don't seem to be evident out there, or maybe there are interesting obstacles that thwart such growth that we haven't quite discovered yet.

By the way, I also caught an episode of Hawking's Into the Universe on the Discovery Channel, the one on alien biology. I have to say I thought it was just awful, with no useful content and was merely a contrived excuse for the Discovery Channel to trot out more cgi of imagined weird animals. Biology is definitely not Hawking's strength. Maybe his other episodes on time travel and cosmology will be more thoughtful and interesting.

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Aliens with sufficient technology do not need to mine for materials, because they will be able to generate anything from the basic quantum constituents out of which are universe is made. They will have no need to colonize or take over planets. To their advanced intelligence, space and time will be a malleable playground, and a spherical piece of rock will be no different than the emptiness of space itself. We would pose no threat and they would know it.

Stephen Hawking says we should avoid any aliens—they'll destroy us.

How are we suppose to do that? It's not like they're some bumbling sitcom landlord to whom we owe last month's rent.

"Oh, shit! Aliens! Quick everybody, push the planet behind Jupiter and hope they didn't see us."

By Brownian, OM (not verified) on 27 Apr 2010 #permalink

Thanks to you I'm going to be playing Sins of a Solar Empire, while watching Independence Day and reading Samuel Youd.

By smartbrainus (not verified) on 27 Apr 2010 #permalink

The one on time travel was shown right after the one on exobiology. It was a pretty lucid explanation of the consequences of relativity - time dilation.

The part of the episode where Hawking went on about an advanced race coming here looking for resources seemed too much like bad sci-fi, especially the laugher Independence Day. All we need is a few heroes like Randy Quaid: "I'm baaaack"

By natural cynic (not verified) on 27 Apr 2010 #permalink

I'm with Ethan on this one. One of the best answers to Fermi's paradox is that intelligent life simply hasn't had enough time to develop the intelligence necessary for intergalactic space travel. If an alien race could make it to Earth they would have figured out new means to survive past their planet's resources or can turn Mars like planets into sustainable atmospheres for themselves. Just because they are vastly superior to us in technology doesn't mean they are indifferent to us. I imagine they would still be interested in our biology, history, psychology, cultures etc. I know we would be if we found another intelligent life form, inferior or otherwise.

By besserwisser (not verified) on 27 Apr 2010 #permalink

I disagree with Hawking.

If there were some alien civilization that were so advanced as to be able to extend its reach to Earth, then clearly there's not much we'd be able to do about it anyway.

Interstellar distances are simply so vast that anything that makes it here is thousands of years ahead of us technologically.

Why worry about something we can't have any control over?

By PeteGrimes (not verified) on 27 Apr 2010 #permalink

Your idea sounds like the plot of Songs of Distant Earth.

By andrewrbeck (not verified) on 27 Apr 2010 #permalink

Since we're already broadcasting to aliens with radio and TV signals, we need to send out apologies to aliens for Rush Limbaugh, Glen Beck, etc before the aliens decide the galaxy is better off without us.

We'd be like lemurs or some such thing to interstellar travelers.

We might be put into zoos, or some such thing, but they'd not consider us to be of much value as slaves, or threat as "competition."

And really, interstellar travel is likely to be expensive through all time. Earth-type exploitation is unlikely in that case. If they come, likely it will be as scientists, wanting knowledge, not materials and energy--which are likely to be much more available from places other than earth.

Glen D
http://tinyurl.com/mxaa3p

By Glen Davidson (not verified) on 27 Apr 2010 #permalink

Here's my pickle:

Either there are aliens or there aren't. On the one hand, I'm uncomfortable with the exceptionalism behind the claim that we're the only intelligent species in the universe. And on the other, I'm unwilling to posit the existence of aliens without *some* evidence.

Remember that only one out of the ten million or so species on this planet has even achieved the ability to contemplate life on another planet. As Gould has reminded us, evolution is a radically contingent process, and intelligence was not a "forced move." There are lots of ways to make a living without being human-like.

So, on the admittedly scanty evidence we have, we can conclude that even if there are aliens, it's highly unlikely they are intelligent.

"watch out for alien viruses and bacteria turning the soil and atmosphere poisonous or unsupportive"

And why would we need alien viruses and bacteria? Aren't we doing a good enough job of that already?

By mclean.malcolm (not verified) on 27 Apr 2010 #permalink

How are we suppose to do that? It's not like they're some bumbling sitcom landlord to whom we owe last month's rent.

The question is really, should we be broadcasting our existence, particularly in the form of directed radio signals.

re #1:
a spherical piece of rock will be no different than the emptiness of space itself.

I doubt that. A big chunk of mass represents a lot of energy regardless of your level of technology. The Stargate ZPM is a myth, you can't draw significant energy from the vacuum. Yes there may be lots of energy there, but it is virtual energy and the amount you can draw is limited by the uncertainty principle. I think a true galactic traveling civilization just might be like Galactus, consuming entire worlds (or even stars) to power its ships.

The terraforming idea also shows up in Zelazny's The Keys to December. A great story with a great twist at the end, even if it's also somewhat depressing.

But be careful what you say...

Someone may claim that global warming is evidence that the aliens have arrived and are using their giant lens hidden on the dark side of the moon to heat the oceans when we aren't looking.

Since we're already broadcasting to aliens with radio and TV signals, we need to send out apologies to aliens for Rush Limbaugh, Glen Beck, etc before the aliens decide the galaxy is better off without us.

I recently saw a calculation that the amount of power in all our radio and TV signals is insufficient to even carry them to Alpha-Centauri before they fade into background noise. I think it was around 1-2ly. But I agree about the apologies anyway.

besserwiser,

I imagine they would still be interested in our biology, history, psychology, cultures etc. I know we would be if we found another intelligent life form, inferior or otherwise.

How do you know? Past historical evidence doesn't seem to indicate that we have been that interested in preserving other cultures (eg pilgrims vs indians). Maybe we've changed, but I wouldn't bet on it, nor on that of Aliens coming to earth being interested in preserving human cultures.

By negentropyeater (not verified) on 27 Apr 2010 #permalink

Btw, this journal blogging a game from Galactic Civilizations is a good predictor of what may happen if quickly reproducing alien species attempt to control the galaxy...Sun nuking commences.

By smartbrainus (not verified) on 27 Apr 2010 #permalink

I'm with Phil on this one.

BTW; I take the occasion to recommend "Mundos en el Abismo"/"Hijos de la Eternidad" by Javier Redal and Juan Miguel Aguilera, the best Spanish hard SF space-opera of all time that deals with the subject (among much other) of the dangers of Von Neumann replicators. Although without the need for aliens :-)

By El Guerrero de… (not verified) on 27 Apr 2010 #permalink

I too was disappointed by the fluffiness of the two episodes I watched. It could have been interesting and educational, but it was mostly woowoo neatokeen!

Like everything else on the Discovery Channel except for Mytbusters and Drowning in the Bering Sea for Fun and Profit, Hawking's program relied too heavily on special effects and way-out-there speculation at the expense of real science.

The Dislobbery Channel is not about selling us science for the cost of watching some commercials. It is about selling us to the producers of commercials at the cost of having to make some programs that barely pass as science.

I'm going back to Nova and Scientific American (which have both become rather fluffy of late).

By Timberwoof (not verified) on 27 Apr 2010 #permalink

Taking off from what Hawking said, whatever transmissible biologically hazardous organisms the sentient aliens might be carrying, their lack of respect for human culture, or being enslaved or conquered are just the tip of the iceberg of how first contact could go badly for us. What if the aliens are just hungry from a long space flight and see terrestrial life as an easy snack? Earth could become their latest pit stop on an interstellar highway. Despite the danger, I have never been one to let sleeping dogs lie, so I say let's make first contact and find out.

By aratina cage (not verified) on 27 Apr 2010 #permalink

So, on the admittedly scanty evidence we have, we can conclude that even if there are aliens, it's highly unlikely they are intelligent.

No? The chance that any one alien species is intelligent is definitely very, very small. However, there are lots and lots and LOTS of stars, and each of those has a chance to be the sun for a "habitable" planet, and each of those habitable planets has a (admittedly pretty small) chance of harboring intelligent life. And, given infinite chances, every eventuality will occur.

I'd be much more surprised if there was, in fact, no other intelligent life in the universe.

...we need to send out apologies to aliens for Rush Limbaugh, Glen Beck, etc before the aliens decide the galaxy is better off without us.

We actually have done worse. See the pictures that were sent back to earth in the movie Contact.

I don't think that if any aliens are coming our way, they would have any difficulty in communicating with us. They would have a lot of material to gather context and meaning from our broadcasts.

And remember the Prime Directive, even though it was so commonly breached. Any civilization that would be advanced enough to contact us would probably have to be socially evolved enough to be very careful with their interactions with other life forms.

By natural cynic (not verified) on 27 Apr 2010 #permalink

We might be put into zoos, or some such thing, but they'd not consider us to be of much value as slaves, or threat as "competition."

Let's hope so.

"All right. How 'bout this one: let's say you're abducted by aliens."
"Fine."
"They haul you aboard the mothership, take you back to their planet as a curiosity. Now: would you rather be in their zoo, or their circus?"
"I gotta go zoo. I feel like I could set more of my own schedule."
"But in the circus you get to ride around in the train, see the whole planet!"
"I'm wearin' a little hat, I'm jumpin' through fire...They're puttin' their little alien heads in my mouth."
"At least it's show business."
"But in the zoo, you know, they might, put a woman in there with me to uh...you know, get me to mate."
"What if she's got no interest in you?"
"Well then I'm pretty much where I am now. At least I got to take a ride on a spaceship."

By Brownian, OM (not verified) on 27 Apr 2010 #permalink

The argument that "If they're so advanced they'll squash us like bugs!" doesn't really ring true to me. Let's say we discovered (the equivalent of) small multicellular organisms swimming around in the oceans of Europa, for example. Would we really say, "Oh, awesome! Europa can support life, so now all we have to do is kill or enslave all of these animals..." No. We'd probably dissect a bunch, sure... So that might be a possible negative outcome if, hypothetically, an alien species had some sort of "super-sapience" that made our level of sapience seem irrelevant to them. But extermination? Probably unlikely.

As far as the apparent lack of species with "interstellar expansion plans"... If our technological arc is anywhere near typical, the period of time when a civilization's day-to-day RF emissions would be visible from any appreciable distance is vanishingly small. Already, as we move to digital transmission and the use of low-powered local transmission for the wireless hop (with wired fiber channels for all the big stuff) it is looking like our radio signature may soon be on its way out. That leaves Active SETI-type programs. And if we assume other civilizations make that as much of a priority as we do (i.e. not much), even if the galaxy were teeming with intelligent life, it could be millenia before anybody would happen to point their transmission at the right star.

If we also assume that FTL travel really is impossible -- which seems not unlikely at this point -- then galactic empires are not a realistic possibility. Occasional radio contact seems plausible, and if the concentration of sapient life is dense enough it may even be possible for a couple of species here and there to make physical contact. But unless we're REALLY missing something big in terms of physics, any sort of galaxy-spanning community seems highly implausible.

(I also don't rule out the Rare Earth -- or even Unique Earth -- hypothesis. Though the anthropic principle is a deeply unsatisfying explanation for how such apparently astronomical odds could have been defied, it's a possibility that can't be ruled out unless/until some contact is made.)

By James Sweet (not verified) on 27 Apr 2010 #permalink

Remember that only one out of the ten million or so species on this planet has even achieved the ability to contemplate life on another planet.

And all they do is jump through hoops and do tricks in exchange for fish.

The thing is, when you look at the history of planet Earth you see that while complex, macroscopic life has existed for hundreds of millions of years, technology-using* life has been around for a much shorter stretch of time.

It therefore stands to reason that, if Earth's development is a fairly typical model of how life would develop on other planets, the number of planets with complex biospheres but without a technology-using life form would outnumber the ones with a technology-using life form by an enormous margin. Therefore, if the aliens are only interested in our resources then they'd have a lot of other planets to choose from; planets who's inhabitants haven't figured out how to build nuclear weapons.

A lot of this speculation also seems to assume that the rate of technological advance that we've experienced for the past two centuries or so is a constant, when that's not necessarily true. Most of our recent advances have been driven by our unlocking new areas of physics that had been heretofore undiscovered, but there comes a point when there just isn't anything more to unlock, at which point technology will reach a plateau and we'll only be able to make small refinements to what we already have rather than the constant chain of forward leaps that we've grown accustomed to. The aliens will be working under the same laws of physics that we will, and will be limited by the same physical laws. Even millions of years of technological development isn't going to let them do the impossible, and it may turn out that we're more evenly matched with them than we think.

@negentropyeater

Past historical evidence doesn't seem to indicate that we have been that interested in preserving other cultures (eg pilgrims vs indians).

I've been reading too much of Banks' Culture series; I read that as Pilgrims vs Idirans and thought "Well, that wouldn't last long..."

By edmangoodrich (not verified) on 27 Apr 2010 #permalink

I have to say I thought it was just awful, with no useful content and was merely a contrived excuse for the Discovery Channel to trot out more cgi of imagined weird animals.

This is true of most Discovery Channel stuff, again with the exception of Mythbusters. I use a lot of NOVA and some NatGeo documentaries as (a small part of) homeschool science, but even my kids recognized at 10 or 11 that Discovery Channel was overdramatized fluff marketed to a really low lowest common denominator. (OK, I know this is sort of redundant.)

Mythbusters is a great show for teaching kids how the scientific method actually works, not to mention some actual physics, chemistry, statistics, etc. Plus Adam Savage and Grant Imahara are eye-candy for nerd women.

Forgot to add the footnote to my last post:

* technology-using life in this case being defined as a life-form with the ability to both fashion and use tools and the ability to use those tools to create additional tools of increasing complexity.

I hate to burst people's bubbles here, but:

1)Every indication is that the speed of light is in fact the universal speed limit. This means that to travel to the nearest star would take more than 8.5 years at the minimum. Travel to the nearest habitable planet is probably on the order of centuries.

2)Galactic cosmic radiation would cut our DNA to ribbons in that time, and we cannot reasonably shield against it (14 cm of aluminum would only cut it down by a factor of 2).

This, unfortunately, means interstellar travel probably will not happen. On the plus side, it means that our own unique brand of human stupidity is effectively quarantined and so unlikely to be inflicted on the galaxy as a whole.

By a_ray_in_dilbe… (not verified) on 27 Apr 2010 #permalink

I am watching "V". I remember watching V with my parents years and years ago. Although the new spinoff has not identified what these 'new' aliens want it has been clearly implied there intentions are not in the best interest of humans.

The whole looking for and inviting aliens to live with or near us kinda spooks me. Now with the new brief Hawk comments they seem slightly justified.

:\

By Anti_Theist-317 (not verified) on 27 Apr 2010 #permalink

There was a SciFi short story quite awhile back that described PZ’s colonization scenario almost exactly. Ships were to carry plant seeds, human and other animal embryos in stasis to far away planets. Once landing on a suitable world, robots would re-animate the embryos and raise the humans and everything else. In the planning stages of this venture, there was discussion of whether or not to include religious literature (bibles, etc.) in the educational materials for the yet-to-be population. An extensive study was conducted using computer models of human history and the influence of religion in that regard. The results of the study showed that without religion, exactly as many bad things happened as good. With religion as an historical parameter however, many more bad things occurred in the various world societies.
It was decided that in the interest of future humanity all religious reference to historical studies be omitted.
I suppose, under the circumstances, what they wouldn’t know wouldn’t hurt them.

@KOPD -You win the thread. XD

#30:

1)Every indication is that the speed of light is in fact the universal speed limit. This means that to travel to the nearest star would take more than 8.5 years at the minimum. Travel to the nearest habitable planet is probably on the order of centuries.

But if you are able to accelerate to relativistic speeds, time dilation means that you could travel to the stars in a surprisingly short time, subjectively. But the same dilation effect makes returning home problematic, unless you want to gamble on the far future. Still, it's an adventure, isn't it? If you were to ask for volunteers among a random sample of humans, explaining that they'll be the first people to the stars, but that they can never return unless it's thousands or even millions of years hence, I suspect a few would jump at the chance.

2)Galactic cosmic radiation would cut our DNA to ribbons in that time, and we cannot reasonably shield against it (14 cm of aluminum would only cut it down by a factor of 2).

This is why you don't send squishy meat, but wait until you're able to send some form of intelligent machines: either HAL, or uploaded intelligence. This also solves problem (1).

I'm rather surprised at PZ's attitude here. If there is life on other planets, wouldn't it be far more interesting/educational/valuable to science to study its biochemistry than to poison it and replace it with terrestrial life?

By NitricAcid (not verified) on 27 Apr 2010 #permalink

"And then it would start unspooling the stored genetic information of millions of humans into infants that would be raised onboard, educated by machines, and eventually transported onto the now hospitable planet surface to build a new technological civilization." This is an appalling idea, enslaving children with absolutely zero choice to do your exploring

By briclondon (not verified) on 27 Apr 2010 #permalink

SteveM #13?

I think a true galactic traveling civilization just might be like Galactus, consuming entire worlds (or even stars) to power its ships.

So, you're an alien intelligence hungry for resources. For some reason, rather than heading towards the core, you decide to come here. Okay, fair enough, you're already low on gas. And then, having traveled numerous light years to get here, you decide to mine not one of the gas giants, not Venus with its rich atmosphere (although maybe you can be forgiven there), not Mars, not Mercury, not one of the various moons floating about, not the giant fucking fusion furnace in the center, but? Earth.

Because? why? Earth has vast supplies of vespene gas?

By black.iris.dancer (not verified) on 27 Apr 2010 #permalink

I'm unconvinced that just because they're more advanced they'll give us the Lysol wipe treatment. Assuming they didn't discover some cosmic ethical harmony and way for everyone to live together in harmony, wouldn't they at worst think of us the way we think of chimps and dolphins?

By tdcourtney (not verified) on 27 Apr 2010 #permalink

Hawkings is right that native Americans' encounter with Columbus didn't work out too well; but that was between two members of the same species who occupied exactly the same ecological niches. Of course there would be competition.

I'm not convinced the same would apply with an alien species. For all we know the most advanced civilization out there is half a meter across consuming a few watts of energy - why spread yourself out further when it takes years to cross and looks just the same as anywhere else?

But if you want to pursue a biological line, the life out there is the one that has the strongest imperative to replicate - Iain Banks' "hegemonizing swarm". And not for any particular reason arising out of need; it's just that any species that does _not_ do this will loose, duh. If I was this super-duper replicator out to beat the competition anything less than light speed is just to slow. What _I_ would do is watch very closely for emerging civilizations, then beam across an intelligent computer code that when run will proceed to subvert the target and take over. If emerging civilizations are quite common this would be a speedy way of getting about.

The chance that any one alien species is intelligent is definitely very, very small. However, there are lots and lots and LOTS of stars, and each of those has a chance to be the sun for a "habitable" planet, and each of those habitable planets has a (admittedly pretty small) chance of harboring intelligent life. And, given infinite chances, every eventuality will occur.

Just plug in some conservative estimates for the terms of the Drake Equation and it seems nearly certain there are other intelligent species in the galaxy. Distance and the putative intractability of physical law are the obvious factors determining why we haven't seen evidence of any. But less appreciated, I think, is the time consideration. The galaxy is Vast, spatially and temporally. A local star-system-scale superpower could have arisen and faded away over an epic 50,000 years or so, right around the corner, "just the other day" in galactic terms, and we'd be none the wiser. Even more likely, technological species pop up all the time, quickly overpopulate and deplete whatever resources on which is based their energy regime and fade back into the twilight of pre-industrial technology for however long. So, pre-technological and post-technological species, where "technology" is defined on SETI terms, are monkeys for all intents and purposes on the galactic scale, and all such species have spent the great majority of their sentience in one or the other of those states. Only the cosmic coincidence of two technological civilizations "in bloom" at the same time relatively near each other would lead to contact of any sort.

Moggie@35,
Unfortunately, electronic and even materials are susceptible to radiation degradation at high enough doses--and for very long duration missions, the doses are quite high and impossible to shield against.

You can try to minimize risk, but this is a very difficult problem to solve. It's one reason NASA is doing lots of experiments these days with high-energy ions.

Also note that when you are traveling near the speed of light, EVERY ion is high-energy.

By a_ray_in_dilbe… (not verified) on 27 Apr 2010 #permalink

'There is even increasing recognition of a new science of extra-terrestrial life, sometimes called exobiology- a curious development in view of the fact that this "science" has yet to demonstrate that its subject matter exists! Another curious fact is that a large proportion of those now discussing this biological subject are not biologists.'
G.G. Simpson, (1964) 'The Nonprevalence of Humanoids', Science, 143, pp.769-775

End of discussion, in my opinion. See also Ernst Mayr's essay on the subject.

By nejishiki (not verified) on 27 Apr 2010 #permalink

I find it amusing how people still entertain the idea that aliens might want to enslave us. We are talking about a species capable of crossing the incredibly vast gulfs between stars in great enough numbers to pose a threat to us. And these superadvanced creatures can't come up with robotics or related tech to serve them that can rival the abilities of a stubborn, frail bipedal ape? Really?

Same goes for plundering resources for the most part: uninhabited space is full of them, in the form of easily harvested low-gravity objects no less. No need to fight of nasty alien creatures so they can be mined and then somehow lifted out of a huge gravity well to build more worldships. Earth would just be too much trouble when there are plenty of asteroids and moons, even smaller rocky planets, available.

What I could see aliens wanting is new worlds to inhabit, but that is only assuming they come up with method of interstellar travel that is safe for biological organisms. If they've already updated their bodies to far more durable synthetic forms to withstand the rigours of travel, they'll no longer be limited by bounds put up by evolution and can even give up living on planets altogether if they so choose.

I wouldn't be too worried about them giving us space smallpox either. We don't get a whole lot of diseases jumping to us from trees or fungi, and they at least share a fairly recent common ancestor with us. Alien germs would be adapted to surviving and reproducing in alien bodies, not ours.

By Sclerophanax (not verified) on 27 Apr 2010 #permalink

My guess as to what the aliens would want from us, assuming they want anything at all other than our real estate is this: They won't want us for slaves-we'd be far more trouble than we're worth or dinner-what's the chances we wouldn't be poisonous? No, what any advanced civilization would want out of our technically backwards one is...disertation subjects! I expect every culture on Earth to have its own PhD student. Hope we're interesting enough to preserve as a curiosity when the real estate starts running out or they discover the dilithium deposits in the mantle...

So to those in the know, is it actually possible to quantify the probability of life (let alone intelligent life) forming on any given planet? It always seems to me that maybe the ID folks have a point when they tell us how incredibly unlikely it seems for life to arise by random chance. Of course it's unlikely, but the number of planets in the Universe makes that unlikely individual event a lot more likely to occur at least once. But is it really likely to occur more than once? Seems to me that any talk of the likelihood of alien civilizations is pure conjecture, it's not something we can actually measure. We're just assuming that as small as the likelihood of life on any given planet is, there are so many planets that more than ours must have life, but isn't it possible that the probability is so small that we really are the only ones? Or is there actually some way of quantifying the probability and we actually can state with some statistical certainty that life on other planets is to be expected?

By Gus Snarp (not verified) on 27 Apr 2010 #permalink

Locutus of Gay, tertiary adjunct of Pharyngumatrix 001 reporting for assignment. The planetoids will adapt to service us.

By Josh, Official… (not verified) on 27 Apr 2010 #permalink

black.iris.dancer wrote:

So, you're an alien intelligence hungry for resources. For some reason, rather than heading towards the core, you decide to come here.

Due to the intergalactic shortage of Trophy Wives.

By Dark Matter (not verified) on 27 Apr 2010 #permalink

Nice point, a_ray, but is radiation such a problem in interstellar space? I don't know, is why I'm asking.

By daninorlando (not verified) on 27 Apr 2010 #permalink

We might be put into zoos, or some such thing,

Ok,now I've got an excuse to ask people here about this silly scenario I made up for I've forgotten what reason a while ago...

Scenario 1: The aliens show up on the planet looking for animals for their zoo. Since humans are sentient, they attempt to recruit volunteers rather than just using the stunner or whatever. For whatever reason they ask you if you want to go. If you say no they'll shrug (or equivalent gesture) and ask someone else. The advantage of agreeing is that you'll likely live about twice as long as you would on earth*. You can assume that the zoo is more of the Bronx zoo WWF approved variety than the 19th century bare cage model and that the aliens really are interested in making life comfortable. But changing your mind later is probably not an option. Do you do it?

Scenario 2: Too bad about that "no", if you said no, because you're already in it. We call it "earth". So...one day you find an alien spacecraft. You can, with some work, figure out how it operates well enough to get away from earth and get yourself thoroughly lost in the universe. You have no chance of figuring out how to use the navigation equipment. In short, you can leave but it'll be permanent. You'll only have the resources you manage to take with you. If you get seriously ill, that's probably that. In short, you'll probably not live all that long, compared to how long you'd live if you stayed on earth and you might never see anything but empty space. Do you go?

*Zoo animals really do live about twice as long as animals in the wild.

I'm surprised how much press Hawking's comments have recevied, considering that he's rehashing an argument that anthropologist Jared Diamond made several years ago (http://www.independent.co.uk/opinion/commentators/meet-the-neighbours-i…).

Diamond largely bases his case upon the way that Europeans treated Native Americans, who were in essence a primitive alien civilization (from the point of view of the conquerer). Also, since both civilizations had independently developed similar dysfunctions (like religion, despotism, and resource competition), Diamond holds out little hope that an alien civilization would be much different.

I would like to think he's wrong, but since I accept the fact of evolution, it follows that any alien life would have developed in an environment of resource scarcity and selective pressure, just like us, so it seems like special pleading to believe that aliens would be more altruistic than we are. Maybe the aliens would eventually overcome their baser instincts, but I for one am glad that the apparent universal speed limit has kept us from testing this proposition further.

A Spacefaring civilization might not have need of planets.

Our distant ancestors lived in caves, but today, 'no thanks!'.

Aliens might have the same feeling about living on a planetary surface.

Space habitats (Giant Space Stations) with nearly unlimited energy
(Hydrogen Fusion or, with a better understanding
of particle physics, Matter Conversion.)
would have 99% or better recycling.
What matter they would need is available from the exosolar equivalents to the Ort cloud or Asteroid Belt.

The only thing earth has valuable enough to ship between the stars is information.

We'll have to be careful some alien huckster doesn't trade a digital copy of earth's libraries for Cheap n Easy energy machines.

By jsl151850b (not verified) on 27 Apr 2010 #permalink

Why would you take Steven Hawking's advice on interpecies relations? Is there something he is trying to say?

By daninorlando (not verified) on 27 Apr 2010 #permalink

black.iris.dancer:

They will, of course, be coming for our oil.

By Simon Kongshøj (not verified) on 27 Apr 2010 #permalink

They will, of course, be coming for our oil.

And our jobs. Derk -uh DURR!!!

By Josh, Official… (not verified) on 27 Apr 2010 #permalink

Everyone is making the same ridiculous assumption: that alien technology is somewhat similar to our own. I don't think that people fully appreciate how incredibly, vastly, mind-bogglingly advanced alien technology would be if they were able to contact us.

Let's put this in perspective: The universe is roughly 14 billion years old. Granted, the first few billion years would have been uninhabitable to any form of life due to the chaotic nature of mature, so stability of any form was more or less out of the question. But let's say 10 billion years.

Life on earth started about 4 billion years ago. We have only just begun to use "technology"--that is, improve upon tools in a rational manner in order to facilitate the human endeavor, be it computing, building structures, transportation, etc. This is within 1,000 years. 1000/4 billion = 0.00000025% of the time. What is the likelihood that, in the 10 billion years of the universe, aliens began using technology (assuming they progress at roughly the same rate as us, which is a pretty terrible assumption itself) during the same period of about 1,000 years? It's about half as likely. In other words, it might as well be zero.

We will not recognize our own civilization in 1,000 years--and that's only 1,000 years! The chances that alien's technology is within 1,000 years of our own is virtually zero. We'd probably have to go up to something like a hundred million years before the chance became even 1%. Therefore, the technology is almost definitely MILLIONS OF YEARS AHEAD OF US.

Our brains cannot comprehend such technology. Terraforming will be meaningless; biology will be meaningless; information will be meaningless; the ability to manipulate spacetime will be (to within the physical laws) meaningless. They will most likely not even have physical bodies, and exist in some metaphysical state where spacetime is simply a medium to do whatever they do at that point. What they do is not something that we can possibly predict at all--they won't need food, oxygen, space, and the idea of death will not exist.

In other words, it's fun to discuss this, but everyone is just so off base that there's no need for concern at all.

Or is there actually some way of quantifying the probability and we actually can state with some statistical certainty that life on other planets is to be expected?

The Drake Equation is the standard attempt at quantifying the probabilities but even it is little more than an intuition pump; you get out of it what you put in in the form of your assumptions and predilections. Fun to tinker with.

Given that amino acids and other long-chain organics are commonplace in the galaxy and there seems to be no barrier to abiogenesis in the presence of liquid water and a source of metabolic energy, either chemotrophy or starlight, and given how many planetary systems we're seeing out there, life may well be very widespread indeed. But intelligent (technological, humanoid) life could still be vanishingly rare or nonexistent.

NitricAcid

I'm rather surprised at PZ's attitude here. If there is life on other planets, wouldn't it be far more interesting/educational/valuable to science to study its biochemistry than to poison it and replace it with terrestrial life?

Daniinorlando,
In interstellar space, you are mainly dealing with galactic cosmic rays. There aren't that many of them, but they are extremely energetic, making them impossible to shield against. They also obliterate DNA, since the secondary electrons knocked out of their positions by the high-energy ions have track lengths on the order of a DNA strand.

For electronics, it's probably not that bad, but keep in mind that every ion you encounter will be high energy when you are traveling at near light speed. A few years wouldn't be much of a problem--but that won't get you anywhere interesting. A few centuries...that's a problem.

By a_ray_in_dilbe… (not verified) on 27 Apr 2010 #permalink

@ #10, #45

There is actually a line of speculation around this.
It is based on one of the strangest and most fact-free publications in the serious scientific literature:
John A. Ball, 'The zoo hypothesis.'Icarus
Volume 19, Issue 3, July 1973, Pages 347-349.
which appeared in the same issue as Leslie Orgel and Francis Crick's paper on 'Directed Panspermia.'
For the record, the strangest publication in the scientific literature is the short paper in Applied Optics that proves that Heaven is Hotter than Hell.

By nejishiki (not verified) on 27 Apr 2010 #permalink

PZ,

It would bombard atmospheres with bacteria, sow the planet with algae, fungi, and lichens, and work its way up to grasses and trees and rodents and birds.

But no fishes, no cephalopods, no squid???

-DU-

By david.utidjian (not verified) on 27 Apr 2010 #permalink

If anyone is interested there is a very very good trilogy of books by Tony Ballantyne which almost is a mix between PZ's ideas and those of Phil Plait.

The first book is called Recursion followed by Capacity and Divergence. They follow a set of people across different time spans within the same universe but delving from machine (von Neumann) to computer to 'wet' life personalities in a twisting and interwoven narrative.

http://www.amazon.com/Recursion-Tony-Ballantyne/dp/0553589288/ref=ntt_a…

Check it out!

By guy.leonard (not verified) on 27 Apr 2010 #permalink

And all they do is jump through hoops and do tricks in exchange for fish.

Wait. It wasn't a double backward somersault through a hoop while whistling the star-spangled banner, was it? Because if it was, we are all screwed...

PZ,

Intelligent life with grand schemes of interstellar expansion don't seem to be evident out there...

Unless we are the evidence.

~IANVS

By The Devil's Chaplain (not verified) on 27 Apr 2010 #permalink

Should we be worried about hostile aliens? It's an interesting question.

If an alien species is so advanced that they could reach and threaten us, it doesn't seem as if they'd have any need to conquer us. Whatever they could get from Earth they could just as eaily get from a planet not inhabited by sentient life forms (unless they wanted to eat us). It also seems to me that the potential payoff of making contact with an alien civilization is great enough to outweigh any hypothetical risks.

But this is of course vry unlikely. I support efforts liek SETI but if we ever make contact it will likely be with a species who are simply too far away for us to ever meet in person, limiting communication to very long range radio messages sent and recieved at decades-long intervals.

As for the Hawking show, I can understand why PZ is dissapointed at the lack of actual science, but frankly, the CG aliens are cool so I'm happy.

By PenguinFactory (not verified) on 27 Apr 2010 #permalink

Wait. It wasn't a double backward somersault through a hoop while whistling the star-spangled banner, was it? Because if it was, we are all screwed...

I've been watching for that one and so far I think we're safe.

We will not recognize our own civilization in 1,000 years--and that's only 1,000 years!

Yeah. We could be back to fire and pointy sticks. (A fun thought experiment: could you extract the materials and then manufacture all the parts and assemble a Breeder reactor, without fossil-fuel-powered technology or any technology built in dependence on the fossil fuel energy regime?)

The chances that alien's technology is within 1,000 years of our own is virtually zero. We'd probably have to go up to something like a hundred million years before the chance became even 1%. Therefore, the technology is almost definitely MILLIONS OF YEARS AHEAD OF US.

You're forgetting Fermi's paradox. If there's a technological species that advanced that's been around that long and has expansionist or exploratory tendencies, there should be evidence. If they're homebodies, what reason is there to believe they've aggressively pushed the limits of technology generation after generation, for millions of years, even assuming that's possible? Could be they're comfortable, and see no need of the kind of vast, galaxy-spanning power that's the stuff of space opera; they're like little old ladies who only drive the Star Destroyer to the grocery store once a week and play post-scarcity bingo on tuesdays.

And then it would start unspooling the stored genetic information of millions of humans into infants that would be raised onboard, educated by machines....

All Watched Over by Machines of Loving Grace

I like to think (and
the sooner the better!)
of a cybernetic meadow
where mammals and computers
live together in mutually
programming harmony
like pure water
touching clear sky.

I like to think
(right now please!)
of a cybernetic forest
filled with pines and electronics
where deer stroll peacefully
past computers
as if they were flowers
with spinning blossoms.

I like to think
(it has to be!)
of a cybernetic ecology
where we are free of our labors
and joined back to nature,
returned to our mammal
brothers and sisters,
and all watched over
by machines of loving grace.

- Richard Brautigan

They will most likely not even have physical bodies, and exist in some metaphysical state where spacetime is simply a medium to do whatever they do at that point. What they do is not something that we can possibly predict at all--they won't need food, oxygen, space, and the idea of death will not exist.

Like, wow.
Omniscient, omnipresent, omnipotent, immortal beings whose very ways are mysterious to the minds of men...

wait, wait, don't tell me...

By Sven DiMilo (not verified) on 27 Apr 2010 #permalink

negentropyeater,

How do you know? Past historical evidence doesn't seem to indicate that we have been that interested in preserving other cultures (eg pilgrims vs indians). Maybe we've changed, but I wouldn't bet on it, nor on that of Aliens coming to earth being interested in preserving human cultures.

I am basing that assumption (which is highly speculative of course) on the fact that our current drive to find life in the universe is based on curiosity and science. We have absolutely changed since the times of continental explorations, and that is thanks to the Scientific Revolution and democracy.

By besserwisser (not verified) on 27 Apr 2010 #permalink

You're forgetting Fermi's paradox.

The problem with Fermi's Paradox is that it assumes intelligent life would be interested in us and that they'd let us know.

See also Theodore Sturgeon's semi-classic short story "Occam's Scalpel" short story and Roger Zelazny's unfortunately-not-very-good novel Bridge of Ashes -- both use the idea of aliens terraforming Earth for their own purposes (basically via fossil fuel burning and other pollution).

By Ranting Nerd (not verified) on 27 Apr 2010 #permalink

I don't know why, but I find this the most fascinating way we could potentially end:

http://en.wikipedia.org/wiki/Blame!

It's take on the von Neumann replicators, accept our solar system is replaced by a city sans Ring World instead. Where it's operated by AI factions that don't get along with each other at the detriment of the human race.

Maybe on Earth. Maybe in our Future...

(I also confess...I maybe a wee bit too much of an otaku for this blog. :( )

@ Marshall (#56)
I agree. We don't do a great job making predictions about our own technological advancements 50-100 years into the future. Speculating about civilizations that could be millions of years ahead of us is futile.

@Brownian (#2)
Thanks for the laugh. :D

By Quinn O'Neill (not verified) on 27 Apr 2010 #permalink

The problem with Fermi's Paradox is that it assumes intelligent life would be interested in us and that they'd let us know.

Not necessarily. At least how I think of it is that in all the history of the galaxy, it would only take one civilization that achieved galactic-scale presence to leave evidence all over the place, whether or not they even knew we existed. Star-system-scale engineering, past terraforming efforts, garbage dumps, stray radio, microwave or laser-communication, von Neumann replicators, etc.

I also haven't seen anyone bring up Vonnegut's short story "The Great Space Fuck," in which we send our genetic material out into the galaxy, and to honor the occasion finally formalize the spelling of the last unformalized profanity "jism".

Kids today. They just don't know the classics!

By a_ray_in_dilbe… (not verified) on 27 Apr 2010 #permalink

If the diversity of life on this planet is any indication of life on other worlds then it would be safe to assume that species extinction is a common occurrence in the universe; not just by environmental change, but that brought on self-destruction and cosmic events as well. The question is how common is it for any dominant species anywhere to acquire enough intelligence and knowledge to overcome this evolutionary process enough to bridge the gulf between the stars. The distances are just too mind-boggingly great, the physics of interstellar travel too uncompromising, for me to believe travel to distant stars is anywhere near likely for any species faced with this unrelenting evolutionary process. I think Hawking has a right to be fearful of aliens if they show up at our doorstep. They are either the luckiest bastards in the cosmic game or have evolutionarily grown beyond the threat of their own demise.

what would be the interest in this planet out of all other planets that would be between here where we are and where any aliens with the technology to get here would originate?
What resources would exist here that are not easier to exploit places than our gravity well.
The Asteroid Belt is made of what rocks and dust to very large asteroids and some of them a least judging by what crash to earth made out of Iron. The Oort Cloud contains comets which are water and methane so they would not even need the oceans nor the oil fields all accessible without much of a gravity well to contend with.
I doubt that any advanced civilization with the technology to get here would still be basing its energy needs on the ability to boil water like even our own Nuclear Power plants do.
The only thing that makes this planet unique is _ life and intelligent life may be very rare indeed. Hacking may be right but it might be a that they come and destroy us as the contact causes us to culturally collapse at least that part of the population that are fundamentalist and creationists religious believers which is admittedly large proportion of the population.The result of cultural shock a known phenomena.

By https://me.yah… (not verified) on 27 Apr 2010 #permalink

Hate to rain on everybody’s parade, but interstellar colonization just barely makes more sense than virginal godmothers.

Sending something the size of the Shuttle to the nearest star in about a decade would require about as much energy as the entire species currently consumes in a year — and that’s just to get somewhere that’s a fraction of a percent of the way to the center of the galaxy.

You can either go fast, in which case you need a significant fraction of the energy output of a star; or you can go slow, in which case you need…a significant fraction of the energy output of a star.

Because, at geologic time scales, rubber, plastics, lubricants, and all the rest turn to dust. Even air escapes from steel containers the same way that helium does from a balloon. So, you can’t just “fire and forget” with a “sleeper ship,” you need to actively maintain the habitat…for tens, if not hundreds, of thousands of years. Or more. (And if you can live happily that long away from a star, why would you be interested in traveling to one?)

So, if you can afford to use significant proportions of your star’s energy output to go jetting around the galaxy, you can also afford to create anything you like from whole cloth. The only thing to gain, at that point, from interstellar travel is another star to tap.

And a civilization looking to stick a spigot in Sol isn’t even going to notice that there’s a planet here, unless it’s to use the entire thing as raw material to feed into a matter converter. Any kind of interest they might have in us would be perfectly well served by some form of digitization and virtualization, and would be trivial for them to implement.

The fact that nobody’s ever observed anything that resembles intelligent stellar-scale engineering should let you rest well enough at night, though. If such a thing is even possible, it’s almost certain we’d be among the first to do it.

Cheers,

b&

P.S. Wormholes and hyperspace and the like, even if theoretically possible, though certainly faster, require even more energy than conventional travel. b&

--
EAC Memographer
BAAWA Knight of Blasphemy
``All but God can prove this sentence true.''

By Ben Goren (not verified) on 27 Apr 2010 #permalink

Whenever this subject comes up I am amused by how many people are so adamantly sure that their ideas are correct and or that other people's ideas are ridiculous. Speculation is great, and fun, but how anyone can think that it is reasonable to hold as firmly to their ideas on this subject as they do to their ideas on more local and mundane subjects for which there is a relative glut of data, is beyond me.

Regarding the idea that interstellar travel is too difficult to ever be practical, which could be true, does anyone really think that our knowledge of the universe is complete enough to warrant holding firmly to this position? Because something seems impossible now, and because we have gained so much knowledge compared to the recent past, we can now say with high confidence what will be possible tomorrow? Our (human beings) track record here really sucks so I am not so confident. How about 1000 years from now? 10,000 years?

Regarding the idea that aliens with technology advanced enough to travel to our solar system wouldn't want anything from us, where is the data? I mean, this is a valid speculation, but I have never been convinced by any argument I have seen that this idea is worth anymore than any other idea about the intentions towards us of any visiting aliens. We just do not have any data to constrain our speculations towards reality.

What if the physical principles that enable practical interstellar travel are discovered by the aliens at a point in their history where in other respects their technology and culture is not much more advanced than our own? What if another species gave them the necessary technology?

Even if the aliens are a million years ahead of us there is no reason to assume that their wants and needs will be completely beyond our ken, or that they will be altruistic. Perhaps they value biological diversity. Even if their knowledge of biology is light years ahead of ours, would they be able to predict, and thereby replicate in the lab, all of the amazing compounds, structures, capabilities and beauty that evolution has cooked up in a biosphere that they have never seen before?

Of course, it is also possible that their are no aliens out there at all. But surely it is way to early to stake out a firm position on this as well.

I like the Sagan quote from Contact, "If there really is no one out there it sure is an awful waste of space" (paraphrased). While this quote alludes to the idea that due to the size of the universe, and therefore due to the staggering number of chances that life could have arisen, that it very likely has, I have to admit that in my case it expresses an emotional yearning as well. I have to constantly remind myself not to hold on too firmly to my arguments until there is more data.

By Darrell E (not verified) on 27 Apr 2010 #permalink

re 30:

2)Galactic cosmic radiation would cut our DNA to ribbons in that time, and we cannot reasonably shield against it (14 cm of aluminum would only cut it down by a factor of 2).

so don't depend on aluminum but several meters of water which is actually quite good at shielding cosmic radiation. Also, if you can accelerate to the near the speed of light, you'd probably be able to generate a strong enough magnetic field to deflect high energy ions (and channel them into your fusion engine)

re 38:

So, you're an alien intelligence hungry for resources. For some reason, rather than heading towards the core, you decide to come here. Okay, fair enough, you're already low on gas. And then, having traveled numerous light years to get here, you decide to mine not one of the gas giants, not Venus with its rich atmosphere (although maybe you can be forgiven there), not Mars, not Mercury, not one of the various moons floating about, not the giant fucking fusion furnace in the center, but… Earth.

did you miss where I said "or even stars" i.e. that "giant fucking fusion furnace in the cente"? Also, what makes you think I was saying they would only chew up the Earth? If they are fueling their ships on planets, I think they would probably use them all.

Not necessarily. At least how I think of it is that in all the history of the galaxy, it would only take one civilization that achieved galactic-scale presence to leave evidence all over the place, whether or not they even knew we existed. Star-system-scale engineering, past terraforming efforts, garbage dumps, stray radio, microwave or laser-communication, von Neumann replicators, etc.

Intelligent need not mean "galactic-scale presence". They may just not have gotten here yet. The galaxy's a big place and we're out in the boondocks.

I like the Kilgore Trout novel "Venus on the Halfshell", which culminates in the hero confronting "It", the gigantic cockroach who is the oldest living thing in the universe. The universe, as it turns out, is entirely populated by creatures and races (including the human race) that evolved from huge heaps of cockroach dung left behind by the ancient scientists as they set up research outposts throughout the then-unpopulated universe. If you like Douglas Adams, you'll love this book. It's like Douglas Adams with somewhat more adult themes. Our hero gets more alien tail than J. Tiberius Kirk.

By Mike in Ontario, NY (not verified) on 27 Apr 2010 #permalink

I always thought that the Evil, Alien Esquimaux were already here (see Hayden Howard's novel from the late '60s--- "The Eskimo Invasion"). After all--- if not aliens, then just who did devour the Beothuk tribes.

Since the Vile, Batrachian Manxmen crawled up from their Innsmouthian lairs and the Loathsome, Unhuman Andaman Islanders arrived from the Hell Dimensions--- it's getting to be a bit crowded here...

By DesertHedgehog (not verified) on 27 Apr 2010 #permalink

Darrell: I agree with you. As I said, we are making predictions about technology millions of years ahead of us. The rate of technological improvement works somewhat exponentially (not quite as much as crazy Kurzweill thinks, but there is an element of truth). Someone above posted that it's possible aliens would be "complacent" with their technology and not improve it. Hate to say it--there will always be problems with SOMETHING, and any being will find a way to improve it. But also, remember words like "better" and "problem" might not apply at all to these aliens in the same way they do to us. They might all be a single organism, or anything we can dream up. We are so, so confined by our preconceptions of life due to the specific evolutionary history of our planet that we totally lack imagination for what type of "life" is possible out there. Life doesn't need self-awareness, or even awareness at all.

Along a similar vein, we can't predict the limitations or technology of space travel that far in the future. What makes us think that the aliens need space ships? Maybe they convert themselves to energy and travel as electromagnetic waves until they reach their destination. Maybe they generate a different spacetime through which they briefly travel and emerge in the original? Maybe they simulate reality to near-enough-perfect approximation, and just enter the simulation instead of entering the real reality--if they simulated it perfectly, it's the exact same thing, and the "humans" in the simulation, who are blogging on Pharyngula, would be amazed at the emergence of aliens.

We can't predict at all, and we can't apply our current situation to these aliens. They're too different and too advanced.

re 78:
The Asteroid Belt is made of what rocks and dust to very large asteroids and some of them a least judging by what crash to earth made out of Iron.

IIRC the total mass of all the asteroids in the Asteroid Belt is somewhat less than half that of the Earth. So if they need iron and silicon, Earth and Venus are probably the best bets. And all this talk of the "gravity well", I suspect that if you can travel interstellar and chew up planets, gravity wells aren't much of a problem.

Someone mentioned that there could be a lot of life out there that is successful but not intelligent enough to develop technology. There's also the problem of getting the sequence of the development of life on a planet in the right order.

If humans had somehow evolved very early, before all those ages with dinosaurs and such, there would not be any oil under the surface of the earth to spark the industrial revolution. So there could also be a lot of planets with intelligent life that may never move beyond the equivalent of the stone age.

Intelligent need not mean "galactic-scale presence". They may just not have gotten here yet. The galaxy's a big place and we're out in the boondocks.. - tsg

Von Neumann replicators would take only millions, or at most tens of millions of years to cover the entire galaxy. Either there are no technological civilizations in the galaxy much older than us, or they know about us already.

By Knockgoats (not verified) on 27 Apr 2010 #permalink

Wow, for a moment, I read the title of this article as "Hawking Aliens"! And wondered what new film it was about.

Back to the topic.

PZ, we should add Razib Khan on the list of scientists pondering hypothetical alien encounters. He's reasonably unoptimistic. And wonders why the Von Neumann replicators aren't here already!

By irenedelse (not verified) on 27 Apr 2010 #permalink

maybe Phil Plait is right, and advanced alien civilization will discard biology and advance in machine mode - PZ

With complete certainty, I'd say they will not be unmodified biology. What are the chances of a kludgy process like natural selection coming up with the best way to produce intelligence?

By Knockgoats (not verified) on 27 Apr 2010 #permalink

Intelligent need not mean "galactic-scale presence". They may just not have gotten here yet. The galaxy's a big place and we're out in the boondocks.

I hear you.

There's been So Much Time, though. The "only one" scenario assumes a technological civilization that bootstrapped its way out of planetary-scale resource scarcity and began to expand. Take the von Neumann replicator idea, exponential growth fills the galaxy on a short timeframe compared to the life of the galaxy. Out of however many technological species that have arisen in the last, say, seven or eight billion years, again, only one needs to have gotten to that level and felt the urge to explore or the necessity to expand. That not one apparently has suggests that the constraints are tighter than we imagine, and that prior civilizations have all either failed or just decided to stay home and mind their own business (a possibility, but, yet again, it would only take one expansionist species, in billions of years). I tend to believe that technological civilizations are short-lived creatures.

Von Neumann replicators would take only millions, or at most tens of millions of years to cover the entire galaxy. Either there are no technological civilizations in the galaxy much older than us, or they know about us already.

That's still assuming they'd send them out this far.

re 87:

If humans had somehow evolved very early, before all those ages with dinosaurs and such, there would not be any oil under the surface of the earth to spark the industrial revolution.So there could also be a lot of planets with intelligent life that may never move beyond the equivalent of the stone age.

Seeing what burning all that oil is doing to our climate, maybe that wouldn't have been a bad thing to not have those oil reserves. Does not necessarily mean we would never have advanced beyond the "stone age" (I think we got considerably far from the stone age before discovering oil BTW). But we may have developed more sustainable energy technologies earlier. Or maybe a slower growth rate would have been better. Coal and oil may have been like giving a loaded gun to an infant; too much power too soon. I don't believe that without them we would be "stuck" in a pre-industrial society forever.

And wonders why the Von Neumann replicators aren't here already!

How do we know we aren't them? OR that viruses aren't?

Enough of our ignorant narcissism. Hasn't our own history taught us that homo sapiens is neither the center nor the be-all-end-all of all things terrestrial & celestial?

Then God said, "Let us make man in our image, in our likeness, and let them rule over the fish of the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground." [Genesis 1:26]

NOT!

The earth is the center of the universe.

NOT!

So homo sapiens "sapiens" is the only "highly"-intelligent lifeform in a universe of 1,000,000,000,000,000,000,000,000 stars (give or take a sextillion or three)?

NOT VERY LIKELY!

By The Devil's Chaplain (not verified) on 27 Apr 2010 #permalink

There's been So Much Time, though. The "only one" scenario assumes a technological civilization that bootstrapped its way out of planetary-scale resource scarcity and began to expand. Take the von Neumann replicator idea, exponential growth fills the galaxy on a short timeframe compared to the life of the galaxy.

The biggest problem I have with the von Neumann replicator idea is that it requires a civilization that was technologically advanced enough to produce von Neumann replicators and not consider the danger of machines that reproduce at will without limit. And what would be the purpose of sending them way the hell out here?

Out of however many technological species that have arisen in the last, say, seven or eight billion years, again, only one needs to have gotten to that level and felt the urge to explore or the necessity to expand. That not one apparently has suggests that the constraints are tighter than we imagine, and that prior civilizations have all either failed or just decided to stay home and mind their own business (a possibility, but, yet again, it would only take one expansionist species, in billions of years). I tend to believe that technological civilizations are short-lived creatures.

I don't necessarily disagree with any of this, but it doesn't rule out significantly advanced civilizations that just don't have the technology to get here. Millions of years old? That's probably a stretch. But the sheer size of the galaxy puts quite a lot of stars quite far away.

PZ: Anyway, my bet would be on interplanetary biowarfare, the slow infiltration of engineered organisms to change environments for alien compatibility... I also think the possibility of that happening to us is unlikely.

If it's at all possible (the density of intelligent life is high enough that the nearest civilization has had time and a likelihood to reach us) -- then it already happened.

The scenario you describe is the current state of affairs on earth --- a bunch of stuff running around propagating and "terraforming" the earth. The question, the only question, is whether the "terraforming" is indigenous or foreign. The distinction, as of today, is untestable -- the test is to explore enough of the universe to determine whether there's schmutz related to us in our local neighborhood.

If we've been invaded -- we're the invaders. The rest of the team may have never made it, or they're here and we don't recognize them, or the goal isn't direct transference -- "terraforming" by itself may be the goal.

But Hawkins' invasion makes no damn sense at all -- why would a civilization with the capability to travel across the galaxy "come for our resources"??? That's just stupid -- it happens to the best of us. It's like arguing that we're going to invade pond scum "for their resources".

That's not the proper language at all! At worst, we destroy pond scum completely oblivious to the pond scum, to advance goals and "resources" that the pond scum doesn't understand and is in no way an invasion, and which the pond scum can in no way intentionally avoid.

By frog, Inc. (not verified) on 27 Apr 2010 #permalink

I don't believe that without them [fossil fuels]we would be "stuck" in a pre-industrial society forever.

Hypotheticals like this are hopeless of course, but I disagree. What else is there (on Earth anyway)? How do you build a hydroelectric dam, or a windfarm, or a manufacturing plant for photovoltaic cells, without fossil-fuel powered technology? How do you mine uranium and build reactors? Essentially all of the truly radical alterations to our lifestyle via technology have postdated the massive exploitation of coal and oil.

And "we got considerably far from the stone age" (metallurgy, etc.) largely by cutting down forests. How much longer would that have lasted had we not started mining coal?

We really don't know enough about the distribution of life, intelligence, and technology in the universe. Observations suggest that technology at least is quite rare.

I would predict that life is very common, intelligence very rare, and technology rarer still.

This fits with what we observe on Earth: Life is everywhere, but intelligence is limited to apes and cetaceans, and technology is limited to a subset of humans.

Aliens have no reason to colonize us. If they can get here, they must be more advanced; if they are more advanced, they can surely defeat us in war; but why would you mine Earth and have to bother with its indigenous life when you can get all the same stuff from Mars or Jupiter?

The reason that humans colonized other humans is precisely that they are so similar to each other; when the Conquistadores came to North America they found large supplies of food, materials, and labor.

But alien cephalopoids have no reason to think of Earth land as valuable or humans as useful labor. Maybe they'd want our oceans, but we have plenty to share actually. If they want heavy metals, they'd be much better off mining asteroids. The more different aliens are from us, the less we have to fear from them.

On the other hand, if they are a lot like us, then they might be interested in colonizing our planet---but then, we can also expect them to feel some empathy for us. Advanced technology is not proof of advanced society, but it is evidence of it; if the aliens are composed of battling kin clans fighting over every last scrap, they are unlikely to be able to organize an interstellar space program. Conversely, if they've figured out how to get along with each other, maybe they can figure out how to get along with us too.

I'm more worried that they will arrive, with every intention of engaging in peaceful trade; but then they will commit some cultural snafu, and we will unleash nuclear warheads upon them. This will damage a few of their diplomatic vessels, they will rule us too dangerous, and in a few years military vessels will arrive to scour our planet to cinders.

Actually, this may be what happened to colonized human cultures; the Native Americans and Africans who peacefully traded with European colonists seem to have fared much better than those who tried to fight wars over the land.

It's not that we'll kill them or they'll kill us---it's that we'll kill us through them.

By pnrjulius (not verified) on 27 Apr 2010 #permalink

This is what your mind does when you're not wasting it on sophomoric jabs at religious idiots? Good show!

By strangebeasty (not verified) on 27 Apr 2010 #permalink

@Knockgoats: Von Neumann replicators would take only millions, or at most tens of millions of years to cover the entire galaxy. Either there are no technological civilizations in the galaxy much older than us, or they know about us already.

Von Neumann Replicator: an artificial construct that is theoretically capable of autonomously manufacturing a copy of itself using raw materials taken from its environment. (wikipedia)

That's a good enough definition. What's the distinction between any organism and a VNR? That we haven't built it. If we were to build one, what would be a good model? A microorganism. What would happen to it once it went wild? It would cease being "artificial" since it would autonomously evolve.

So either we are the aliens, or they're much too far away to ever contact. Whether the older ones bothered to track what happened with all the crap they dumped is a separate question.

By frog, Inc. (not verified) on 27 Apr 2010 #permalink

The main problem with this kind of prediction is it presumes we're advanced enough to be able to figure out how the best strategies would go. Given the difficulty humans have in even recognizing when simple co-operation is and is not advantageous, I'm a little skeptical we can even handle the recognition problem efficiently, let alone the search.

That said, although there is prospect of some degree of co-operation, some degree of competition seems exceedingly likely in interspecies/interbiosphere "diplomacy".

The biology in the Chtorr series might be of mild interest to PZ, which may involve similar tactics to his suggestion; however, the politics and Heinlein-esqe MilSF writing might be irritating enough that wading through it would outweigh the interest.

Instead, I'd suggest David Brin's short story "Lungfish" (which influences my view) as a better waste of less time.

It's all incredibly speculative...

But how do we know there isn't a galactic government that punishes starfaring societies for interfering with indigenous cultures? That would explain, in fact, why we haven't heard from anyone---they're not allowed to talk to us, until, say, we invent antimatter propulsion or some such.

Maybe there is in fact a Federation with a Prime Directive after all. When we become warp-capable, we will take our place in galactic society.

Or maybe the universe is as vast a wasteland as it presently appears, devoid not only of technology, but indeed of life except for a few scattered pockets like ourselves.

In between we can imagine benevolent aliens, evil aliens, competing factions of different aliens with different views...

It's all good fodder for science fiction, but it's really not a productive use of time for actual scientists.

By pnrjulius (not verified) on 27 Apr 2010 #permalink

If we were to build one, what would be a good model? A microorganism. What would happen to it once it went wild? It would cease being "artificial" since it would autonomously evolve.

Freely evolving, ever-expanding interstellar population of self-replicating machine "microbes"? What a lovely idea. Why exactly would any civilization want to unleash such a plague of Grey Goo(tm) upon the rest of the galaxy?

Well, I guess some kind of machine-worshipping crazy cult might explain it, but other than that it just seems like peeing in the galactic pool.

By Sclerophanax (not verified) on 27 Apr 2010 #permalink

As Atheists we're forgetting one important reason why aliens would want to visit us. They're spreading the word of GOD (their version of it anyway).

I like Mythbusters like everyone else but it can be a little fluffy at times. Seems like have the episodes end with them blowing up shit for the sake of blowing up shit. IMHO the best use of the show would be to demonstrate why shouldn't things be done and to show why some of our fears are irrational.

There was one good part about that show. Near the beginning Hawking mentions the odds of life existing are remote, but like the lottery someone always seems to be winning every week.

There is a fun quick read SF novel that explores this idea of sending humans to populate a distant planet. "Voyage from Yesteryear is by the author James P. Hogan"
Some interesting themes in the story that would be of interest to this group: 1) The original colony of humans send were educated by robots and developed a whole new society because they had a completely fresh start. 2) their economy was based on recognition and the bartering of ability with no money needed 2) The society was completely atheist and humanist---a second wave of humans that had been brought up on Earth that arrived with their irrational believe in gods were ridiculed. 3) The new society was science/reality based with little or no ideology.

By The Naturalist (not verified) on 27 Apr 2010 #permalink

Seems like have the episodes end with them blowing up shit for the sake of blowing up shit.

Yeah, and?

"Freely evolving, ever-expanding interstellar population of self-replicating machine "microbes"? What a lovely idea. Why exactly would any civilization want to unleash such a plague of Grey Goo(tm) upon the rest of the galaxy?

Well, I guess some kind of machine-worshipping crazy cult might explain it, but other than that it just seems like peeing in the galactic pool."

Don't presume humanity holds the monopoly on stupid ideas... by statistics if there are alien races and such technology is possible at least one of them will have created something that fucked them over and wiped them out.

Don't presume humanity holds the monopoly on stupid ideas... by statistics if there are alien races and such technology is possible at least one of them will have created something that fucked them over and wiped them out.

It seems to me any civilization that would be that short sighted would have wiped themselves out long before that particular technology became available to them.

We have absolutely changed since the times of continental explorations, and that is thanks to the Scientific Revolution and democracy.

The stupid burns bright here.

Never mind that 2,000 square mile oil slick off Louisiana.

By Douglas Watts (not verified) on 27 Apr 2010 #permalink

Sounds like you're talking about Tyranids

Sclero: Freely evolving, ever-expanding interstellar population of self-replicating machine "microbes"? What a lovely idea. Why exactly would any civilization want to unleash such a plague of Grey Goo(tm) upon the rest of the galaxy?

First, it only takes one accident. Second, what else would you do if you lived in a fertile but empty galaxy that you could never colonize, because, well, direct colonization is pointless and uneconomical? It makes perfect sense to me -- the one monument, the one immortality that you could have is to "terraform" the galaxy -- seed it with life.

It's what life does. Since we have no way to test whether life is indigenous to the earth or not -- we have no way, other than circularly, to figure out how long does life take to spontaneously develop and the probability of such spontaneous development, it makes as much sense to claim abiogenesis here as it does to claim abiogeneis elsewhere + migration.

It's not a useful hypothesis in terms of researching abiogenesis because of our limited evidence about the conditions elsewhere in the galaxy -- we might as well assume that the conditions of abiogenesis are exactly like those of the early earth -- but we should do it with at least a self-awareness that it is merely a convenient assumption.

I mean, we already are working on "artificial life" -- we already are on the verge of developing VNR, and we've already designed much of the technology needed to spread them. It shouldn't take very much to design microbes that replicate a solar-sail technology; it's really not much more complicated than many fungi's methods of dispersal.

Who would be surprised if we manage to survive a few centuries that someone wouldn't do something like that? And it only takes one lab!

Folks lack imagination.

By frog, Inc. (not verified) on 27 Apr 2010 #permalink

Interesting idea. I certainly number biological warfare among the more effective means of interplanetary warfare for lots of reasons, but hadn't quite thought of it as evolutionary warfare, which is what you seem to be talking about.

In any event, I think the people who want to wave their arms or invite the aliens are crazy. They're not just a little crazy, either. They really need to get out more.

By https://openid… (not verified) on 27 Apr 2010 #permalink

I think the technology for fixing any environmental problems, lack of resources, food, or space another civilization might have pose far less difficult problems than interstellar travel. So to my mind, expecting aliens to come all the way here to steal our water or eat us or whatever is kind of like imagining the US invaded Iraq because we wanted to raid their fridges.

So what if the aliens happen to be tyrannical, expansionist warlords who want to conquer the universe? I still think you're not fairly stacking up the difficulty of using interstellar travel to satisfy those impulses vs. other technologies. For instance, it would probably be possible to fully simulate or create entire worlds to conquer, in such realistic detail that the distinction between them and reality would become basically meaningless, before it will be possible to travel interstellar distances. Going to another galaxy to "do it for real" would become absurd. Of course this is all total speculation - who knows what technologies another civilization will develop, and in what order - but I think people who worry about a traditional Hollywood alien invasion aren't really thinking big enough.

My favorite "space aliens find Earth" scenario is that they realize that humans are largely harmless and that they can deal with us because we're at least capable of negotiating. But they sterilize the planet anyway because of the ants, fungi, and bacteria - which are too stupid to negotiate with, utterly ruthless, and incredibly hard to eradicate.

Another thought is that some kinds of alien probes (say, a von neumann probe) designed to operate consistently over long periods of time would be designed so that they evolved minimally over that time. Because otherwise they'd become independent and lose their sense of mission. Such a probe would be what passes for horrified by a planet teeming with lifeforms that competitively evolve fairly rapidly. Something that experiences existence on the scale of tens of thousands of years would see bacteria evolving at lightning speed - that'd be some scary shit indeed. Nuke it from orbit; it's the only way to be sure.

By https://www.go… (not verified) on 27 Apr 2010 #permalink

My two cents -

1) Drake's Equation assumes that it doesn't matter where the stars are in a galaxy. I think it really does matter. Most of the stars in a galaxy are near the centre. Not a good place for life. Far too likely to be sterlised and/or destroyed by nearby supernovas etc, disturbed by neighbours, eaten by black holes, etc etc to provide the stable conditions for the billions of years needed for evolution.
The odds are that any intelligent, technologically advanced beings, just like us, would originate in the relatively quiet outer reaches of galaxies, at the ends of spiral arms, or in the spaces between them, or well outside the galactic plane. (Hell, I wouldn't even want to go anywhere near the centre of a galaxy). All this makes the average distance to the next alien even greater.

2) Why does anyone think terraforming Mars is a good idea? You go to all that trouble and then (not being close enough to the Sun, and not having a moon large enough to stabilise the rotation) Mars, as it does irregularily, flips over on its side. Overnight the seasons, and the climate, go haywire. Not good for life beyond the bacterial stage.
The only places worth terraforming are planets such as Earth, with a large, nearby companion, or a large moon (with a fixed rotation axis) of a giant planet. AND they need a magnetic field to retain any atmosphere created.

By Ring Tailed Lemurian (not verified) on 27 Apr 2010 #permalink

How peaceful it looks..

By RijkswaanVijanD (not verified) on 27 Apr 2010 #permalink

The obvious answer to Fermi's paradox is that superluminal travel isn't possible and therefore any sufficiently advanced intelligence capable of interstellar travel is also intelligent enough to realize it's pointless. When you get to the point where you'd need to invest planetary levels of economic output to send a robot to say "hello!" from a civilization that will be dead by the time its recipients get the message - who cares? If you have probes moving at relativistic speeds I suppose they might go "wow! look, intelligent life. too bad it'll be gone by the time I think about slowing down. as if I could. oh, well."

Take Barnard's star, for example. To get a 5,000lb payload there in 5,000 years assuming a perfect matter/antimatter reaction engine, you need an antimatter tank that's something like 1km long by 300 meter diameter (those estimates are cribbed from Alan Cromer) -- and we already know that there's no point in going to Barnard's star. The farther out you get, the more pointless it is.

Super intelligent aliens are sensible enough to realize that interstellar travel is completely pointless. Unless you assume there's "hyperdrive" - but at that point you may as well posit time travel and teleportation and techno-godhood. It's probably safe to say that jesus is vastly more likely to come again, than aliens are to visit.

By https://www.go… (not verified) on 27 Apr 2010 #permalink

re 117:

Drake's Equation assumes that it doesn't matter where the stars are in a galaxy.

Drake's equation makes no such assumption. It is purely a statistical equation. If you think that you need to exclude all the stars in the center of the galaxy, that is fine, just use that ratio (stars in the arms vs total stars in the galaxy) for the appropriate variable in his eqn.

We all seem to be missing the likely scale of any civilization sufficiently advanced to traverse star systems.

When the aliens come, they won't be manning spaceships; they'll be shuffling around Jupiter-sized deathstars.

And they won't be mining our planet; they'll be harvesting our sun on their way home from a field trip to Alpha Centauri.

They may even take a few nanosecs to beam up a few earthly DNA specimens for lab students.

And it won't be war; it'll be magic.

Any sufficiently advanced technology is indistinguishable from magic. ~Arthur C. Clarke

By The Devil's Chaplain (not verified) on 27 Apr 2010 #permalink

It makes perfect sense to me -- the one monument, the one immortality that you could have is to "terraform" the galaxy -- seed it with life.

Are we still talking about the self-replicating Von Neumann probes that can travel from star to star and evolve freely? Because if we are, then what you are proposing is that an intelligent species would want to replace any extant organic life in the galaxy with inorganic synthetic life of their making. There's no telling if the replicating machines would ever even amount to anything more than mindless interstellar nasties, forever spreading from star system to another, gobbling up anything they can to replicate and possibly eventually destroying any chance of organic life ever again evolving into something comparable to the original machine builders.

Then again, it doesn't seem like this is what you are talking about at all, but rather building something spaceworthy that is not a VNP to carry some scratch-built microbes to new worlds. That's a whole different thing and has no bearing on the whole question of why the VNPs aren't here yet.

By Sclerophanax (not verified) on 27 Apr 2010 #permalink

They may even take a few nanosecs to beam up a few earthly DNA specimens for lab students... to see how their 5th-grade seeding experiments turned out.

~IANVS

By The Devil's Chaplain (not verified) on 27 Apr 2010 #permalink

I just had a whole little mental fugue-fantasy about the storm of von neumann probes finally arriving - all offering easy credit terms, enhancement of omnigender sexual apparatus, and "your email address has won one point six two billion freebles; contact bank immediately!" marketing messages, stripping space behind them like locusts, unstoppable, unkillable, self-replicating...

By https://www.go… (not verified) on 27 Apr 2010 #permalink

Super intelligent aliens are sensible enough to realize that interstellar travel is completely pointless.

Assuming, of course, that all super intelligent species will just stop before they figure out how to completely re-engineer/replace their bodies to the point where they aren't even organic anymore and reach practical immortality. If you can just switch off for millenia and then wake up again like no time passed at all, traveling between the stars isn't such a crazy idea.

By Sclerophanax (not verified) on 27 Apr 2010 #permalink

PZ's summary sounds like a Cherryh novel.

By jbirchett (not verified) on 27 Apr 2010 #permalink

Any sufficiently advanced technology is indistinguishable from magic. ~Arthur C. Clarke

I disagree with Clarke on this one. On the contrary, after a certain level of technology there is no more magic. If the aliens appear and they turn out to be riding space brooms and waving wands we'll still assume that they're using technology that is simply so vastly superior to ours that it appears magical...but that it is nonetheless technology.

Fermi paradox? What paradox? Rare Earth.

What if the aliens are just hungry from a long space flight and see terrestrial life as an easy snack?

The probability that they've got the same set of amino acids is laughably small.

David Brin's short story "Lungfish"

Remarkably interesting. (I just read the whole thing.)

Except he seems to mean "mudskipper" by "lungfish". :-(

AND they need a magnetic field to retain any atmosphere created.

That's gravity, not magnetism.

Super intelligent aliens are sensible enough to realize that interstellar travel is completely pointless. Unless you assume there's "hyperdrive" - but at that point you may as well posit time travel and teleportation and techno-godhood. It's probably safe to say that jesus is vastly more likely to come again, than aliens are to visit.

LOL! You could be right :-)

By David Marjanović (not verified) on 27 Apr 2010 #permalink

David M

That's gravity, not magnetism.

I realised after posting that that sentence might be misunderstood. I should have been clearer. You need a magnetic field to prevent the solar wind from stripping away the atmosphere. Mars has gravity (of course) but has lost its early magnetic field, and has thus lost whatever atmosphere it once had.

(Excerpt below from "Mars Global Surveyor for Kids")

As magnetospheres go, though, the Earth is not anything too special. Mercury, Jupiter, Saturn, Uranus, and Neptune all have magnetospheres, and all but Mercury's dwarf ours. Our sister planets, Mars and Venus, are the oddballs: space probes have found no evidence of structured magnetic field lines on either planet, only traces. Since magnets lose their magnetism when heated a lot, it makes sense that Venus, where it is hot enough to melt lead, does not have a magnetosphere. Therefore, it is Mars that is the real mystery: it is pretty cold and is quite like Earth in many ways . . . so why no magnetosphere?
Now, the point of the Mars Global Surveyor's magnetometer comes clear. As you are reading this, MGS is orbiting Mars and mapping out the planet's magnetism (or lack thereof) with its magnetometer. Every once in a while, anomalies are found, where some magnetized substance is buried beneath the surface. These anomalies were thought to have come up from a once-magnetized core and kept their magnetism when the planet lost its overall magnetism.

By Ring Tailed Lemurian (not verified) on 27 Apr 2010 #permalink

Sclero: Are we still talking about the self-replicating Von Neumann probes that can travel from star to star and evolve freely? Because if we are, then what you are proposing is that an intelligent species would want to replace any extant organic life in the galaxy with inorganic synthetic life of their making.

You're assuming your answer. How do we know that there is extant organic life in the galaxy? Maybe an earlier civilization found that the galaxy was fertile, but that abiogenesis was exceedingly rare -- maybe there was only evidence that it had happened once, in their own galaxy.

How would you distinguish between "inorganic synthetic life" and "organic life"? If it's merely a difference of carbon vs. atom X, that's a parochial assumption, a mere chemical technicality. There's no reason to not synthesize organic (in the chemical sense) machines -- and if they go wild, there'd be no way to distinguish them from "non-synthetic organic machines" given enough generations.

A priori, we have no way to calculate the probability of abiogenesis in a suitable environment. We have one case that may or may not be the root abiogenesis event. We may be the gray goo.

In the long-term and large-scale, VNR are indistinguishable from life. We don't know what technologies would be used, what the motivation would be, and what they would look like from our point of view. A bacterium that could survive interstellar travel and expand at target locations, continuing travel is easily imaginable. It's even more easily imaginable that such a "machine" would lose interstellar capability once it began to evolve in a particular niche.

By frog, Inc. (not verified) on 27 Apr 2010 #permalink

If we're going to talk about probabilities of intelligent alien life as being high or low we should be cognizant of what exactly the denominators in our probability assessments actually are.

Sure, on earth out of trillions of species that have existed, only one achieved technological intelligence, but we should positively expect that any habitable planet will produce trillions if not quadrillions of species.

And sure, earth has existed for 4.5 billion years, and human-level intelligence only for about 100 to 200 000 years or so (as far as we know), with civilization only about 10 000 years, but again, we should positively expect that many if not most habitable planets in the universe will also be at least several billion years old.

And sure, intelligence is an adaptation that makes sense only for a small subset of conceivable niches, and on earth only a few lineages have had the opportunity to take advantage of these limited niches to reach a level of pre-sapient intelligence (primates, cetaceans, corvids, cephalopods, elephants, etc), and of these, only one lineage went on to full technological sapience. But we can positively expect that any habitable planet will be home to a vast array of different niches over time.

In short, if you want to argue that since humanity alone on earth evolved technology after so many years out of so many species, it means that likelihood of intelligent life elsewhere in the universe is low, I can just as validly argue that the best available current evidence suggests that the likelihood of intelligent technological life in the universe is 1 species/1 habitable planet = 100%.

If the frequency of technological intelligences in the universe at any given time is around 1 per galaxy, then the universe would be teeming with trillions of intelligent aliens, and we would had almost no chance of ever detecting, let alone contacting, any of them.

Even if there were a type III civilization in say, the Andromeda Galaxy, we would be hard pressed to detect their existence, or distinguish their activities, if any could be detected, from natural phenomena.

Haldane wrote an article on colonizing the other planets back in the 1920s or 1930s. Back then, he assumed that interplanetary communication would be hard, but that ships full of colonists could reach the other planets safely. He proposed modifying the space colonists, and imagined that they would produce further modifications to improve their adaptation to their new worlds. I think he had short, stocky humans on Jupiter. There were risks. As he noted, the later Venus colonists were used for experimental purposes by the earlier, already adapted arrivals.

We know a lot more about the planets these days, which is why you don't hear a lot about colonizing Jupiter, at least not with anything too obviously human. The 1930s through the 1960s were probably the golden age of science fiction where you could land on Ganymede and set up a hydro-electric plant and go hunting for space venison, and you didn't have to worry about relativistic effects and interstellar travel.

Curse you, physicists and planetary explorers. You're no fun! At least the biologists haven't ruined it all for us. At least not yet.

By Kaleberg5 (not verified) on 27 Apr 2010 #permalink

If intelligent aliens came to this solar system, I think we should positively HOPE that they come to earth with either benign OR hostile intent, as either of those scenarios might actually be better for us than the scenario wherein they simply pass through mining resources while ignoring us.

If they are hostile but come to earth, at the very least they are coming within range of our detection systems and weapons. We might get a lucky shot with a nuke, or they might get overconfident and screw up. At the very least we'd have a better chance of identifying in which direction their base of operations is so we can send them our plea for mercy.

But if they're just passing through harvesting resources from the solar system, and they're sufficiently thorough, we're going to be totally screwed, and we won't even know where the threat is coming from.

If they do any comet mining for volatiles say in the Kuiper Belt of Oort Cloud of sufficient thoroughness, it's almost guaranteed that a large number of orbital paths will be disrupted and a shower of large objects is going to fall into the inner solar system. If they do anything large scale in around Jupiter, the same thing could happen, given how Jupiter's gravity controls how readily comets and asteroids plunge into the inner solar system.

And god help us if they decide to tap the sun. Even the smallest disturbance of solar activity is going to render us completely screwed. A 1% fall (or rise) in solar output? A disruption of the sunspot cycle? An increase in flare activity? What if they're really powerful and really thorough and they siphon enough material from the sun to alter its mass and change its gravity? Or maybe they Dyson sphere the sun, but to save material, the make the sphere inside the orbit of Mercury?

We'd better actually hope that life is rare in the universe if this happens. The rarer life is, the more likely we would be considered valuable and worth preserving by other alien species. We take care to preserve the habitats and protect endangered species like Pandas. We don't think twice about ploughing over an anthill.

And, even if the aliens DO take care not to harm us, we're still screwed. Because the resources of the solar system are the resources we're going to need if we ever want to spread beyond earth (and that's not even considering interstellar travel). We do not want any aliens to be getting to them first.

Huh, funny how ideas pop up at the same time...

Regarding the lack of fossil fuels to kickstart a technical civilization, there is at least the possibility that hydrocarbons can be created under the earth's crust without organic material.

From Boing Boing:

Where does oil come from?

amphiox: In short, if you want to argue that since humanity alone on earth evolved technology after so many years out of so many species, it means that likelihood of intelligent life elsewhere in the universe is low, I can just as validly argue that the best available current evidence suggests that the likelihood of intelligent technological life in the universe is 1 species/1 habitable planet = 100%.

Ain't it fun arguing probability while ignoring the basic premises of probability -- that you don't know the result of your sample before you take the sample? Our one case tells us absolutely nothing about the general probability distribution, since we "sampled" a sub-pdf where the probability of selecting an intelligent life bearing is exactly one -- we know a priori that we exist.

Statistics -- it's harder than folks think.

By frog, Inc. (not verified) on 27 Apr 2010 #permalink

re: #136

Agreed. Of course I don't begrudge anyone who wants to play such statistical mental games, so long as they realize that what they are doing is basically fantasy. These are fascinating questions and its fun to think about them.

And when we use the term "best available current evidence", we must never forget that "best" is relative. If ya got nuthin, zero is the "best" you have.

(Consider this: If we actually discover microbial life extant on Mars, what it means is that the likelihood that we are alone in the universe with regards to intelligence has actually DOUBLED. Because the ratio of known inhabited planets producing an intelligent technological species will have gone from 1/1=100% to 1/2=50%. And if we find some fish-like thing swimming in Europa's ocean? It becomes 1/3=33%. And if there's a prokaryote on Enceledas? 1/4=25%. An exotic ethane-based biosphere in Titan? 1/5=20%.

Of course if we find a tool-user on one of those worlds, that changes things....)

If we're imagining the aliens as potentially launching a conventional imperialist war on us then I'll second what others here said. The aliens won't really want anything we have since what we have is so common in the universe they can get it cheaper nearer to home. Fossil fuels? These guys have starships, they've mastered energy sources far more powerful than any puny oxidation reaction. Minerals? Why strip mine the earth for that though when the galaxy has probably trillions of dead worlds with the same minerals we have. Lebensraum? Maybe, but only if the aliens are similar to us in needs for food, temperature, oxygen, etc... And if these guys can build starships why not just terraform a world nearer to home or build one of those giant orbitals Ian M. Banks has in his culture novels.

The only thing that makes sense to me as a credible threat from aliens would be if they were like us in possessing a powerful science and technology that they then went on to use for irrational purposes. Think of a high tech version of the Christian Crusades for instance, where you've got a war fought over mythological nonsense and possession of "holy" sites. Actually Banks has something like this in the form of the Idirians who are a coalition of advanced alien races that also happen to religious fanatics. So I guess you could have some sort of alien Jihaddis who had read in their holy book that life forms with 4 limbs are unclean (6 being the proper Godly number of limbs) and would come here to wipe us out for that reason.

I tend to discount this latter threat too though since any alien race that was as advanced or more so than us and anywhere near as crazy would destroy itself before it ever got out of it's home system. You know, kinda like we're doing now.

amphiox: Consider this: If we actually discover microbial life extant on Mars, what it means is that the likelihood that we are alone in the universe with regards to intelligence has actually DOUBLED. Because the ratio of known inhabited planets producing an intelligent technological species will have gone from 1/1=100% to 1/2=50%. And if we find some fish-like thing swimming in Europa's ocean? It becomes 1/3=33%. And if there's a prokaryote on Enceledas? 1/4=25%. An exotic ethane-based biosphere in Titan? 1/5=20%.

I think if we're being pedantic, it's worse than that. Currently, the likelihood is a complete unknown -- between a limit of zero and one.

But if we find microbes on Mars, the best estimate goes to ZERO -- 0/1 = 0%, since we can't use the a priori sample of ourselves, since that's not a sample at all. Every finding keeps it at 0%, while increasing our confidence in the sampling.

It's a nasty problem with statistics where it goes against every intuition we have, and I've read statisticians grumbling and arguing over it.

By frog, Inc. (not verified) on 27 Apr 2010 #permalink

PZ is channeling Arthur C. Clarke.

The Songs of a Distant Earth

Didn't Sagan mention that the levels of technological advancement included levels of control on the solar energy output? If we ever get to level 3, I don't think we'll need to go out to other stars for an eternity of human existence (billions of years). Maybe by the time our sun is about to crisp the Earth, we'll be ready to move on.

By rickymjam (not verified) on 27 Apr 2010 #permalink

My pet idea is a little different to PZ's: I think we should design a self-replicating molecule, one capable of storing information in the manner of DNA, that will function in the atmosphere of Venus. We should seed Venus with it and wait around for natural selection to do its work. Why go looking for aliens, when we could have 'em on our doorstep in a mere few hundred million years? Maybe less, if we take a hand now and again.

By paulmurray (not verified) on 27 Apr 2010 #permalink

"My pet idea is a little different to PZ's: I think we should design a self-replicating molecule, one capable of storing information in the manner of DNA, that will function in the atmosphere of Venus."
---

The atmospheric temperature of Venus is around 700 F, hot enough to melt lead. No life can live in it, not even extreme thermophilic microbes, which at best can survive temps. around that of boiling water. Your "pet idea" could use a peer review against an 8th grade science curriculum.

By Douglas Watts (not verified) on 27 Apr 2010 #permalink

Douglas Watts, you think the atmospheric temperature of Venus is the same at the surface than at its upper reaches?

Cripes!

By John Morales (not verified) on 27 Apr 2010 #permalink

Why, PZ! You are an eco-imperialist and bio-blitzkrieger! Your plan would make June 6, 1944 look like a garden party (without ants)!

By Doug Meyer (not verified) on 27 Apr 2010 #permalink

The atmospheric temperature of Venus is around 700 F, hot enough to melt lead. No life can live in it, not even extreme thermophilic microbes, which at best can survive temps. around that of boiling water. Your "pet idea" could use a peer review against an 8th grade science curriculum.

700F is at ground level. The upper atmosphere would be much cooler.

Douglas Watts, you think the atmospheric temperature of Venus is the same at the surface than at its upper reaches?
Cripes!
--

No. But the upper atmosphere, where temperatures are lower than the surface, is mostly composed of sulfuric acid. So I guess it is possible that we could try and genetically monkey with an Earth-based archaeobacteria suited to hot smokers and try to get it to live in a sulfuric acid environment in Venus' upper atmosphere but I don't really get what the point would be.

By Douglas Watts (not verified) on 27 Apr 2010 #permalink

PZ: "If I were in charge of humanity's expansion into the universe, and if light-speed is the absolute limit it seems to be, I'd be sending out robot probes all right…all loaded with the biological seeds to impose human-compatible biospheres on any remotely human-compatible geospheres it encountered."
--

I truly hope PZ said this in jest. If not, he is advocating the random spreading of an entire swath of exotic invasive species onto other planetary biomes without regard to the effect. Since, no biologist in their right mind would ever advocate this, I assume this is a joke.

We already have the results of this type of willy nilly invasive species tampering. It's called the Great Lakes. And Lake Victoria.

By Douglas Watts (not verified) on 27 Apr 2010 #permalink

Douglas @146,

No. But the upper atmosphere, where temperatures are lower than the surface, is mostly composed of sulfuric acid.

Ah, so it's not the temperature (as you first claimed) that's problematic, but the chemical composition?

Hm. According to Wikipedia, Above the dense CO2 layer are thick clouds consisting mainly of sulfur dioxide and sulfuric acid droplets.

I wonder if there are any organisms on earth that metabolise sulfur dioxide, and already tolerate a sulfuric acid environment? ;)

By John Morales (not verified) on 27 Apr 2010 #permalink

Douglas,

I truly hope PZ said this in jest. If not, he is advocating the random spreading of an entire swath of exotic invasive species onto other planetary biomes without regard to the effect.

Since PZ prefaced his comment with "If I were in charge of humanity's expansion into the universe", it's pretty clear that's the intended effect.

Reading for comprehension, you're doing it wrong. :)

By John Morales (not verified) on 27 Apr 2010 #permalink

Thanks, John.

The question I am raising is how a sulfuric acid metabolizing microbe could exist in the upper part of the Venusian atmosphere, esp. given that, unlike Earth, Venus has no appreciable magnetic field to block out harmful radiation. Unlike the proposed Venusian upper atmospheric biome, Earth microbes are either under the full blanket of its atmosphere, or deep under sea, and all are protected from exposure to hard UV and radiation due to the Van Allen belts and the general thickness of the atmosphere. As far as I can discern, an upper atmosphere microbial biome on Venus would not have any of these multiple layers of protection.

By Douglas Watts (not verified) on 27 Apr 2010 #permalink

Douglas, you've reached the limits of my 8th grade science, and I can no longer dispute you. :|

I'll defer to biologists (xeno-biologists?) regarding the survivability of cellular DNA organisms in the conditions applicable to the upper reaches of the Venusian atmosphere; that said, your shift from temperature to chemistry to radiation regime as a basis for your objections is suggestive.

By John Morales (not verified) on 27 Apr 2010 #permalink

@#102:
Yeah, Chtorr! That was the first thing I thought of. PZ's worry – a very plausible one, if we're going to worry about alien attack at all – is that aliens might invade via their ecology, not with guns. The War Against the Chtorr is a great series built on that premise. (If anyone's interested, I was just inspired to toss up a blog post w/ a little more detail on the Chtorr.)

Thanks for the link to the David Brin story; it's new to me. Will enjoy a read now -

By Defaithed (not verified) on 27 Apr 2010 #permalink

If any one was to actually make a
replicant" a Von Neumann machine and they notice some time afterward that they were tending to "take over" and be a problem pushing out everything else, wouldn't it be likely that someone else might build another similar machine with the ability to attack the first one to make copies of itself?
If included in the programing of each was some variability in the copying process enabling them to adapt to the changing requirements. wouldn't that be truly machine evolution?

uncle frogy

By https://me.yah… (not verified) on 27 Apr 2010 #permalink

uncle frogy, you neglect to take into account the Berserker scenario. :)

By John Morales (not verified) on 27 Apr 2010 #permalink

A priori, we have no way to calculate the probability of abiogenesis in a suitable environment. We have one case that may or may not be the root abiogenesis event. We may be the gray goo.

Well, now I know we aren't talking about the same thing. I was still talking about Von Neumann probes sent to travel between the stars and replicate, slowly exploring the whole galaxy. That puts some very strict limits to what they can and can't be. We know for a fact that the harsh, radiation-filled vacuum of space is not a hospitable environment for the kind of replicators we evolved from. Not in the least. If another species engineered our nucleic acid based life to make probes for exploring space, they were both incompetent and stupid. That's like making a volcano-exploring robot out of water ice and butter.

As for your idea, there's nothing fundamentally wrong with it. That is, assuming that any species would want to make carbon and water based VNR:s, despite the fact that they can only function in very limited environments which are bound to be scarce in the galaxy. If, however, they were to build a space-worthy VNP capable of custom-making new replicators to seed any seemingly suitable worlds, they could theoretically use them to seed an entire galaxy with all kinds of life. That is, assuming that the probes themselves didn't start to evolve in a direction where they gave up their mission and just concentrated on their own reproduction Then we'd be back where we started, in a galaxy infected with interstellar space-germs.

By Sclerophanax (not verified) on 28 Apr 2010 #permalink

Let's face it, this isn't worth worrying about. The aliens, if they ever show, will be so different from us that we may not even recognize them as intelligent life despite their showing up in an object able to traverse vast distances in a vacuum.

I'm not worried about alien viruses either. Seriously, what are the chances that alien viruses will even be close enough to DNA or RNA to infect terrestrial life? I'd start to rethink ID if that were true. (And be concerned about the lack of creativity of the designer, but that's another issue.)

Whatever our first encounter with alien intelligence-if it ever happens-will be, it will be nothing like we anticipate. Stop worrying and get on with your life. Speculation is fun, but when it goes over into worrying about infection, time to forget it.

Take Barnard's star, for example. To get a 5,000lb payload there in 5,000 years assuming a perfect matter/antimatter reaction engine, you need an antimatter tank that's something like 1km long by 300 meter diameter (those estimates are cribbed from Alan Cromer) - google@119

Why do you assume you need a payload that size? The smallest natural self-replicators are many orders of magnitude smaller. The first interstellar probes will probably weigh grams not kilograms, and be laser-accelerated, cutting fuel requirements considerably. I would be surprised but not astonished if the first wave were to be launched in my lifetime (I'm 55).

Also, why are you in such a rush? What's 5,000 or even 50,000 years if you do not age and your civilisation is already millions of years old?

I'm always amazed when this discussion comes up, by the quasi-religious obduracy of those who won't accept the Fermi paradox: I suspect it stems from a strong desire for there to be lots of technologically advanced aliens, so the complete absence of the evidence we would expect to see if there were is simply discounted, and claims that interstellar travel is impossible are routinely trotted out, without any attempt to actually find out whether this holds up to examination.

Of course it's possible that Earth is a kind of reservation, but that's about the only plausible alternative to there not being any old civilisations in this galaxy. Hawking is talking nonsense: if they are out there, and are more than a few million years in advance of us, they know about us.

By Knockgoats (not verified) on 28 Apr 2010 #permalink

Dianne,

The aliens, if they ever show, will be so different from us that we may not even recognize them as intelligent life despite their showing up in an object able to traverse vast distances in a vacuum.

??? If Aliens show up in an object able to traverse vast distances, we should be able to conclude that they are intelligent however different from us...

Seriously, what are the chances that alien viruses will even be close enough to DNA or RNA to infect terrestrial life? I'd start to rethink ID if that were true. (And be concerned about the lack of creativity of the designer, but that's another issue.)

??? what does finding alien life with a similar DNA or RNA structure have to do with validating ID? Are you certain there are no other planets in the universe with a similar environement to ours?

Whatever our first encounter with alien intelligence-if it ever happens-will be, it will be nothing like we anticipate. Stop worrying and get on with your life.

The fact that it might be different from what we anticipate (I don't even know what "we" anticipate?) has nothing to do with it being a potential threat or not.

That we shouldn't worry about it too much has more to do with the very small probability of encountering Alien intelligence within the next century or even millenium than whatever speculation about what Alien intelligence might look like.

By negentropyeater (not verified) on 28 Apr 2010 #permalink

"Lungfish" has been added to my reading list.

While we're on the subject, let's not forget James Blish's "Surface Tension".

Sclero: We know for a fact that the harsh, radiation-filled vacuum of space is not a hospitable environment for the kind of replicators we evolved from.

Not true. Currently, most earth organism are incapable of living in hard vacuum -- but we know fairly little about the early replicators, and what capabilities they lost in their evolution.

We do have bacteria & archaea who do survive those conditions -- and they're particularly interesting, because they must have evolved since space exploration started. NASA has a hell of a time sending out sterile probes, because a variety of organisms have adapted to their sterilization protocols which mimic deep space (radiation, hard vacuum, etc).

We have on earth D. radiodurans who are fine with very high levels of radiation, using a multiple copy genome with heavy proofreading -- and that's a "naturally" occurring organism.

We know shit so far. We'll know much more after significant exploration. If we find nothing in the solar system related to us, this idea is bust.

For FSM's sake, we have an entire biome deep underground consisting of microorganisms with 1k generation cycles living off of rock! The flexibility of our relatives is extraordinary. We know shit.

By frog, Inc. (not verified) on 28 Apr 2010 #permalink

I'm surprised at myself for waiting so long to drop into this thread, despite my intense interest in this subject. Ebb and flow of life, I suppose....

Dianne (@127):

Re Clarke's Third Law, I agree. I've mentioned it here, but some years ago I read a criticism of the Harry Potter books that was couched as an inversion of Clarke: Any sufficiently well described magic is indistinguishable from technology.

In this case, I think maybe we've extended the set (dare we call it Clarke's Fourth Law?): Any sufficiently advanced technological society will interpret all apparent magic as advanced technology.

Aside to neg @158: If I'm reading Dianne right, she wasn't doubting that a clearly artificial interstellar object would be evidence of intelligence; she was suggesting that the intelligent life (if any) aboard the craft might be so bizarrely different from life-as-we-know-it that it would be difficult, if not impossible, to recognize it as such. This is especially true if the "life" we're talking about is a machine-based intelligence. Imagine, for instance, a car with a computer housing a true artificial intelligence. Now imagine transporting that machine to, say, Iron Age Britain. The people who encountered it would recognize it as a machine, and as vastly advanced compared to their own technology... but would they perceive it as <>life? And on the off chance that they made that intuitive leap, would they know what part of it was the "life" and what part merely they transportation?

As fascinating as all this speculation is, I suspect it's essentially masturbatory (which metaphor I don't apply trivially: I mean to say it's fun and intrinsically valuable, but ultimately not generative ;^} ). Unless there are fundamental universal constraints that limit evolved biologies to a (relatively, on a universal scale) narrow band of possible forms and morphologies (which I don't consider likely, but about which I'd love to hear the opinions of the biologists here), then life elsewhere is likely to be, as Dianne hints, unrecognizably bizarre. That is, either we live in a Star Trek universe, where the differences between intelligent species are pretty much limited to skin color and ear shape, or extraterrestrial (should I say extrasolar?) life is "not only queerer than we imagine, but queerer than we can imagine."

If there's any life out there at all, of course... but speculations about that (e.g., the Drake Equation and the Fermi Paradox) also strike me as the wildest of guesses: There are fundamental things we still don't know, starting with the mechanism(s) of abiogenesis, that potentially undermine all our assumptions. Suppose, for instance, that we happen to be the oldest technological civilization in the galaxy (or even in the universe), either by chance or because of some unguessed cosmological constraint on how early life could have arisen in the evolving universe? All assumptions about whether, how, and how quickly life might spread through the universe are moot, from our POV, if we're the first. And, of course, it's really impossible to escape anthropocentric projection in making these estimates: We expect intelligent life to fill the galaxy with VNRs because we imagine that's what we would do, if we could... but do we really know that this would be the universal tendency of any intelligent species? Can we even ask that question without contaminating it with anthropocentric bias?

All our speculations are based on assumptions about what intelligence does — what its motivations are, what technologies it uses, what its arc of change might be — that may be not only unfounded but off by many, many orders of magnitude (if we could even imagine how to measure this sort of "offness"). It's hard enough to wrap our heads around how much our own intellectual relationship to the universe, and to other life. As recently as the last couple centuries, "naturalists" routinely killed animals more or less indiscriminately for the purposes of collecting specimens, sometimes wiping out the very creatures they were ostensibly studying; I doubt any scientist would behave that way now. So how do we know whether, by the time we've attained the technological capability to fill the galaxy with VNRs, we'll still want to? And how do we even begin to guess what an unknowably alien intelligence would do with that capability?

It seems to me that the only thing the fact that we haven't met any extraterrestrial life yet really tells us is that we haven't met any extraterrestrial life yet.

But it is fun to go on about it, isn't it?

By Bill Dauphin, OM (not verified) on 28 Apr 2010 #permalink

Knockgoats writes:
Why do you assume you need a payload that size? The smallest natural self-replicators are many orders of magnitude smaller.

Of course. It's just an arbitrary value used to come up with a ballpark figure to illustrate the kind of fuel/weight/time problems involved with even "nearby" interstellar travel. You can just as easily assume that aliens will use massless magical carpets of infinite carrying capacity, if you want to - or self-replicating robots (like a sperm and an egg?) that are very tiny. A lot of the folks who are trying to fantasize that interstellar travel is practical and interesting perform amazing backflips of justification and you're welcome to, as well. But any interstellar travel scenario is going to have to take into account mass of the thing being sent, the energy sent to get it there and decelerate it, and maybe something about the difficulty of building things that work for long periods of time.

The first interstellar probes will probably weigh grams not kilograms, and be laser-accelerated, cutting fuel requirements considerably.

Sure they will. And with laser acceleration they might eventually make it to a nearby star well after the civilization that sent them is dead or has grown into something completely different.

One-way probes are one thing, one-way colonization is another, and there-and-back visits are a third. Can we agree that those are on a scale of decreasing likelihood? Then let's think about their relative value: we've already launched an interstellar probe and, so what? Mankind might still be around if it's found but it'd be some pretty crazy aliens indeed if they embarked on a massively expensive attempt to return a visit within a practical time-frame. As I mentioned in my earlier comment, you can also assume slow-accelerating probes that eventually work up to relativistic speeds - sounds pretty cool until you realize that the probe would have trouble slowing down in useful time; a civilization might rise and fall before the probe could decelerate enough to visit. Interstellar interspecies visits might result in drive-by probe-swaps that amount to rolling down the car window and yelling "have a nice day" - but, so what?

I would be surprised but not astonished if the first wave were to be launched in my lifetime (I'm 55).

Yeah, sure.

Also, why are you in such a rush? What's 5,000 or even 50,000 years if you do not age and your civilisation is already millions of years old?

I'm not in a rush at all because I think it's pointless. But if you're going to fantasize about dialog and/or exchange of knowledge with aliens, then 50,000 year-long email flamewars aren't going to convey much of use.
Us: "hey, do you guys have a technology for fixing global warming?"
Aliens: "sure! here it is! (attachment: freebzarb.pdf)"
Us: ....
Aliens: "hello? h saps? helllooooooo?"
Us: ....
Aliens: "fuck."
Cockroaches: "hello? hello? We are here."
Aliens: "here we go again."

There are 2 issues about time - one is the question of whether you can build a robotic probe that is reliable enough (and the turn-around time between test versions) to work long enough and the other is whether a "conversation" remains useful once the dialog time gets long enough. It might be interesting but at a certain point if all you can say is "evolve into anything cool lately??" then so what? Why bother.

Civilizations millions of years old is a cool idea but a rather whoppingly large assumption. We ought to have a technological civilization of our own that lasts a few tens of thousands of years before we can even fantasize about civilizations lasting millions.

I'm always amazed when this discussion comes up, by the quasi-religious obduracy of those who won't accept the Fermi paradox: I suspect it stems from a strong desire for there to be lots of technologically advanced aliens

I'm always amazed by the way that many people comfortably jump to the hard-to-justify assumption that we'll experience an infinite technological ramp-up that will eventually result in technology that is indistinguishable from magic. Why do we assume that? And why don't we ever take a sober look at the energy usage ramp-up that goes with magic technology? So far, the curves don't look good, and there don't appear to be magic cracks in reality that are going to make us able to casually brush aside space time, system reliability, and so on. We're so wired to want to explore that it seems to me we can't seem to ask whether the whole Star Trek scenario makes any sense at all. That's what I meant about intelligent aliens maybe being smart enough to realize there's no point in trying - send probes? Why bother? Let's just watch them using Hubble Mk XIX and maybe it'll be entertaining but there's no point trying to visit because they'll be dead and gone by the time we get there.

We are programmed to hope and explore. We are evolved to wonder whether there's better living on the other side of a mountain; but we aren't evolved to think realistically about the size of interstellar space. So we have entertainment like Star Trek that caters to our inability to think realistically about this stuff, but it's just entertainment. We can't seem to soberly consider that there might not be infinite technology ramps any more than that there might not be an eventual path to god-hood if we're only clever enough.

If you want to base your assumptions on probes talking between civilizations lasting millions of years you may as well assume that we'll figure out how to twitch our noses and teleport, or that we will just figure everything out so that we are gods and can move backward and forward in time freely at no energy cost. Go ahead. Assume whatever you like. Assume jesus is going to come again, too. It's all going to happen. Sure. Remember the cargo cultists? Why is it that whenever a bunch of humans start talking about interstellar travel and colonization, it always sounds to me like cargo cultists? Sure, the aliens are going to come and teach us how to undo the global ecological collapse and give us free power generators and infinite technology. It'll all be like Star Trek. Uh huh.

By https://www.go… (not verified) on 28 Apr 2010 #permalink

If you want to base your assumptions on probes talking between civilizations lasting millions of years googleperson@162

You are evidently unable to read for comprehension. My whole point is that if technological civilisations last millions of years (the condition for there being lots of aliens around), then interstellar travel is quite possible. The fact that there is no evidence interstellar probes have ever reached our solar system is, therefore, evidence that there are very few if any such civilisations, whether because they only develop under very unusual conditions, or because they don't last long, w

None of your piddling objections have any particular sense to them. Why do you need 5,000 kg payload and a short travel time? You have simply ignored these questions.

By Knockgoats (not verified) on 28 Apr 2010 #permalink

I wonder if there are any organisms on earth that metabolise sulfur dioxide, and already tolerate a sulfuric acid environment? ;)

Does the "wink" mean you already know the answer? Then I will play the fool anyway and point out that there are bacteria living in sulfurous hot springs in Yellowstone in pH around 1 and temperatures near 100C.

Sorry, googleperson, last was accidentally posted prematurely. You have not completely ignored the questions I raised, it's just that your responses make no sense.

It's just an arbitrary value used to come up with a ballpark figure to illustrate the kind of fuel/weight/time problems involved with even "nearby" interstellar travel.

If you assume 5,000 Kg, and what is needed is 5g, that's not a "ballpark figure", is it? It's out by 6 orders of magnitude.

As for travel time, you are simply assuming that civilisations can never last long. Why?

And drop all the stupid blether about Star Trek, etc. It does nothing for your arguments.

You can just as easily assume that aliens will use massless magical carpets of infinite carrying capacity

Crap. These are impossible according to everything we think we know about physics. Interstellar robot probes are not.

Why is it that whenever a bunch of humans start talking about interstellar travel and colonization, it always sounds to me like cargo cultists?

Because you're an idiot.

By Knockgoats (not verified) on 28 Apr 2010 #permalink

googlehash (@162):

IMHO, your it's-way-too-hard-and-you-guys-are-idiots-for-not-knowing-that cynicism is a failure imagination on the same order of magnitude as that of those who imagine an easy Star Trek future is just around the corner.

Of course the challenges are immense, but if we leave out SF stuff like FTL and time travel, all the hurdles we've been discussing — energy conversion, propulsion, radiation shielding, long-term mechanical and biological sustainability, etc., etc., etc. — are matters of technology development and engineering (including, probably, biotechnology and bioengineering), and history shows that it's usually reckless to make pessimistic predictions about technology growth. Yeah, we don't have any fucking flying cars or jetpacks (actually we do have both, kinda'-sorta', but not in that Jetsons way we hoped for), but those things pale in comparison to the simple iPod touch I'm using at this moment to listen to Jethro Tull. The iTouch would've seemed as impossible to people of Darwin's time as starships do to you and me (well, just you, actually)... and in the century before Darwin, building an accurate portable timepiece was considered "the greatest scientific problem of [the] time."

I'm not naively suggesting that the curve or our technology growth will be an effortless asymptotic climb to virtual magic... but I am suggesting it's a mug's game to bet against future technology.

Plus which, your curmudgeonly rant sucks all the fun out of the speculation. Just sayin'....

By Bill Dauphin, OM (not verified) on 28 Apr 2010 #permalink

If Aliens show up in an object able to traverse vast distances, we should be able to conclude that they are intelligent however different from us...

Not necessarily...We might not recognize them as "life" at all and conclude that what we saw was an unoccupied von Neumann machine. Or an abandoned craft. Or we might mistake the crew for decoration or lifestock. We have a hard time recognizing intelligence even when it is in front of us and quite similar (see chimpanzees, dolphins, and elephants as examples of terrestrial intelligence of sufficient level to induce a self-symbol and allow use of tools). We might completely bungle recognizing intelligence that is really different.

what does finding alien life with a similar DNA or RNA structure have to do with validating ID? Are you certain there are no other planets in the universe with a similar environement to ours?

Why should a similar environment necessarily produce an ecosystem in which the same base pairs carry information in exactly the same way as on Earth? Even on earth, a few species of bacteria (IIRC) have slightly different genetic codes (i.e. use other bases besides GCAT, have different translations to protein, etc). In short, I see no reason to think of DNA and RNA as invariant requirements for life anywhere.

On the contrary, if the genetic information of the aliens is coded in exactly the same way as humans' is that suggests a common origin. And since DNA and RNA are not remarkably radiation resistant (on the contrary, as already pointed out), that suggests that they were intentionally implanted on more than one world. There may be something magic (that is, absolutely necessary for earth-like life) about carbon, hydrogen, and oxygen, but I'd be shocked if there is anything magic about DNA or RNA. Other coding systems will do.

And if the aliens have different genetics then their viruses will be completely harmless to us: they simply won't be able to take over our cells to reproduce. (Ok, maybe not completely harmless: we may have allergic reactions against them since any moderate sized molecule can cause an allergic response.) I may be reading people wrong, but I thought I detected a hint of people actually worrying about the effects of alien viruses. Speculating is great. Worrying, not so much.

KG: My whole point is that if technological civilisations last millions of years (the condition for there being lots of aliens around), then interstellar travel is quite possible.

You don't go far enough -- not only must "civilization" last a few million years, but it must be mind-numbingly boring to be stable enough to even communicate with itself.

If we're limited by light communication, you have a huge delay between even close-by, related civilizations. No trade of course is economical for anything but information, and that itself requires that the traders survive in recognizable form over the periods of trade.

We know how much human beings have changed over the last million years -- and that's mostly brute biological evolution, without any "self-evolution" and with negligible contextual change from technological evolution.

Any advanced "civilization" which lasts millions of years is likely to splinter and transform unrecognizably in much shorter time frames. Sure -- you might have descendants of an original civilization, but there's just no way you could have a stable singular civilization that could possible trade and organize itself as a singular entity.

So, I guess we can imagine an interstellar civilization of entities who play shuffle-board endlessly over the millenia, never reproducing or learning anything new. I'm not sure I want to communicate with the galactic retirees.

By frog, Inc. (not verified) on 28 Apr 2010 #permalink

You don't go far enough -- not only must "civilization" last a few million years, but it must be mind-numbingly boring to be stable enough to even communicate with itself.

Nah...they're changing and evolving. But they're using Windows based software for communication: every new update is compatible with every older version. So you can still read messages sent 1/2 a million years ago but it takes another 1/2 million years to load.

Dianne (@167):

Ah, good to see I correctly interpreted (@161) what you meant earlier (@127).

(@168):

In short, I see no reason to think of DNA and RNA as invariant requirements for life anywhere.

Unless, of course, they are "invariant requirements for life anywhere." ;^)

I actually share your skepticism on this point (and, BTW, pretty much everything I've learned about biology since taking HS Bio 1 in 1974-75 has come from reading Pharyngula, so what the &%#$&* do I know?)... but just to play devil's advocate, what if there are as-yet unknown universal constraints that limit the possible mechanisms for abiogenesis and early development of life to just one, or to a small handful? In that case, it might be inevitable that all, or at least a statistically large percentage, of life in the universe would be based on DNA and RNA. That is, the Star Trek universe, in which (with the exception of the odd Horta) intelligent life is very similar wherever it appears.

But I don't really consider that likely; I really was just playing DA. You note that...

...if the genetic information of the aliens is coded in exactly the same way as humans' is that suggests a common origin.

...but I'm not sure common origin necessarily implies design, nor...

And since DNA and RNA are not remarkably radiation resistant (on the contrary, as already pointed out), that suggests that they were intentionally implanted on more than one world. [emphasis added]

...does it necessarily imply intentionality. And neither design nor intentionality necessarily implies gods (i.e., what ususally is implied by ID, which you referenced originally). I guess most folks consider interstellar panspermia unlikely, and directed panspermia even moreso... but my guess is that most of the regulars here consider a supernatural designer vastly more unlikely than either.

Speculating is great. Worrying, not so much.

QFT!

By Bill Dauphin, OM (not verified) on 28 Apr 2010 #permalink

It's really an open question, whether DNA is an arbitrary set of bases or whether it's somehow optimal.

Leaving that aside, considering Dianne's idea that another intelligent species is just as likely to be so utterly strange as to be unrecognizable as somehow "like us", I don't think so. Granted, the long evolutionary process necessary to produce advanced sapience and technology use is going to be massively contingent and there's nothing especially magical about the basic tetrapod form or bipedalism specifically. But evolution, wherever it occurs, is going to find the "good tricks" over and over again, and be constrained by some forced moves. And sapience is not likely to arise without some similar developmental pathways based on environmental constraints as were followed by the primate lineage on Earth.

Ability to locomote seems like a given, so no plant-analogue sapience. Local conditions would have a lot to do with absolute size of the organism, obviously, but the basic constraints of neuro-processing would argue against anything too small to have a CNS of some description, so we're probably talking about something within an order of magnitude of a primate in size (pace Blish, "Surface Tension"). Selection pressure for articulated digits of some sort leading to increased need for serial processing to control said articulation (hands=tools). Pressure for greater attention-control and processing of sensory data on an information-rich channel (sight). Those factors alone would argue against amoeboid forms evolved in dark benthic seas evolving to sapience, for instance, or any really radical deviations from the basic "limbed animal-analogue with something for eyes" body plan.

So I think another intelligent species would be recognizably "animal," and likely will share with us tool use via fine motor control of gross technology-optimized appendages not also employed for ordinary locomotion and visible or near-visible EMR as the primary sensory modality. Within those and maybe a few more constraints, obviously, things could get pretty weird. And even with all the commonalities, it might well be that for humans to lay eyes on such a thing would ineluctably induce Lovecraftian dread (mutual, perhaps), so that the basic, hindbrain evolutionary imperative will scream "kill it! abomination!" no matter how benevolent were the intentions of either party.

And then it would start unspooling the stored genetic information of millions of humans into infants that would be raised onboard, educated by machines, and eventually transported onto the now hospitable planet surface to build a new technological civilization.

Any robot that could successfully raise a human infant to a functional adulthood, would have to be considered a person itself. If you have AIs that are that human, why would you need them to raise meat-babies?

By Mike Crichton (not verified) on 28 Apr 2010 #permalink

And neither design nor intentionality necessarily implies gods (i.e., what ususally is implied by ID, which you referenced originally). I guess most folks consider interstellar panspermia unlikely, and directed panspermia even moreso

I like the "cosmic picnic" theory myself: family of intelligent beings, who happen to belong to the only species in the universe currently capable of space flight, goes on picnic on life free world, leave trash behind. Trash contains DNA and the whole mess starts again...

I'll agree that a common origin does not prove intentional spread, but then you have to explain how something as big and bulky as DNA spread accidentally throughout the universe. If DNA is the common molecule of life throughout the universe. Which would surprise me greatly.

The term ID was used for pure sensationalism.

Diane @ 174 "I like the "cosmic picnic" theory myself: family of intelligent beings, who happen to belong to the only species in the universe currently capable of space flight, goes on picnic on life free world, leave trash behind. Trash contains DNA and the whole mess starts again..."

The idea was first used by Stanislaw Lem in an early short story included in his "Star Diaries" about the bumbling astronaut Ijon Tichy.

In a more serious context, it was used in Strugatsky's "Wayside Picnic" (Piknik na Obotjina) which in turn inspired Tarkovsky's film "Stalker"

The "failure to communicate" was BTW a recurring theme in Lem's writing, "His Master's Voice" is about SETI failing to unscramble the alien signals, and "Solaris" is about the unintentional damage caused by an alien intelligence trying to communicate (the english translation of this book is sub-standard, but the ideas are solid).
-Anyway, aliens are ALIEN, and even more so after going through millennia of synthetic evolution (and possibly re-making themselves as AIs) the speculation about their nature, and motives is likely to end up as projections of our own expectations and fears.

By Birger Johansson (not verified) on 28 Apr 2010 #permalink

Dianne: Nah...they're changing and evolving. But they're using Windows based software for communication: every new update is compatible with every older version. So you can still read messages sent 1/2 a million years ago but it takes another 1/2 million years to load.

Have you ever read the arguments that get involved in "interpreting" the Torah? Or read Gilgamesh? Or the stories from small-scale societies that haven't been heavily "translated"? Or the same for the Iliad?

The only reason they seem understandable is that the "translator" modernizes them to a given interpretation -- but just grab some of the possible "alternates" for the Iliad and see!

That's just for stories that are a couple of millennia out of date. Imagine trying to understand stories told by Neanderthals!

No -- the format can stay the same. But the context changes so much that it's meaningless. Information isn't an object, but a relationship between the messenger and the receiver. You can see that in good encryption -- the difference between a random message and an encrypted message is the relationship between the encrypter and the decoder.

Information is a difference that makes a difference -- that demands that you have proper expectations. There's no way any kind of even mildly sophisticated message can be transmitted over millions of years between evolving entities without some sort of closure -- some way to message the originator back and question them.

By frog, Inc. (not verified) on 28 Apr 2010 #permalink

Damn -- the best example is the use of "Logos" in Christian writing.

No one knows what it means, even though it is the most essential term in Christian theology. Back in the pre-Socratic days, it appears to have been similar to "Tao" -- the nonverbal, non-rationalized public aspect of life. At some point in Helleno-Jewish evolution, it became the breath of God -- not his speech per se, but the vitality that precedes speech. Then at some point the Christians began to interpret it as the voice of God, Jesus and the connection between the highest god and the sublunar world.

The arguments over what John meant are endless. No way to know. And that's in the most public message of Western Civ, only 2kya!

By frog, Inc. (not verified) on 28 Apr 2010 #permalink

@Birger: The Golem stories are Lem's best for this issue. It's right at the edge of communication with the possibility of feedback, yet it's still essentially impossible to really understand what's going on.

By frog, Inc. (not verified) on 28 Apr 2010 #permalink

Given our own record of intra- and inter-species violence (think of all the extinctions we've caused), our creation and use of weapons of mass destruction, and the fouled condition of our nest... exactly why would any sensible alien civilization want to have anything to do with us, anyway?

These "Alien-Monsters-Are-Going-To-Kill-Us!" scare-stories remind me of the "Iraqi-WMDs-Are-Going-To-Kill-Us!" scare-stories that were manufactured to excuse a war of aggression.

Haven't you ever heard a schoolyard bully say, "I had to hit him [the innocent victim] to defend myself [from a nonexistent attack]!"?

Violent people project their violent tendencies and intentions on others — even, as in this case, on others they've never met, who've never come near them, and who may not even exist.

First of all I don`t think we should be going into space like were looking down the sight of a double barrel shot gun. If the aliens were going to sap our solar energy they would have done it allready.You know we think our technology is so advanced and from where we all came from it is.But to people who have done light travel for thousands of years it aint squat. So next time you see sompthing in the sky that you may be privilaged to talk to.They already know where your commin from and where your goin.If they want to do sompthing like steve says theres nothing we can do to stop them.Hell out government wont even deal with the fact there there. You know its time to GROW UP except the fact there here theyve been here for a long time and they`ll be here long after we move on. You know I believe everyone out there in the universe knows the difference between right and wrong. Weve had our Christ and Mohammed which we payed little heed to and yet we subscribe to the idea of eye for and eye tooth for a tooth life for a life. Imazing how weve made it so far.

Thank you for your time

bob