Kepler has certainly made a lot of discoveries. It should be fairly clear to us now that planetary systems are pretty common and, by extension, sentience must (by sheer odds) be out there too.
But I have to wonder how many assumptions go into this so-called "habitable zone". Doesn't it greatly depend on the atmospheric composition? With a different atmosphere, couldn't Venus be habitable (actually it might be in our Sun's habitable zone)? If Mars were larger, couldn't it support the kind of atmosphere that would allow liquid water.
Particularly if such planets were geologically active.
Even if all this stacks up, at 600 light years away, like pretty much any other star system, this planet is across a gulf I'm not sure we'll ever cross, which is a somewhat depressing thought.
If you look at the diagram for the habitable zone in our own solar system you can see that Nasa would class both Mars and Venus as habitable planets. They already place pretty generous bounds around the habitable zone.
Given the very real possibility that there could have been (still is?) life on mars that makes a lot of sense. (Nasa just sent Curiosity on its way to Mars and one of its main goals is to look for signs of life.)
Still, the only life we currently know of is here on earth. There could be life on Europa, maybe even some other weird places in the solar system but it’s certainly sensible to start with what we know.
Both Venus and Mars have good odds of having had liquid water oceans in the past. From what I understand, Venus would possibly be habitable today if it had a carbon cycle and planetary magnetic field to prevent the runaway greenhouse effect.
it allows to imagine that something could be a "life" in Venus like conditions as well:
"Scientists once thought that no living thing could survive the harsh combination of toxic chemicals, high temperatures, high pressures, and total darkness at these vents. "
"Vent bacteria use hydrogen sulfide as their energy source instead of sunlight. "
Why? Sentience just happens to be an evolutionary trait that was beneficial to us, like wings on a bird.
There millions of species animals on our planet, and only a handful of them are sentient.
We have a bit of a cognitive bias towards thinking that sentient life is something that evolution would work towards, but that isn't really how evolution works.
It's not anthropocentric to assume that sentience will appear elsewhere in the universe, given the sheer number of opportunities for evolution to solve similar problems in similar ways. I expect sentience to exist in other species for the same reason that birds, bats and flying squirrels have convergent adaptations.
Taking this a step further, finding intelligent life out there is simply impossible. The reason our intelligence is unique to only humans on our planet is largely because we defined intelligence as traits that only we possess. We defined it based on our own nature. Finding life out there that would be socially compatible with us is ridiculously unlikely. That life would have had to spring up in an evolutionary environment identical to ours and that's so unlikely that it might as well be impossible.
> Taking this a step further, finding intelligent life out there is simply impossible
What? How can you take this position? That's absolutely crazy. Really, you're going to take observations from just a couple of decades and determine that finding something is "impossible"?!
No way. There's absolutely no way that finding intelligent life is impossible.
> The reason our intelligence is unique to only humans on our planet is largely because we defined intelligence as traits that only we possess
Slow down there. Nobody is looking for "human intelligence" on other planets. Maybe that's why you think it's impossible. I'd say dolphins are intelligent. So are some of our computer systems. There's a lot more intelligence that we can recognize that isn't like ours.
> Finding life out there that would be socially compatible with us is ridiculously unlikely.
I agree. That has nothing to do with intelligence though.
> That life would have had to spring up in an evolutionary environment identical to ours and that's so unlikely that it might as well be impossible.
identical? Sure, nearly impossible. But why bother making it identical? Do you need 20.946% O2 in the atmosphere? Nope! There are probably billions of planets in the Milky Way alone that could support Earth-like life, if we extrapolate from the Kepler mission data.
> Slow down there. Nobody is looking for "human intelligence" on other planets. Maybe that's why you think it's impossible. I'd say dolphins are intelligent. So are some of our computer systems. There's a lot more intelligence that we can recognize that isn't like ours.
When I think of intelligent alien life, I think along the lines of Klingons, not alien dolphins. Are we going to find alien dolphins? Absolutely. Klingons? Nope.
> When I think of intelligent alien life, I think along the lines of Klingons, not alien dolphins. Are we going to find alien dolphins? Absolutely. Klingons? Nope.
Why are you so sure that this is impossible, still? Aside from FTL travel, in what way are humans fundamentally different from Kingons? We both have space travel, some sentience, a taste for weapons, etc.
You think this happened only once in the entire (say) Milky Way, and that there is absolutely 0 chance of it occurring elsewhere? That's certainly possible. But it's not the only possible way things have unfolded.
> Why are you so sure that this is impossible, still? Aside from FTL travel, in what way are humans fundamentally different from Kingons?
You don't understand my argument.
We (and our intelligence) are the unique product of our evolutionary environment. There is no tendency in evolution towards intelligence. There are far many more organisms on this planet in far greater numbers than us that don't even have a brain, nevermind a complex one like ours.
We define intelligence based on traits that we (humans) possess. Some animals possess some of those traits (like dolphins, chimps, etc.), but no animal posses them all, save for us humans, by definition.
For us to find a species that is identical or even just compatible with us psychologically, that species had to evolve in an identical evolutionary environment spanning millions of years. That is so astronomically unlikely that it might as well be impossible.
You may find life that posses some of our traits (like dolphins), but you won't find life that has them all (like Klingons).
Interesting choice of words. So while we're talking in astronomical terms: How big is the universe? How many earth-like planets does it contain? Are there other universes?
Until we can answer at least one of these questions I would refrain from calling anything in this context "astronomically unlikely".
I think that in the whole universe there is intelligent life out there like ours (not in body but in mind/thought). However due to the time/distance scales that are required to interact with them, it might as well not exist, since we'd require a huge amount of luck to ever interact with them.
>There is no tendency in evolution towards intelligence.
What? An obvious ability to learn is found in lots of animals, and in the cases where the benefit outweighs the additional caloric requirements, the evolutionary tendency is towards intelligence. Of course it's not the only one, but it's a pretty big trump card natural selection-wise when it reaches a sufficient level, as humans have clearly demonstrated.
Millions of years are a dime a dozen in the time scales of the universe, and parallelize that across more than trillions of planets. I think your intuition is way off here.
So if some alien spaceship flew up to the planet Earth today, you'd say they aren't intelligent? Just alien dolphins that happen to have built spaceships? What?
I think the point was that some organisms on earth exhibit traits of intelligence, like Dolphins, and that there could be Alien organisms that are like Dolphins that also show signs of intelligence. But just as humans and dolphins on earth cannot live together socially, that intelligence is either too primitive for them to travel to other planets to seek out life alien to them (have you ever seen a Dolphin craft material into a structure that could be used for interplanetary travel?), or is too complex for us to recognize that it is actual intelligence.
Although science fiction has been littered with thousands of stories of alien life visiting us, we humans only know of the fact that humans from Earth are the only organisms looking for life on other planets that we know of. I don't think anyone would doubt that any organism with the capacity to travel to other planets, let alone other solar systems and possibly other galaxies, is un-intelligent. Although we might be biased, we're a pretty intelligent species, as long as the metric is ourselves.
> Nobody is looking for "human intelligence" on other planets. Maybe that's why you think it's impossible. I'd say dolphins are intelligent.
One proviso there is that it'd be very hard to establish that there are dolphins on another planet since the only signature that we have to go on are things that manipulate the light spectrum. We could, perhaps, infer something from an atmospheric condition that we might someday be able to detect, but observe, for instance, how difficult it is for us to determine if there is or has ever been life on Mars, even though it's right next door. For all we know, there could be dolphins on Titan. Sending an exploratory probe that would take millennia to reach its target (and then several hundred years to send data back) will probably remain impractical for an extended period of time.
You cut out the part where I mentioned computer systems when you quoted me. That part was important. It was an attempt to show that there could be radio-communicating, non-human entities with entirely different 'intelligences'.
> will probably remain impractical for an extended period of time.
I don't deny that. I only deny that it's impossible.
> we defined intelligence as traits that only we possess
There's also an article on HN right now about Dolphins proving to be intelligent beings [1]. It says:
Our research has provided an answer to an age-old question highlighted by Dr Jill
Tarter of the SETI Institute, ‘Are we alone?’
We can now unequivocally answer, ‘no.’ SETI’s search for non-human intelligence in
outer spacehas been found right here on earth in the graceful form of dolphins.
I laughed to think that HUMAN'S analysis of whether a dolphin is intelligent is whether WE can understand their language.
Using that logic, it seems my dog is more intelligent than me: He can understand some of my language as well as his own, whereas I can only understand my own.
>I laughed to think that HUMAN'S analysis of whether a dolphin is intelligent is whether WE can understand their language.
>Using that logic, it seems my dog is more intelligent than me: He can understand some of my language as well as his own, whereas I can only understand my own.
That's a false equivalence, as well as untrue.
It takes intentional effort on our part for a dog to learn even a small subset of our vocabulary. When dogs learn our language, they only learn the few words that we make an effort to teach them, and these typically correspond directly to an action we demand of them in exchange for a reward. Dogs cannot pass this knowledge amongst themselves, each dog has to be taught by a human individually.
Dogs have made no specific effort to teach me, at least none that they managed to make recognizable to me, yet I can tell when they are excited, hurt, angry, &c, but mostly because a subset of body language and vocal attitude are instinctive or socially universal to most mammals (shouting and sharp poses convey aggression, for example).
I believe I understand more dog body language than dogs understand human body language. There is no human equivalent of a wagging tail, yet I understand that. There is no dog equivalent of a pointing finger, and they do not understand it: dogs will look at your finger instead of where you point.
I laughed to think that HUMAN'S analysis of whether a dolphin is intelligent is whether WE can understand their language.
Using that logic, it seems my dog is more intelligent than me: He can understand some of my language as well as his own, whereas I can only understand my own.
I agree with your sentiment but your logic is backward. Substitute dog for dolphin in your first sentence:
[a] HUMAN'S analysis of whether a dog is intelligent is whether WE can understand their language.
Since you cannot (by your own admission) understand your dog's language, by the logic of that statement, the dog would not be intelligent.
Therefore, I am not intelligent because I can't get my logic correct. :-)
Actually, I was hoping to slip that one by you guys, because I knew there was something wrong with it.
The point I should have made was that the species that understands less language (us) is considered more intelligent by humans than the one that understands more language (dog). This seems screwed up.
Taken to an extreme, there could be a theoretical species that can communicate among its own kind and understand every other species' communication, and we'd consider it unintelligent because WE can't understand them. That sort of logic makes US seem pretty unintelligent.
There's a fundamental flaw in that argument. Once a sentience, or as i would define it, a species capable of creating technology, exists, it is highly likely to not die out as other traits easily can. It only needs to occur once. One could argue it has -almost- occurred on earth many times, including dolphins, elephants, octopus along with apes right now.
A lot of the more grandiose doom-and-gloom scenarios put forth regarding global warming are a bit overwrought. The Earth will continue to harbor life even if we pumped all of the carbon from every fossil fuel on the planet into the atmosphere. The main issue is that such a world will be different, it may have different species (more of some, less or none of some we've come to know) and it may be more difficult for human civilization to exist. But there's absolutely no risk of human activity re: CO2 emissions in making the Earth uninhabitable.
How can we know if there is life on any planet (close or far) if we can only look for it using our senses? Forget Mars, is it just possible that there is life on earth that we simply cannot know of because we do not have the required senses to perceive it.
Physicalism is essential to science. What sense could we (and our instruments) lack that still exists in the physical world? There is no doubt that there are species we have yet to identify and categorize, but those species will still be made of the same matter that comprises the rest of the universe, detectable by the same means.
The only major obstacle I see to knowing about some form of life on Earth is location -- we can't scan the entire ocean floor, nor can we penetrate into the mantle.
> Sentience just happens to be an evolutionary trait that was beneficial to us ... but that isn't really how evolution works.
Actually that is how evolution works. Evolution results in species acquiring traits that are beneficial to them. Of course you could make a counter-case that perhaps sentience is only beneficial to us in particular, and not so much to other species --
To which I would completely disagree. There is this fascinating, relatively new theory of how humans became sentient. Previously (1960s) it was thought that humans became sentient either somehow out of the blue or due to having to construct tools etc., which then allowed them to organize into groups. The new theory, on the other hand, claims that high intelligence (and by extension sentience) is an inevitable consequence of living within a particular type of group -- largely the type of group that many primates live in (the original studies were done on baboons), though this is not limited to primates.
The idea is that if you are a member of a group where grooming behavior, alliance-making, and status-related interactions are common, you benefit tremendously (in a reproductive sense) from possessing a "theory of mind" capable of making predictions about the actions of others that are at least a few percent more accurate than those of your peers. The way it works is a bit like the stock market -- all you need is to beat the market average. So this "theory of mind" -- being preoccupied with what others think -- is actually claimed to be a runaway effect of the intelligence "arms race" which always occurs among animals living within that type of group. Now, sentience is merely a theory of mind applied to self.
I fully expect that within the next 10 million years at least two other mammal species will become sentient, if we humans don't make them extinct that is... Anyone willing to make a long bet?
I heard theory that there will be no other sentient creatures on Earth because humans will destroy them. I read this theory from article about Birutė Galdikas (http://en.wikipedia.org/wiki/Birut%C4%97_Galdikas) who is studying orangutans. Let's not forget neanderthals as well in this context.
Actually given that dogs score better than chimps, wolves and human infants in tests of social cognition would lend credence to the fact that humans are actually inadvertently creating sentience. Similarly dogs are the only non-primate species to look at the right side of a persons face to gauge their emotion and state, but unlike primates and humans, they don't do this with other species or dogs.
Evidence points to dogs having a limited theory of mind, in that they can actively be deceitful, meaning they can understand the perceptions of other animals.
Not to mention, dogs are already known to have the ability to rationalise, empathise and have abstract learning abilities. They're capable of the whole range of human emotions, including clinical depression, melancholy, anger, rage, etc. Beyond that, they're capable of empathetic sadness and anger. They also display the same ability as many of the great apes to mourn their dead, but notably dead humans.
Orangutans are largely being made extinct for the same reason that humans have made wolves and tried to make numerous other species such as foxes, rabbits, etc. extinct. In that they're pose a risk to our economic livelihoods. Orangutans are dying because of deforestation and poaching.
Wolves evolved into a evolutionary niche as dogs, and as dogs have become as wide spread a species as humans and have evolved far beyond their ancestors. To the point that they actually rank above primates in certain tests of cognition and social behaviour - notably the two behaviours that are attributed as key elements of human evolution to sentience.
Having lived with the "best friends" of humans (cats and dogs) for many years, I am no longer sure what "sentience" is because I find the difference between us and them in everything to be a matter of degree.
We're _better_ at being 'sentient' than they are, but I can't find anything that we do that they don't. I'm serious here. You totally hit the nail on the head when you talk about anger and empathy.
They can learn, they can feel, they can teach their offspring, they can empathize, they can demonstrate their emotional and physical needs, and they can communicate both with us and amongst themselves. They know right from wrong (keeping in mind that in reality there are no moral absolutes and right and wrong very much relative concepts even to humans, and even on what we consider to be an axiomatic basis).
my greatest personal epiphany was when i saw that while we're longing for other intelligence and looking for it out there, there is an other intelligence right near with us.
Just be careful not to project your own humanity onto your pets, if you want to see them more objectively. Radiolab had a great episode on "animal minds" that went into some of the biases dog owners have about their pets. In a sense, we're actually disrespecting other animals by judging them on a scale of "how humanlike is their behavior" and too easily discounting the things that make them unique and unlike us.
I have two dogs, both from the local SPCA. My first was a stray and came to us with full blown anxiety. She used to have separation anxiety from people she'd just met (literally a friend dropped in for 5 minutes just to see her and she spent 20 minutes panicked and crying when he left). However, she's the happiest dog anyone (and I'm really not exaggerating that) has ever seen.
My second dog was abandoned by his owner, completely neglected (skinny, no muscle mass whatsoever, he literally struggled jumping onto a couch, and the SPCA had to shave him almost bald to get rid of the mattes) but that has no effect on the fact that he was depressed and angry over it. When we started training him he became pissy, jumped up on our bed and took a giant shit on it and that's from a 4 year old dog that's never had an accident in our house.
However, the second dog has recently become the bodyguard for the first. We've only had him 3 months, but around other dogs that are overly aggressive in how they tell off another dog (she's barely 2 years old, so a lot of older dogs are very assertive in how they correct her) he has taken to blocking them. He doesn't become aggressive, but when she is nervous or panicked he seems to step in and block, and it's funny because you'll see him for 5 minutes just blocking a dog from getting to her. Even when he gets snarled or snapped at he carries on until the other dog backs off. It's when she submits (rolls on her back, occasionally pees) to other dogs that you see him become angry as he (normally a silent dog) will bark and growl at the other dog and guard her. This happens all the time with our trainers boarder collie (they don't like excitement and our first dog is a jack russell mix, so is basically excitement personified) and there'll be 5 minutes of them squaring off barking at each other and him keeping the trainers dog from our first.
Our first dog knows right from wrong and when she's done wrong. If she knows I've noticed something she's done wrong (like torn up a burger wrapper) she goes into full blown submission and often pees on herself (it's a girl dog way of stopping another dog from attacking her). Our second however either doesn't know or doesn't give a shit about right from wrong.
Crows have the same level of Encephalization Quotient (measure of brain size to body size) as many of the more intelligent mammalian species. They too have complex emotional and social lives, use tools and have complex language. There is even an argument that certain species of crows have co-evolved with us as hunter gatherers the way that dogs did CF - In the Company of Crows and Ravens (John M. Marzluff / Mr. Tony Angell).
Interestingly enough birds are the one group that systemically destroys the sentience tests.
One test, the Mirror Self Recognition test was thought to only be accomplished by humans and the great apes, even monkeys aren't capable (in the traditional sense). However the humble pigeon passes, and not an occasional get lucky pass, but pigeons just nail the test.
Tool use was one of the very classical 'gateways' to sentience argued for humans. Except there appear to be far more bird species than mammal species that regularly use tools. Further than this, Herring Gulls are noted for tool-use hunting by using pieces of bread to hunt goldfish - which essentially one-ups all other known tool users.
Ravens are one of the few species who actually make the toys they play with. IE they don't find a stick and play, but will break twigs off of trees and brushes with the intent of using it to play with others.
There's a series of books by David Brin that explore the idea of "uplift", where humans learn how to augment intelligence in certain animals (dolphins, chimps, and gorillas) and then get busy doing so.
In my opinion, "Startide Rising" and "the Uplift War" are the best books in the series.
That hypothesis can make an interesting read, but if you think about it critically -- it is very unlikely. Suppose humans have already managed to somehow "uplift" dogs (such an assumption would probably go quite well with the many dog owners who are amazed by their pets...). The "uplift" must have happened at least 1000-2000 years ago given that modern dogs are unlikely to be that much smarter than their ancestors from the recorded history. Then, a question arises: if dogs indeed became orders of magnitude smarter than other animals because of their interaction with humans a few thousand years ago, why didn't packs of wild dogs completely dominate wolves, the way Homo sapiens (nearly) completely outcompeted Homo neanderthalensis?
I think the point is that whatever we're doing to domestic animals that makes them appear smart to our eyes is not necessarily what is required of them to appear smart to natural selection if humans were to disappear. In other words, we're not so much "uplifting" domestic animals as molding them to our needs.
Crows are the smartest birds out there, but they are also arguably the most annoying birds out there, and their high intelligence is actually a part of what makes them appear so annoying and pest-like to us (yes, we keep parrots as pets, and parrots are smart also, but in the tropics were parrots are common they cause as much trouble as crows cause here). I think it would be reasonable to conclude that if we ever domesticated crows, the direction that our crow breeds would take would be primarily towards agreeableness to humans even if that came at the expense of intelligence.
I agree that there's a big difference between "domestication" (that we've done with dogs) and breeding for intelligence. I'm not aware that we're doing that with any species (except for maybe Harvard Grads).
Also, one of the conceits of the "Uplift saga" is that genetic engineering tweaks cause most of the "uplift." It's also interesting to note that one of the first species "uplifted" are dolphins, a species that doesn't have much chance to annoy/outcompete humans.
I guess it boils down to how important "intelligence" is to evolutionary adaptation. It apparently conferred significant reproductive benefit to humans (the most populous primate species).
OTOH, to quote J.S.B. Haldane: "the Creator, if he exists, has a inordinate fondness for beetles."
>no other sentient creatures on Earth because humans will destroy them. ... Let's not forget neanderthals as well in this context.
True and false. The most "advanced" humans of any given time have destroyed and will be attempting to destroy the competition. Neandethals fell victim to Cro-Magnon, and the Cro-Magnon [ie. current "humans", we] will in its turn fall victim to the next human species. ( My previous comment http://news.ycombinator.com/item?id=3126716 )
> the Cro-Magnon [ie. current "humans", we] will in its turn fall victim to the next human species.
I don't think so, at least not in a violent way. Like something Nietzsche said in TSZ, "man is something to be surpassed, but only a buffoon thinks that man can be overleapt."
Well, it is really hard to imagine how something/somebody can surpass Cro-Magnon in the ways of violence. On the other side, only violence can keep the Cro-Magnon at bay as Cro-Magnon willn't allow to be peacefully surpassed.
>"but only a buffoon thinks that man can be overleapt"
yep, the 20th century history is littered with such failed over-leap attempts. Curious time we live at - the previous attepts of "leap"-type [necessarily forced] transformations of humans and society are finished and no new is initiated yet. Is it quiet before the storm? I don't believe that we learned the lesson.
The 'habitable zone' is overly simplistic in general. Look at Europa - it's nowhere near the habitable zone, but is one of the most Earth-like plants in our Solar System. That's just inside the one Solar System we have a fairly complete planetary record of!
It also assumes that liquid water and an oxygen atmosphere are prerequisites for life. Extremophiles [1] living on our own planet prove that this is not so.
It also assumes that liquid water and an oxygen atmosphere are prerequisites for life. Extremophiles living on our own planet prove that this is not so.
Maybe this is splitting hairs, but we have evidence that life can exist in such extreme condition. We have no evidence that life can arise under those conditions. I think it's perfectly plausible that it's path-dependent: life needs the friendlier conditions to first develop; once it's up and running with a means of evolving, it's able to acclimatize gradually to the extremes.
If I'm right, then it's still correct to exclude worlds that could never have had the "correct" conditions.
Adding onto this thought, even if life can arise under extreme conditions, the probability of necessary events could still be far lower than the probability of necessary events for life to arise under earth-like conditions.
Thus, the habitable zone criteria is simply narrowing the search space to planets with a high(er) probability of developing and supporting life--while discarding planets with a low(er) probability (though some discarded may indeed have life). It seems reasonable to me in this light, as well.
there is probably more chance of finding intelligent life on planet that is not habitable and can't originate life. because once life becomes "intelligent" it will probably try to colonize more than one "uninhabitable" planet by intelligent machines designed for specific environment.
life needs the friendlier conditions to first develop.
Primitive Life on earth developed on not so friendly environment with poisonous gas (No Oxygen - Oxygen is a byproduct primitive living things created), regular meteor showers and boiling hot waters.
If Life evolved here under these conditions, it can evolve anywhere with such conditions
While I agree "habitable zone" is a bit of a simplification, it really just serves as a starting point for exploration of the galaxy. If we can find thousands of "theoretically habitable" planets, we can pretty much guarantee there are hundreds of thousands of "uniquely habitable planets" like Europa, which we most likely can't detect using our telescopes.
I find these questions interesting too, when the Global Warming group argues that we have to fix it because climate change caused a great die off, one wonders if we're in the 'habitable zone' for our Sun or if we're in the conditionally habitable zone if the planetary chemistry is correct. The latter would seem to both widen what could be habitable, and narrow the probability that somewhere is habitable (have to both be in a zone and chemically appropriate)
As a thought experiment it would be interesting to figure out what it would take to put a satellite in orbit around that planet. One that simply had a plate on it would be fine. Sort of a 'you are not alone' message.
I was thinking more along the lines of "we would be intimidated by it, so we should expect the aliens to react the same way, so don't launch it unless you want a war."
Skipping the "Global Warming" argument all together the Earth very much in a cold spell in the palaeontological sense[0]. It has been much, much warmer for very long periods of time and really only slightly colder. We're far closer to another ice age than we are to the long term average temperature of the planet, let alone its normal maximum temperature. Generally, the warmer periods have given rise to large ecological growth. Maybe human's won't like it, but consider the amount of diversity that would exist with a near rain forest climate across nearly the entire earth.
Backing your statement, I'd further observe of all the terms in the Drake equation, the second term "fraction of stars that have planets" is the second least contentious, only behind the first term "average rate of star formation in the galaxy". I don't think I've ever seen someone claim that life on other planets is rare because planets are rare! It's only the later ones that are contentious. As someone who is so skeptical, showing a huge number of planets doesn't cause me to update my probabilities any, as I already anticipated such a huge number of planets.
What are the odds of there being more than one intelligence in the same galactic neighborhood? Looking at our own planet, which is a biodiversity paradise, there's only one strongly sentient, intelligent, tool-using critter - us.
Why aren't we surrounded by other tool users trying to communicate with us? Why aren't we chatting with dolphins, working with cephalopods, and commuting to work with chimpanzees? Hell, where are the Neanderthals? They're the only other arguably intelligent species that have co-existed at the same time that we did.
And as for time, that's sort of the point of the Fermi paradox, with this much time there should be evidence of life everywhere, unless you have an unstated assumption that all life is self terminating before it reaches a point where it can leave much of a galactic mark? (In our case then, probably excitingly soon)
Charles Stross has pointed out that interstellar travel is probably prohibitively expensive, so any marks left by other civilizations might have been purely local. How many marks have we left? You'd have to do a pretty thorough search of the other planets and moons to find our various landers - hell, it wasn't until last year that anyone took recent pictures of the American moon landing sight, right? A Japanese satellite, if I remember correctly.
Here's a gedankenexperiment for you. Hire a pilot to fly you from Dallas to El Paso. As you're flying over the panhandle, jump out with a parachute. What are the odds that you'll see signs of civilization? I've made that drive before, and if it weren't for the road that I was on, I'd have sworn the planet didn't even have any vertebrates on it.
Obviously my argument is founded on a current understanding of physics, and I'd love to sound like an idiot tomorrow with the invention of cheap interstellar flight and an ansible.
A variation: maybe we're just the first ones in the neighborhood. Maybe life needs elements only present in third generation stars. Earth could be an instance of extremely accelerated evolution because some favorable traits and we are at least some millions of years ahead of the rest.
Maybe the answer to the Fermi paradox is somehow "the singularity". As an intelligent species arises, the amount of time between the emergence of intelligence and a singularity that utterly transforms it into something we would never detect is a blink of the eye geologically. So quickly that it's as if they don't exist to each other.
Pervasive encryption/compression of electromagnetic communication across an extremely wide spectrum and truly badass video games can explain why we haven't been visited and why we can't watch their TV channels.
Planet mass is usually a parameter that we have, even though it does not influence the position of the habitable zone (so Mars is out).
The simplest calculation does not involve an atmosphere and just looks at radiative balance from black body radiation and is probably the kind of calculation they're talking about in the article. For getting the real temperature many parameters play a role and most are not available, so they just use a first guess for the habitable zone.
An atmosphere will change this radiation balance, with absorptive gases and aerosols blocking radiation (both in- and outgoing) and by distributing the heat more evenly. Atmospheres can be detected if the planet's orbit is good, and it is possible to get an idea about the composition (mainly water, methane and CO2 so far), as well as see changes which are probably due to weather. The method used is to look at the center star's light that travelled through the atmosphere of the planet when it traverses; it's also possible to look at the atmosphere's reflection when the planet is almost behind the star. I can go find some spectra if you're interested.
Another important parameter in the equations is albedo ("ability to reflect radiation"). Warmth left from the planet's creation and radioactive decay as well as gravitational effects from other bodies (eg the effect Jupiter has on it's moons) are the other possible energy sources. Geological activity of bigger planets could lead to aurora and allow detection that way, but the instrumentation is not up for that yet..
In our solar system, some moons are considered candidates for life, being covered with a thick layer of ice and possibly containing water underneath and they're not in what is considered the habitable zone of the system. The concept is more of a guideline at this point, really, and also only looks at water (arguably the best candidate for life, but not the only one).
</rant>
In case you want more information about anything in particular I can find some papers or overviews.
I've read this argument a few times and the part I don't follow is how you can figure out the odds for an event (the spontaneous occurrence of life) that has only happened once to our knowledge. For all we know the odds are 1e100 to one.
A planet's chemistry is influenced by it's size, distance from it's star, the the types of supernova that happened in the region where it formed etc. However, I don't think there is going to be all that much differences between basic planet chemistry. Due to basic physics we are never going to find a 'natural' planet that's 95% pure silver. (Someone could presumably make one though.)
The idea of a 'habitable' planet is a cool one, but how relevant is it? Do we really expect that climate is going to be a concern by the time we are colonizing planets 600 light years away?
Now that I think about it, I guess it could be that they are looking for life on other planets and figure that alien life that is recognizable to us will likely be on planets in this zone. I looked at Kepler's mission and they don't really specify why they are looking:
"The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone→ and determine the fraction of the hundreds of billions of stars in our galaxy that might have such planets."
Well, one of the reasons to look is certainly to figure out what kinds of solar systems are typical. Are all solar systems like our solar system? What are the differences? How common are rocky planets? Its mission is to give us a more detailed picture of the solar systems out there.
It’s about knowledge, not whether or not that knowledge is actually useful.
excuse me, yes, I intended to write UN-inhabitable. Its a fear I think is well founded considering global poisoning of air and water, CO2 emissions, uncontrolled population growth and threats to global food production capabilities, and alarming rate of rogue nations with nuclear missiles. Give that another 200 years to take us to the brink. Humans are great at exploration (continents or space), but lousy at stopping or changing their own behavior.
Not that close, since with the fastest vehicles we've ever built, it would take something like a million years to reach even the closest star. If we can figure out how to survive in the harsh environment of space for millennia, it seems like we're pretty much past the need for colonization.
I recommend reading _How to Find a Habitable Planet_.
The first half of the book is about why Earth is habitable, and then it goes to project that against what the search for a similar world requires.
The "snowball earth" scenarios were terrifying (basically, you get an ice ball that is very reflective and thus stays ice, unless you have something like plate tectonics to dirty-up the atmosphere to the point where some insolation can be retained).
I remember when Carl Sagan's "Cosmos" series was first shown on PBS; the episode when the Drake equation was covered was one of my favorite, although even as a teen I understood how small were the chances of finding other sentient life as we hadn't found a single extrasolar planet at the time, let alone in the Goldilocks zone of a star.
Planetary discoveries (like this one) in the past few years are so cool to me.
I love the "Big Bang" episode where Howard raises the topic of the Drake equation. Sheldon immediately rattles it off, first the equation itself, then a rapid-fire explanation of each term in the equation. Sheldon loves that thing. Of course it turns out that Howard has adapted the equation to his own purposes, namely determining how many sentient human females willing and able to mate with Howard exist within the greater Los Angeles metro area.
What's the gravity on the surface? It's 2.4 times the size of earth, is the density the same? If so, that amount of gravity may very well make it uninhabitable.
I'm not sure what we know about this particular planet so far, but I think the part that's missing is volume. Currently, nobody knows what the composition of the planet is. We don't know if it's liquid or solid, for example. I think.
Orbit size and speed have no relation to planetary density by themselves. If we knew the total kinetic energy of the planet, then they would, but we don't.
We don't have "f-star"; the centripedal force (or the force of gravity in this case) is the product of both the mass of the star and the mass of the planet, which we don't have.
Humans can withstand much more than 2.4Gs although the time is exponentially and inversely proportional (for example, 3Gs is a space shuttle launch for a number of minutes, 10Gs is the maximum force allowed during space capsule landing, but only for a few seconds).
Therefore, I wouldn't say "uninhabitable," but probably less friendly (and not immediately lethal) to humans. Also, different animals have different thresholds -- mice, for example, have a much lower tolerance for G-forces than whales.
I recommend reading "Packing for Mars" by Mary Roach -- very insightful book that discusses all sorts of things about planet habitability, space travel, space suit design, psychology, and among many other things, G-forces.
That's curious... I would have thought a land-dwelling mouse would have more G-force tolerance than a whale living in neutral buoyancy oceans. Are you using that as an illustrative example (eg. mice and elephants), or does that still hold for mice and whales?
You're right, it was a bad example. I just looked through the book I referenced, this is what it said (p. 126):
"...a beached whale will die from an overdose of gravity... The whale's diaphragm and rib muscles aren't strong enough to expand its lungs and raise the now far heavier blubber and bone that press in on them, and the animal suffocates."
It goes on:
"You can see what a rat's organs look like inside its body at 10 G's and 19 G's [in] the February 1953 issue of Aviation Medicine... Anesthetized rats were immersed in liquid nitrogen while riding a centrifuge... Heavier blood in the heart has pooled at the bottom of the organ and weighed it down, elongating it like a wad of stretched Silly Putty... This is why the astronauts lie down during reentry -- so the blood doesn't pool in their legs and feet"
I wish I could say I was using it as an illustrative example... But I just remembered it wrong :)
"only", heh (BTW, it's 12 linear degrees, 105 square degrees)
It's hard to make instruments that provide good images across wide angles. Many visual telescopes, both amateur and professional, stay at 1 degree and less of true field of view for medium and high magnification; 2 degrees true field is already pretty good and it's usually obtained at low magnification.
Astrographs can produce wider fields of view, 10 degrees being considered pretty studly, to borrow a quote from Linus. But normally you don't get that "for free". You force an optical element to work at such a wide angle, and then correct the inevitable distortions with various correctors, which are usually lenses or combinations thereof.
The Kepler mission is essentially a Schmidt camera, an old, true and tested design:
Its almost 1 meter aperture would allow a theoretical resolving power of almost 0.1 arcsec (which is my full height as an average guy, standing in Los Angeles, as seen from New York), which could be exploited freely in space since there's no atmosphere to reduce it. Unfortunately, for the type of measurements they do, the image is softened intentionally back to 10 arcsec, which is the theoretical resolution of a 1 cm aperture, or the lens in your digital camera (assuming your camera is a true diffraction-limited system, which it very likely isn't). However, the light gathering power of Kepler is, of course, 10k greater than your camera's; and, again, it's unimpeded by messy and light-polluted Earth atmosphere.
Sorry for the pop-sci journalism comparisons, but the numbers really are kind of mind-boggling.
Please note the curved sensor array, which is due to the fact that a Schmidt scope actually does have a curved field (the light comes to true focus not in a plane, but in a segment of sphere). In fact, flat fields are something you strive for, you don't get for free; even common types of instruments have curved fields, but in most cases the radius of curvature is so big you can ignore it.
It's actually funny the way I made the mistake; things got flipped at a semantic level, above syntax. I guess a neuroscientist would see some significance in it, or something.
All these comments are fun conjecture, but no one commenting (or on this planet) will be able to reasonably assume anything regarding life or sentience on other planets based on our utter lack of data. There may be life that exists outside of 'habitable' zones. There may be several different types of 'intelligence' that may or may not match our own. No one here can definitively claim that anything is or should be with so many possibilities.
Our only frame of reference is this planet, and while diverse, doesn't represent steadfast laws that all life in the universe follow (convergence, carbon-based, etc.). These questions will only be answered when we send probes, people, or find some other way of observing these planets directly.
So what we are seeing now are the light that came out the planet when Lorenzo Di Medici was inventing capitalism and financing the renaissance in Italy in 15th century.
Sometimes us history buffs get laughs out of these things. I was listening to a Catholic thinker make a case for the uniqueness of Earth, and what came to my mind was how Augustine accepted the possibility of other continents and how the world was round, but concluded based on the Bible that humans could not possibly be inhabiting anywhere beyond Asia, Africa, and Europe. This view remained the standard view until after it became clear that Columbus had in fact not reached Asia but instead a new continent, and that it was INHABITED.
I wonder how much theology of so many people will have to be discarded or rethought as we find more reason to think there are inhabited planets elsewhere in the universe.
US is financially fledgling and we're pumping over $20B/year into this behemoth money pit called NASA to tell us there is another Earth we'll never get to. We can barely get to Mars!
119 comments
[ 220 ms ] story [ 457 ms ] threadBut I have to wonder how many assumptions go into this so-called "habitable zone". Doesn't it greatly depend on the atmospheric composition? With a different atmosphere, couldn't Venus be habitable (actually it might be in our Sun's habitable zone)? If Mars were larger, couldn't it support the kind of atmosphere that would allow liquid water.
Particularly if such planets were geologically active.
Even if all this stacks up, at 600 light years away, like pretty much any other star system, this planet is across a gulf I'm not sure we'll ever cross, which is a somewhat depressing thought.
Given the very real possibility that there could have been (still is?) life on mars that makes a lot of sense. (Nasa just sent Curiosity on its way to Mars and one of its main goals is to look for signs of life.)
Still, the only life we currently know of is here on earth. There could be life on Europa, maybe even some other weird places in the solar system but it’s certainly sensible to start with what we know.
"Scientists once thought that no living thing could survive the harsh combination of toxic chemicals, high temperatures, high pressures, and total darkness at these vents. "
"Vent bacteria use hydrogen sulfide as their energy source instead of sunlight. "
http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/HTML/ps_vents.html
Why? Sentience just happens to be an evolutionary trait that was beneficial to us, like wings on a bird.
There millions of species animals on our planet, and only a handful of them are sentient.
We have a bit of a cognitive bias towards thinking that sentient life is something that evolution would work towards, but that isn't really how evolution works.
It also didn't take very long in cosmological terms for humans to go from sentient to supercomputers, either.
Taking this a step further, finding intelligent life out there is simply impossible. The reason our intelligence is unique to only humans on our planet is largely because we defined intelligence as traits that only we possess. We defined it based on our own nature. Finding life out there that would be socially compatible with us is ridiculously unlikely. That life would have had to spring up in an evolutionary environment identical to ours and that's so unlikely that it might as well be impossible.
What? How can you take this position? That's absolutely crazy. Really, you're going to take observations from just a couple of decades and determine that finding something is "impossible"?!
No way. There's absolutely no way that finding intelligent life is impossible.
> The reason our intelligence is unique to only humans on our planet is largely because we defined intelligence as traits that only we possess
Slow down there. Nobody is looking for "human intelligence" on other planets. Maybe that's why you think it's impossible. I'd say dolphins are intelligent. So are some of our computer systems. There's a lot more intelligence that we can recognize that isn't like ours.
> Finding life out there that would be socially compatible with us is ridiculously unlikely.
I agree. That has nothing to do with intelligence though.
> That life would have had to spring up in an evolutionary environment identical to ours and that's so unlikely that it might as well be impossible.
identical? Sure, nearly impossible. But why bother making it identical? Do you need 20.946% O2 in the atmosphere? Nope! There are probably billions of planets in the Milky Way alone that could support Earth-like life, if we extrapolate from the Kepler mission data.
The chances are better than you might think.
When I think of intelligent alien life, I think along the lines of Klingons, not alien dolphins. Are we going to find alien dolphins? Absolutely. Klingons? Nope.
Why are you so sure that this is impossible, still? Aside from FTL travel, in what way are humans fundamentally different from Kingons? We both have space travel, some sentience, a taste for weapons, etc.
You think this happened only once in the entire (say) Milky Way, and that there is absolutely 0 chance of it occurring elsewhere? That's certainly possible. But it's not the only possible way things have unfolded.
You don't understand my argument.
We (and our intelligence) are the unique product of our evolutionary environment. There is no tendency in evolution towards intelligence. There are far many more organisms on this planet in far greater numbers than us that don't even have a brain, nevermind a complex one like ours.
We define intelligence based on traits that we (humans) possess. Some animals possess some of those traits (like dolphins, chimps, etc.), but no animal posses them all, save for us humans, by definition.
For us to find a species that is identical or even just compatible with us psychologically, that species had to evolve in an identical evolutionary environment spanning millions of years. That is so astronomically unlikely that it might as well be impossible.
You may find life that posses some of our traits (like dolphins), but you won't find life that has them all (like Klingons).
Interesting choice of words. So while we're talking in astronomical terms: How big is the universe? How many earth-like planets does it contain? Are there other universes?
Until we can answer at least one of these questions I would refrain from calling anything in this context "astronomically unlikely".
What? An obvious ability to learn is found in lots of animals, and in the cases where the benefit outweighs the additional caloric requirements, the evolutionary tendency is towards intelligence. Of course it's not the only one, but it's a pretty big trump card natural selection-wise when it reaches a sufficient level, as humans have clearly demonstrated.
Millions of years are a dime a dozen in the time scales of the universe, and parallelize that across more than trillions of planets. I think your intuition is way off here.
I don't even know what you are arguing against.
Although science fiction has been littered with thousands of stories of alien life visiting us, we humans only know of the fact that humans from Earth are the only organisms looking for life on other planets that we know of. I don't think anyone would doubt that any organism with the capacity to travel to other planets, let alone other solar systems and possibly other galaxies, is un-intelligent. Although we might be biased, we're a pretty intelligent species, as long as the metric is ourselves.
One proviso there is that it'd be very hard to establish that there are dolphins on another planet since the only signature that we have to go on are things that manipulate the light spectrum. We could, perhaps, infer something from an atmospheric condition that we might someday be able to detect, but observe, for instance, how difficult it is for us to determine if there is or has ever been life on Mars, even though it's right next door. For all we know, there could be dolphins on Titan. Sending an exploratory probe that would take millennia to reach its target (and then several hundred years to send data back) will probably remain impractical for an extended period of time.
> will probably remain impractical for an extended period of time.
I don't deny that. I only deny that it's impossible.
There's also an article on HN right now about Dolphins proving to be intelligent beings [1]. It says:
I laughed to think that HUMAN'S analysis of whether a dolphin is intelligent is whether WE can understand their language.Using that logic, it seems my dog is more intelligent than me: He can understand some of my language as well as his own, whereas I can only understand my own.
--
[1] http://wakeup-world.com//2011/11/28/the-discovery-of-dolphin...
>Using that logic, it seems my dog is more intelligent than me: He can understand some of my language as well as his own, whereas I can only understand my own.
That's a false equivalence, as well as untrue.
It takes intentional effort on our part for a dog to learn even a small subset of our vocabulary. When dogs learn our language, they only learn the few words that we make an effort to teach them, and these typically correspond directly to an action we demand of them in exchange for a reward. Dogs cannot pass this knowledge amongst themselves, each dog has to be taught by a human individually.
Dogs have made no specific effort to teach me, at least none that they managed to make recognizable to me, yet I can tell when they are excited, hurt, angry, &c, but mostly because a subset of body language and vocal attitude are instinctive or socially universal to most mammals (shouting and sharp poses convey aggression, for example).
I believe I understand more dog body language than dogs understand human body language. There is no human equivalent of a wagging tail, yet I understand that. There is no dog equivalent of a pointing finger, and they do not understand it: dogs will look at your finger instead of where you point.
Using that logic, it seems my dog is more intelligent than me: He can understand some of my language as well as his own, whereas I can only understand my own.
I agree with your sentiment but your logic is backward. Substitute dog for dolphin in your first sentence:
[a] HUMAN'S analysis of whether a dog is intelligent is whether WE can understand their language.
Since you cannot (by your own admission) understand your dog's language, by the logic of that statement, the dog would not be intelligent.
Actually, I was hoping to slip that one by you guys, because I knew there was something wrong with it.
The point I should have made was that the species that understands less language (us) is considered more intelligent by humans than the one that understands more language (dog). This seems screwed up.
Taken to an extreme, there could be a theoretical species that can communicate among its own kind and understand every other species' communication, and we'd consider it unintelligent because WE can't understand them. That sort of logic makes US seem pretty unintelligent.
The only major obstacle I see to knowing about some form of life on Earth is location -- we can't scan the entire ocean floor, nor can we penetrate into the mantle.
man, that plugs nicely into the whole dark matter/energy discussion.
Actually that is how evolution works. Evolution results in species acquiring traits that are beneficial to them. Of course you could make a counter-case that perhaps sentience is only beneficial to us in particular, and not so much to other species --
To which I would completely disagree. There is this fascinating, relatively new theory of how humans became sentient. Previously (1960s) it was thought that humans became sentient either somehow out of the blue or due to having to construct tools etc., which then allowed them to organize into groups. The new theory, on the other hand, claims that high intelligence (and by extension sentience) is an inevitable consequence of living within a particular type of group -- largely the type of group that many primates live in (the original studies were done on baboons), though this is not limited to primates.
The idea is that if you are a member of a group where grooming behavior, alliance-making, and status-related interactions are common, you benefit tremendously (in a reproductive sense) from possessing a "theory of mind" capable of making predictions about the actions of others that are at least a few percent more accurate than those of your peers. The way it works is a bit like the stock market -- all you need is to beat the market average. So this "theory of mind" -- being preoccupied with what others think -- is actually claimed to be a runaway effect of the intelligence "arms race" which always occurs among animals living within that type of group. Now, sentience is merely a theory of mind applied to self.
I fully expect that within the next 10 million years at least two other mammal species will become sentient, if we humans don't make them extinct that is... Anyone willing to make a long bet?
Thus perpetuating the false notion that sentience is only beneficial to Homo sapiens. Oh, the irony.
Evidence points to dogs having a limited theory of mind, in that they can actively be deceitful, meaning they can understand the perceptions of other animals.
Not to mention, dogs are already known to have the ability to rationalise, empathise and have abstract learning abilities. They're capable of the whole range of human emotions, including clinical depression, melancholy, anger, rage, etc. Beyond that, they're capable of empathetic sadness and anger. They also display the same ability as many of the great apes to mourn their dead, but notably dead humans.
Orangutans are largely being made extinct for the same reason that humans have made wolves and tried to make numerous other species such as foxes, rabbits, etc. extinct. In that they're pose a risk to our economic livelihoods. Orangutans are dying because of deforestation and poaching.
Wolves evolved into a evolutionary niche as dogs, and as dogs have become as wide spread a species as humans and have evolved far beyond their ancestors. To the point that they actually rank above primates in certain tests of cognition and social behaviour - notably the two behaviours that are attributed as key elements of human evolution to sentience.
We're _better_ at being 'sentient' than they are, but I can't find anything that we do that they don't. I'm serious here. You totally hit the nail on the head when you talk about anger and empathy.
They can learn, they can feel, they can teach their offspring, they can empathize, they can demonstrate their emotional and physical needs, and they can communicate both with us and amongst themselves. They know right from wrong (keeping in mind that in reality there are no moral absolutes and right and wrong very much relative concepts even to humans, and even on what we consider to be an axiomatic basis).
What's left? I honestly would like to know.
on related note: http://news.ycombinator.com/item?id=2666839
My second dog was abandoned by his owner, completely neglected (skinny, no muscle mass whatsoever, he literally struggled jumping onto a couch, and the SPCA had to shave him almost bald to get rid of the mattes) but that has no effect on the fact that he was depressed and angry over it. When we started training him he became pissy, jumped up on our bed and took a giant shit on it and that's from a 4 year old dog that's never had an accident in our house.
However, the second dog has recently become the bodyguard for the first. We've only had him 3 months, but around other dogs that are overly aggressive in how they tell off another dog (she's barely 2 years old, so a lot of older dogs are very assertive in how they correct her) he has taken to blocking them. He doesn't become aggressive, but when she is nervous or panicked he seems to step in and block, and it's funny because you'll see him for 5 minutes just blocking a dog from getting to her. Even when he gets snarled or snapped at he carries on until the other dog backs off. It's when she submits (rolls on her back, occasionally pees) to other dogs that you see him become angry as he (normally a silent dog) will bark and growl at the other dog and guard her. This happens all the time with our trainers boarder collie (they don't like excitement and our first dog is a jack russell mix, so is basically excitement personified) and there'll be 5 minutes of them squaring off barking at each other and him keeping the trainers dog from our first.
Our first dog knows right from wrong and when she's done wrong. If she knows I've noticed something she's done wrong (like torn up a burger wrapper) she goes into full blown submission and often pees on herself (it's a girl dog way of stopping another dog from attacking her). Our second however either doesn't know or doesn't give a shit about right from wrong.
Yes, I like crows :)
One test, the Mirror Self Recognition test was thought to only be accomplished by humans and the great apes, even monkeys aren't capable (in the traditional sense). However the humble pigeon passes, and not an occasional get lucky pass, but pigeons just nail the test.
Tool use was one of the very classical 'gateways' to sentience argued for humans. Except there appear to be far more bird species than mammal species that regularly use tools. Further than this, Herring Gulls are noted for tool-use hunting by using pieces of bread to hunt goldfish - which essentially one-ups all other known tool users.
Ravens are one of the few species who actually make the toys they play with. IE they don't find a stick and play, but will break twigs off of trees and brushes with the intent of using it to play with others.
In my opinion, "Startide Rising" and "the Uplift War" are the best books in the series.
I think the point is that whatever we're doing to domestic animals that makes them appear smart to our eyes is not necessarily what is required of them to appear smart to natural selection if humans were to disappear. In other words, we're not so much "uplifting" domestic animals as molding them to our needs.
Crows are the smartest birds out there, but they are also arguably the most annoying birds out there, and their high intelligence is actually a part of what makes them appear so annoying and pest-like to us (yes, we keep parrots as pets, and parrots are smart also, but in the tropics were parrots are common they cause as much trouble as crows cause here). I think it would be reasonable to conclude that if we ever domesticated crows, the direction that our crow breeds would take would be primarily towards agreeableness to humans even if that came at the expense of intelligence.
Also, one of the conceits of the "Uplift saga" is that genetic engineering tweaks cause most of the "uplift." It's also interesting to note that one of the first species "uplifted" are dolphins, a species that doesn't have much chance to annoy/outcompete humans.
I guess it boils down to how important "intelligence" is to evolutionary adaptation. It apparently conferred significant reproductive benefit to humans (the most populous primate species).
OTOH, to quote J.S.B. Haldane: "the Creator, if he exists, has a inordinate fondness for beetles."
True and false. The most "advanced" humans of any given time have destroyed and will be attempting to destroy the competition. Neandethals fell victim to Cro-Magnon, and the Cro-Magnon [ie. current "humans", we] will in its turn fall victim to the next human species. ( My previous comment http://news.ycombinator.com/item?id=3126716 )
I don't think so, at least not in a violent way. Like something Nietzsche said in TSZ, "man is something to be surpassed, but only a buffoon thinks that man can be overleapt."
Well, it is really hard to imagine how something/somebody can surpass Cro-Magnon in the ways of violence. On the other side, only violence can keep the Cro-Magnon at bay as Cro-Magnon willn't allow to be peacefully surpassed.
>"but only a buffoon thinks that man can be overleapt"
yep, the 20th century history is littered with such failed over-leap attempts. Curious time we live at - the previous attepts of "leap"-type [necessarily forced] transformations of humans and society are finished and no new is initiated yet. Is it quiet before the storm? I don't believe that we learned the lesson.
It also assumes that liquid water and an oxygen atmosphere are prerequisites for life. Extremophiles [1] living on our own planet prove that this is not so.
[1] http://en.wikipedia.org/wiki/Extremophile
Maybe this is splitting hairs, but we have evidence that life can exist in such extreme condition. We have no evidence that life can arise under those conditions. I think it's perfectly plausible that it's path-dependent: life needs the friendlier conditions to first develop; once it's up and running with a means of evolving, it's able to acclimatize gradually to the extremes.
If I'm right, then it's still correct to exclude worlds that could never have had the "correct" conditions.
Thus, the habitable zone criteria is simply narrowing the search space to planets with a high(er) probability of developing and supporting life--while discarding planets with a low(er) probability (though some discarded may indeed have life). It seems reasonable to me in this light, as well.
Primitive Life on earth developed on not so friendly environment with poisonous gas (No Oxygen - Oxygen is a byproduct primitive living things created), regular meteor showers and boiling hot waters.
If Life evolved here under these conditions, it can evolve anywhere with such conditions
Low hanging fruit first.
As a thought experiment it would be interesting to figure out what it would take to put a satellite in orbit around that planet. One that simply had a plate on it would be fine. Sort of a 'you are not alone' message.
[1] https://en.wikipedia.org/wiki/Eon_%28novel%29
Note: the horizontal scale is VERY awkward [0]http://upload.wikimedia.org/wikipedia/commons/thumb/f/f5/All...
... and your solution to the Fermi paradox is?
What are the odds of there being more than one intelligence in the same galactic neighborhood? Looking at our own planet, which is a biodiversity paradise, there's only one strongly sentient, intelligent, tool-using critter - us.
Why aren't we surrounded by other tool users trying to communicate with us? Why aren't we chatting with dolphins, working with cephalopods, and commuting to work with chimpanzees? Hell, where are the Neanderthals? They're the only other arguably intelligent species that have co-existed at the same time that we did.
It's a big universe, and it's a big timeline.
Ironic you should say: from HN this morning: Researchers 'speak' to dolphins in their own language http://news.ycombinator.com/item?id=3314056
:)
And as for time, that's sort of the point of the Fermi paradox, with this much time there should be evidence of life everywhere, unless you have an unstated assumption that all life is self terminating before it reaches a point where it can leave much of a galactic mark? (In our case then, probably excitingly soon)
Here's a gedankenexperiment for you. Hire a pilot to fly you from Dallas to El Paso. As you're flying over the panhandle, jump out with a parachute. What are the odds that you'll see signs of civilization? I've made that drive before, and if it weren't for the road that I was on, I'd have sworn the planet didn't even have any vertebrates on it.
Obviously my argument is founded on a current understanding of physics, and I'd love to sound like an idiot tomorrow with the invention of cheap interstellar flight and an ansible.
The simplest calculation does not involve an atmosphere and just looks at radiative balance from black body radiation and is probably the kind of calculation they're talking about in the article. For getting the real temperature many parameters play a role and most are not available, so they just use a first guess for the habitable zone.
An atmosphere will change this radiation balance, with absorptive gases and aerosols blocking radiation (both in- and outgoing) and by distributing the heat more evenly. Atmospheres can be detected if the planet's orbit is good, and it is possible to get an idea about the composition (mainly water, methane and CO2 so far), as well as see changes which are probably due to weather. The method used is to look at the center star's light that travelled through the atmosphere of the planet when it traverses; it's also possible to look at the atmosphere's reflection when the planet is almost behind the star. I can go find some spectra if you're interested.
Another important parameter in the equations is albedo ("ability to reflect radiation"). Warmth left from the planet's creation and radioactive decay as well as gravitational effects from other bodies (eg the effect Jupiter has on it's moons) are the other possible energy sources. Geological activity of bigger planets could lead to aurora and allow detection that way, but the instrumentation is not up for that yet..
In our solar system, some moons are considered candidates for life, being covered with a thick layer of ice and possibly containing water underneath and they're not in what is considered the habitable zone of the system. The concept is more of a guideline at this point, really, and also only looks at water (arguably the best candidate for life, but not the only one).
</rant> In case you want more information about anything in particular I can find some papers or overviews.
Now that I think about it, I guess it could be that they are looking for life on other planets and figure that alien life that is recognizable to us will likely be on planets in this zone. I looked at Kepler's mission and they don't really specify why they are looking:
"The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone→ and determine the fraction of the hundreds of billions of stars in our galaxy that might have such planets."
It’s about knowledge, not whether or not that knowledge is actually useful.
I don't think our planet is going to become uninhabitable, not by a long shot.
Scientists believe this will happen in billions of years, but it could happen tomorrow.
I'm pretty sure that statement flies in the face of astrophysics.
The first half of the book is about why Earth is habitable, and then it goes to project that against what the search for a similar world requires.
The "snowball earth" scenarios were terrifying (basically, you get an ice ball that is very reflective and thus stays ice, unless you have something like plate tectonics to dirty-up the atmosphere to the point where some insolation can be retained).
Planetary discoveries (like this one) in the past few years are so cool to me.
http://en.wikipedia.org/wiki/Centripetal_force#Formula
We have: r, v, m-star, f-star - so m-planet follows right?
Therefore, I wouldn't say "uninhabitable," but probably less friendly (and not immediately lethal) to humans. Also, different animals have different thresholds -- mice, for example, have a much lower tolerance for G-forces than whales.
I recommend reading "Packing for Mars" by Mary Roach -- very insightful book that discusses all sorts of things about planet habitability, space travel, space suit design, psychology, and among many other things, G-forces.
"...a beached whale will die from an overdose of gravity... The whale's diaphragm and rib muscles aren't strong enough to expand its lungs and raise the now far heavier blubber and bone that press in on them, and the animal suffocates."
It goes on:
"You can see what a rat's organs look like inside its body at 10 G's and 19 G's [in] the February 1953 issue of Aviation Medicine... Anesthetized rats were immersed in liquid nitrogen while riding a centrifuge... Heavier blood in the heart has pooled at the bottom of the organ and weighed it down, elongating it like a wad of stretched Silly Putty... This is why the astronauts lie down during reentry -- so the blood doesn't pool in their legs and feet"
I wish I could say I was using it as an illustrative example... But I just remembered it wrong :)
http://en.wikipedia.org/wiki/Kepler_(spacecraft)
you will find out that:
- it has 42 sensors with 95 MPixel resolution total
- they only cover 10 square degrees of sky
- only 150k stars were selected for monitoring the rest of the pixels is thrown out
- they are read out every six seconds and every 30mins the pictures are combined and stored
- it sits on an orbit similar to Earth's, trailing it somewhat
- it can communicate with the mission center in Boulder at 4.3Mb/s in bursts of ~100Gbits
- it has a 16GB SSD
- from the frequency of finding planets somebody estimated that there are 2 billions of Earth-like planets in our galaxy and 6 sextillions in total :)
"only", heh (BTW, it's 12 linear degrees, 105 square degrees)
It's hard to make instruments that provide good images across wide angles. Many visual telescopes, both amateur and professional, stay at 1 degree and less of true field of view for medium and high magnification; 2 degrees true field is already pretty good and it's usually obtained at low magnification.
Astrographs can produce wider fields of view, 10 degrees being considered pretty studly, to borrow a quote from Linus. But normally you don't get that "for free". You force an optical element to work at such a wide angle, and then correct the inevitable distortions with various correctors, which are usually lenses or combinations thereof.
The Kepler mission is essentially a Schmidt camera, an old, true and tested design:
http://en.wikipedia.org/wiki/Schmidt_camera
Its almost 1 meter aperture would allow a theoretical resolving power of almost 0.1 arcsec (which is my full height as an average guy, standing in Los Angeles, as seen from New York), which could be exploited freely in space since there's no atmosphere to reduce it. Unfortunately, for the type of measurements they do, the image is softened intentionally back to 10 arcsec, which is the theoretical resolution of a 1 cm aperture, or the lens in your digital camera (assuming your camera is a true diffraction-limited system, which it very likely isn't). However, the light gathering power of Kepler is, of course, 10k greater than your camera's; and, again, it's unimpeded by messy and light-polluted Earth atmosphere.
Sorry for the pop-sci journalism comparisons, but the numbers really are kind of mind-boggling.
http://kepler.nasa.gov/Mission/QuickGuide/MissionDesign/Phot...
Please note the curved sensor array, which is due to the fact that a Schmidt scope actually does have a curved field (the light comes to true focus not in a plane, but in a segment of sphere). In fact, flat fields are something you strive for, you don't get for free; even common types of instruments have curved fields, but in most cases the radius of curvature is so big you can ignore it.
Optical instruments are tricksy.
> 0.1 arcsec, or 6 arcmin
I'm pretty sure 0.1 arcsec isn't 6 arcmin :) it's less than 0.002 arcmin
It's actually funny the way I made the mistake; things got flipped at a semantic level, above syntax. I guess a neuroscientist would see some significance in it, or something.
Our only frame of reference is this planet, and while diverse, doesn't represent steadfast laws that all life in the universe follow (convergence, carbon-based, etc.). These questions will only be answered when we send probes, people, or find some other way of observing these planets directly.
Please forgive my total field ignorance and educate me.
So what we are seeing now are the light that came out the planet when Lorenzo Di Medici was inventing capitalism and financing the renaissance in Italy in 15th century.
Not very good chances we'll get there soon.
Yes, I know it's impossibly far away. I just find it harder to get excited about this these days. And yes, I know that's not totally rational.
But yeah, what cletus said. Depressing.
I wonder how much theology of so many people will have to be discarded or rethought as we find more reason to think there are inhabited planets elsewhere in the universe.
US is financially fledgling and we're pumping over $20B/year into this behemoth money pit called NASA to tell us there is another Earth we'll never get to. We can barely get to Mars!
Let's focus on problems here!