We shouldn’t think of deliberately yelling before we can do it from relay station 10 light-years out, that is programmed to vaporize itself if Berserkers show up.
Here’s a very narrow criticism: There are only 9 known stellar systems within 10 light years of Earth, and three of those are unlikely sources of intelligent life (Sirius and two recently found brown dwarf systems). I believe that distribution is typical for our part of the galaxy, and if so, ten light years out for a relay station won’t do much to disguise our true location – the sun will stand out as a likely nearby candidate.
A more broad criticism: none of these considerations matter because we’re detectable via telescope from thousands of light years away. Google “FOCAL” and “Maccone” and optionally “centauri-dreams” to read about one such approach.
It’s a little late for that. Our first radio signals are now over 100 light years out and the first TV broadcast signals are nearly 80 light years out, and both still spreading at the speed of light.
A considerable number of those TV and radio broadcasts are stories about Earth defeating alien invaders who have vastly superior technology and the element of surprise. We’re not just shouting, we’re shouting “come and have a go if you think you’re hard enough!”
And pretty hard to detect at that distance. The SETI institute thinks that we’d unable detect ordinary radio and television from the closest star, and even with superior technology they’d be drowned out by background noise at some distance.
Brin is much more worried about a deliberate Yoohoo from a big radar dish,, or a lucky intercept of us using a big radar to look at, for example, an asteroid.
4. If aliens are near enough for us to get a response within centuries, then there are at least thousands of them out there that could yell or otherwise make themselves visible. But all of them instead seem to keep quiet and hide. That seems worrisome.
This strikes me as a learned behavior. How might it come about?
As pointed out, we’ve been shouting so that cats out of the bag. But a response from aggressive aliens would take time during which me might have colonies perhaps to near stars. Those other aliens that are silent would either have seen their home world wiped out or… didn’t survive to see it. Either way, silence.
If anyone has done an estimate of the RF power radiated by earth vs astronomical distances e.g 100+ light years – while taking into account space plasma distortions and the S/N relationship for galactic RF noise sources and quantum detectibility limits, please publish it here. I’m too frikken lazy to do it myself.
Thanx!
I haven’t done the math either, but a rough approximation in human terms is listening for someone whistling at an AC/DC concert. The music is loud, the crowd is loud, but you can still hear a whistle: a high intensity burst at a different frequency than the background. More detailed communication, say listening to someone talking two rows back, is far more difficult.
Right, basically integrating out the white noise while the tight bandwidth signal builds over time into something detectable. OTOH, if there are random walk noise processes – say varying large phase shifts and multipath due to parsecs of variously magnetized plasma, then the signal will get “smeared out” somewhat. So I guess the problem is how far out do you have to go and how much junk gets in the way such that the integration time is large in relation to the life span of an extra terrestrial SETI program? No doubt there’s a book someplace.
I’m appalled!
This “shut up” idea is disgustingly culturally insensitive, and thus shouldn’t be discussed, let alone suggested or implemented!
After all, we must value multiculturalism, and doing so means that we must, inherently, regard all cultures as equal – and with equal prerogatives. Thus, if there is an xenophobic genocidal alien culture out there that would exterminate us, that’s not wrong, it’s just part of their culture… and who are we to hinder them (via hiding) from freely practicing their culture wherever they see fit?
You left out the part about us polluting the galaxy’s precious electromagnetic waves with our signals.
After all, we’re just a planet of old white men and deserve to be destroyed before we contaminate the solar system with life that isn’t organically grown…
…Oh …that’s why colonization will cost 100’s of billions!.
It really is the ultimate hubris to think any truly advanced alien civilization would be interested in us. To what possible advantage (to them) would that be? Arthur C. Clarke compares SETI to like talking with your dog. You can do it, but it’s a pretty one sided conversation and you don’t keep it up for very long. Nor am I worried about marauding, malevolent, not so advanced aliens. The universe is very very old. As Arthur C. Clarke also has pointed out, any truly malignant, malevolent and violent civilization would have extinguished itself from existence long, long before it gets to us. Nuclear proliferation is just one very very small example of this principle. Now if that civilization were on the next planet, that might be a different story! Looks like we lucked out!
They may not be interested in us, but knowing we exist may point them in the direction of a nice fixer upper water planet.
We might extinguish ourselves, but with starflight they may only extinguish a home world here and there making earth even more valuable (supply and demand.)
Why would they find Earth attractive? We can only live here and now, or in a colony which we create. A few hundred million years ago we couldn’t survive on Earth because there wouldn’t be enough oxygen in the atmosphere and maybe nothing here which we could eat. And actually, we are co-evolving together with our microbes on even shorter timescales.
Why would they find Earth attractive?
Are you not from here?
“As Arthur C. Clarke also has pointed out, any truly malignant, malevolent and violent civilization would have extinguished itself from existence long, long before it gets to us.”
One hopes…
As Arthur C. Clarke also has pointed out, any truly malignant, malevolent and violent civilization would have extinguished itself from existence long, long before it gets to us.
Written during the height of MAD of course, just as “War of the Worlds” reflected the imperialist state of the world at the time by one of Clark’s predecessors. What “advanced” civilizations will actually be like is as unknowable as the scientific landscape of X years in the future. Following Well’s and Clark’s example though, I’d hypothesize a race of busybody nihilists looking to transform this planet’s inhabitants into beings worthy of a utopia that failed miserably on the last 20 civilizations they tired to “fix”. Sort of Clark’s 2001 aliens, but ultimately advanced incompetent fools.
As Arthur C. Clarke also has pointed out, any truly malignant, malevolent and violent civilization would have extinguished itself from existence long, long before it gets to us.
Islam is still around and causing trouble.
Beware the “Star Trek” Fallacy. If we encounter aliens, it is unlikely their technology level will anywhere close to ours.
Given the age if the universe, Monte Carlo simulations show that any intelligent species we encounter is likely to be millions of years ahead of us, or millions of years behind. Australopithecines or demi-gods, not Vulcans or Klingons.
Two hundred years ago, we couldn’t even detect radio waves, much less understand radio transmissions. Why assume that we would be able to detect/recognize a technology that’s one million years in advance of ours? (On the other hand, one their children might be watching our every move with his toy telescope.)
Maybe. If it survives long enough, any civilization will know 99% of everything knowable about physics and engineering. After that, a few million years may not make much difference in their technology.
It may be useful to consider the concept of an apex civilization, one that knows everything knowable about physics and engineering, or nearly so. What can they do?
It may be that they hit the wall of finite scientific knowledge a mere three orders of magnitude beyond us. A light year to them is like an A.U. to us, , and for a lightweight robotic flyby mission they can achieve a staggering .1 c.
That would be pretty impressive compared to us, but a pretty good explanation for our lack of visitors.
Why assume that we would be able to detect/recognize a technology that’s one million years in advance of ours?
If an expansionist alien race is that far ahead of us, we should be able to see their engineering from here. Their resource usage would almost inevitably lead to them rebuilding solar systems in a manner that should be obvious to us… for example, an entire arm of the galaxy going dark because they’ve built Dyson Spheres around the stars.
So I think it’s pretty clear that, if there are million-year-old technological alien races out there, they’re too busy looking inward, playing their equivalent of Call of Duty and posting on their equivalent of Facebook, to be looking for us.
Yeah, you can play the ‘but, but’ game, but the more convoluted explanations you toss out for why they might not want to make use of all available resources, the less likely the scenario becomes.
Dyson Spheres don’t work. They are unstable.
A solid sphere around a star is unstable. A swarm of satellites in interlacing orbits to collect a “large” portion of a star’s light works.
It works for a while, but the orbits will interact. Would they fly the many required to dim the star to observers? Would they grow the population without bounds so they require that much energy from any given star. Perhaps it’s better to just make new stars?
I’ve long pondered over old I Love Lucy broadcasts causing interstellar conflict. ;^)
Competent berserkers, or hostile alien civilizations generally, will not be hanging out fifty light-years away waiting for potential enemies to sent them a message by radio. They will have put stealthed satellites in orbit around every potentially life-bearing world within reach, a million years before anything with a synapse crawls out of the ocean, and implement the Ripley-Hicks doctrine no later than the first sighting of a campfire under the night sky.
Less wasteful alien civilizations will simply settle the place, at least with a cadre of scientists to observe and if necessary direct the evolution of any local intelligences.
The bit where we refrain from active SETI on account of not wanting to reveal ourselves to potential enemies, that’s us imagining we are up against an army of Daleks commanded by Inspector Clouseau. In which case, I’m with AndrewZ: commence with the taunting!
Absolutely. The Brin hypothesis requires the Terminators to be ancient, completely assiduous and utterly ruthless, and at the same time hopelessly incompetent.
The most parsimonious explanation is that planets are common, life may well be common, but intelligent life is very, very rare. You know what, I’m OK with that, because it means that the Universe is ours for the taking.
Pass me the 20mm Gauss Rifle, the hunting season for Arcturian Megalizards is about to start 😉
Results from WISE imply that at most 1 in 100,000 galaxies hosts a Kardashev Type III civilization.
IMO, the most likely explanation of the Fermi paradox is that intelligent life is extremely rare, and we have nothing to worry about transmitting out into the empty void.
Does that study indicate an upper limit for type II civilizations?
Scientists?
There’s no point in doing any science when one can instead listen in on the knowledge of others who since millions of years have already discovered everything which is possible to know.
Botanic and zoological taxonomy are sciences. Animal husbandry and genetic engineering are applied sciences. If there’s life on Earth that hasn’t evolved scientists and no other alien civilization has sent its scientists to Earth, then there’s science to be done on Earth.
The existence of a supercivilization on a galactic Dyson sphere in the Virgo cluster that knows literally everything that is theoretically knowable from a Dyson sphere in the Virgo cluster, doesn’t change that, because there are things that are absolutely unknowable from that vantage point. Wicked cool things, like the fact that cavemen not only coexisted with dinosaurs but may have trained them to hunt other dinosaurs. These things, you just plain have to go to Earth to study.
That not one alien scientist could pry his bulbous green nose away from measuring the forty-second decimal place of the mass of the Higgs Boson to investigate the sheer awesomeness of a dinosaur/caveman aerial alliance, or stick around to tell us about it, I take as nearly proof that aliens either don’t exist or have such universally poor taste that we might as well ignore them anyway.
Or a hostile alien civilization might just send a person to become President of the United States who promises nothing other than Hope and Change, and destroys the country with a series of multi-billion dollar heists unopposed by Congress, the Judiciary, or the press.
No, wait. That could never happen. Chris Matthews would never rest until he saw a birth certificate…
This is handwringing and drama over a question about which we have no information. We might as well speculate on the afterlife: We *don’t know* at this point.
A few decades ago, people were writing about the rare Earth hypothesis, and how our planet was so exceedingly unlikely, there would only be one of them like it in the observable universe. Adherents speculated that star systems with planets were rare. When we began discovering gas giants, people were wringing their hands about there being no terrestrial planets in the sky (even though we couldn’t see them.) Now, with Kepler, we know that planets are actually pretty common, terrestrials are common – not only that, but many star systems don’t necessarily have to look anything like the solar system. And we’ve found hundreds of candidates for terrestrial planets in a habitable zone (which still doesn’t tell us they are Earthlike, but it is pretty strong evidence against ‘rare Earth’ hypotheses).
Now that we know, the picture has changed dramatically.
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About power requirements for interstellar communication: Basic back of the envelope calculations lead me to believe that any interstellar communications must necessarily be highly directional. That means, you have to know what to point your signal at before you broadcast, if you want anyone to have any hope of picking it up. A 1 GW omnidirectional transmission will have 1E-32 W/m^2 of power by the time it reaches Alpha Centauri. SETI scenarios seem to assume that alien civilizations would have extremely large aperture (kms) high gain antennae pointed directly at us – and they would have to to pick anything up even at that small distance.
You can crank this up to 1E-17 W/m^2 (leading to a 1E-12 W/m^2 signal in a km wide dish pointed directly at us) if you had a 0.1 mrad half-angle high gain antennae to broadcast your GW signal with. It would also make a nice microwave death-ray near to the source of the broadcaster.
Just because you can draw a circle on a map that we’ve theoretically effected the EM spectrum at, doesn’t mean that anyone can detect us at that range.
1E-12 W, not W/m^2 for the signal power at the receiver.
I also like to bring up the Gallileo probe with its damaged high-gain antenna: It took the aperture of the entire deep space network acting in concert with supercooled detectors to pick its omnidirectional antenna signal out of the background noise and extract 1 bit per minute from it at Jupiter. We could only find it again because *we knew exactly where to look*. We could never have detected something like the Gallileo probe at that distance if it were something like an alien probe or a million-times more powerful signal from a more distant star.
A nitpick: If you read Rare Earth, you’ll see that authors Peter Ward and Donald Brownlee argue that life on other planets will be quite common, it is merely complex life (multicellular life, or some alien equivalent) which will be rare.
This doesn’t take away from your point, but it bugs me when people attribute an argument to Rare Earth which is nearly the opposite of the argument the authors actually lay out.
Using an omni antenna for interstellar transmissions is insane, all you’re doing is warming up the microwave background. The covering factor of stellar systems within communication range is very small.
A sufficiently advanced civilisation would use stellar gravitational foci for targeted searches and communications: http://www.centauri-dreams.org/?p=785 …and they’d already know with high confidence where all the nearby life-bearing systems were.
PS – the calls for global government to shut people up for the sake of the precautionary principle, and calls for collective suppression of individual initiative just warms the heart, doesn’t it? It brings to mind the impulse to control people to appease angry deities in ages past.
Yes. it was surprising to see that at Cato.
Just a note about our inadvertent transmissions.
It’s nice to imagine that Denver Colorado’s Channel 2 has been transmitting in the blind to Space Aliens for over sixty years. However, just how many “Channel 2s” are there in the United States alone? That frequency alone should have been a holy hell of hodgepodged hash by the time it left the Asteroid Belt.
That’s what we get for setting transmission standards.
To all of the conditions required for a civilization to exist and be spacefaring (a planet in the habitable zone, complete with water and an atmosphere, etc.), I would add another that I’ve never heard mentioned, viz the planet can’t be any more than 5 times as massive as the earth. At approximately that mass, it would be impossible to place an object into orbit with chemical rockets. And I doubt if any civilization would ever bother with space if that first hurdle couldn’t be crossed.
The Drake Equation is generally used to think about how to estimate the number of communicating civilizations out there. If we add the planetary mass criterion as a factor, it would allow us to estimate the number of civilizations that could in principle be spacefaring. On top of that, one would have to put a factor on the probability of them actually becoming spacefaring, and finally another on the probability that interstellar travel is even possible (I’ve been in the space launch world for most of my 34 year career, and I am not convinced it is possible).
So what is the risk of us getting invaded? The Drake Equation estimates range from 2 to 128 million civilizations in our galaxy. If we put the spacefaring factors on the high estimate, it will surely knock this down. Let’s say there are really 1,000,000 spacefaring civilizations, and they are evenly distributed. The stellar density in the vicinity of earth is about 1 per 330 cubic light years. So the nearest communicating civilization would be on the order of 189 light-years away. None of us will be alive by the time they first hear us, nor is it likely that my children will still be around at that time. Assuming that first civilization has instant interstellar travel, they would at worst be a threat to our childrens’ children. And while I believe we should protect our children, I don’t believe we should protect our childrens’ children, because I don’t think children should be having sex in the first place.
You were doing so well there, MfK. Right up until the end.
And that’s when I knocked it clean out of the park!
See you next Monday. 🙂
Some common mistakes are made in the article.
1) We won’t have a relation with them. We will be nature to each other. Are for example humans and ants “friendly” to each other?
2) They will be everywhere, why wouldn’t they? The dinosaurs lived on the other side of the Milky Way, the Sun is our spaceship. If one travels only to the nearest stars, then in 0.25 billion years or so (2% of the age of the galaxy), one has colonized the entire galaxy. Why would no one anywhere ever have done that?
3) We don’t know if it is silent out there, we haven’t even had a look yet.
Imagine what it would be like if we could tune in the radio transmission from all over the galaxy! Some guys are million years older than others. It’d be like listening to Farao, Napoleon and Darth Vader all at once. Absurd. But they must be diverse, the speed of light makes coordination impossible on a galactic scale. A 10,000 year old message will not be treated as an order, but as a historical curiosity for a museum. And since they must be diverse, we must assume that everything has been tried by someone somewhere sometime.
ShOut the hell up, I say.
Let’s see if they can hear us scream in space after all. There’s nowhere to hide anyway.
This whole debate is an exercise in expressing one’s unshakeable belief that alien civilisations exist, which we have no evidence to support. The METI debate in particular requires a belief in malevolent aliens who have interstellar space travel, so that they can come here and do nasty things to us, but who at the same time do not have interstellar space travel, so that they were not already here billions of years ago. For them to be nearby but not yet to have reached the Solar System requires a very low probability coincidence.
We shouldn’t think of deliberately yelling before we can do it from relay station 10 light-years out, that is programmed to vaporize itself if Berserkers show up.
Here’s a very narrow criticism: There are only 9 known stellar systems within 10 light years of Earth, and three of those are unlikely sources of intelligent life (Sirius and two recently found brown dwarf systems). I believe that distribution is typical for our part of the galaxy, and if so, ten light years out for a relay station won’t do much to disguise our true location – the sun will stand out as a likely nearby candidate.
A more broad criticism: none of these considerations matter because we’re detectable via telescope from thousands of light years away. Google “FOCAL” and “Maccone” and optionally “centauri-dreams” to read about one such approach.
It’s a little late for that. Our first radio signals are now over 100 light years out and the first TV broadcast signals are nearly 80 light years out, and both still spreading at the speed of light.
A considerable number of those TV and radio broadcasts are stories about Earth defeating alien invaders who have vastly superior technology and the element of surprise. We’re not just shouting, we’re shouting “come and have a go if you think you’re hard enough!”
And pretty hard to detect at that distance. The SETI institute thinks that we’d unable detect ordinary radio and television from the closest star, and even with superior technology they’d be drowned out by background noise at some distance.
Brin is much more worried about a deliberate Yoohoo from a big radar dish,, or a lucky intercept of us using a big radar to look at, for example, an asteroid.
4. If aliens are near enough for us to get a response within centuries, then there are at least thousands of them out there that could yell or otherwise make themselves visible. But all of them instead seem to keep quiet and hide. That seems worrisome.
This strikes me as a learned behavior. How might it come about?
As pointed out, we’ve been shouting so that cats out of the bag. But a response from aggressive aliens would take time during which me might have colonies perhaps to near stars. Those other aliens that are silent would either have seen their home world wiped out or… didn’t survive to see it. Either way, silence.
If anyone has done an estimate of the RF power radiated by earth vs astronomical distances e.g 100+ light years – while taking into account space plasma distortions and the S/N relationship for galactic RF noise sources and quantum detectibility limits, please publish it here. I’m too frikken lazy to do it myself.
Thanx!
I haven’t done the math either, but a rough approximation in human terms is listening for someone whistling at an AC/DC concert. The music is loud, the crowd is loud, but you can still hear a whistle: a high intensity burst at a different frequency than the background. More detailed communication, say listening to someone talking two rows back, is far more difficult.
Right, basically integrating out the white noise while the tight bandwidth signal builds over time into something detectable. OTOH, if there are random walk noise processes – say varying large phase shifts and multipath due to parsecs of variously magnetized plasma, then the signal will get “smeared out” somewhat. So I guess the problem is how far out do you have to go and how much junk gets in the way such that the integration time is large in relation to the life span of an extra terrestrial SETI program? No doubt there’s a book someplace.
I’m appalled!
This “shut up” idea is disgustingly culturally insensitive, and thus shouldn’t be discussed, let alone suggested or implemented!
After all, we must value multiculturalism, and doing so means that we must, inherently, regard all cultures as equal – and with equal prerogatives. Thus, if there is an xenophobic genocidal alien culture out there that would exterminate us, that’s not wrong, it’s just part of their culture… and who are we to hinder them (via hiding) from freely practicing their culture wherever they see fit?
You left out the part about us polluting the galaxy’s precious electromagnetic waves with our signals.
After all, we’re just a planet of old white men and deserve to be destroyed before we contaminate the solar system with life that isn’t organically grown…
…Oh …that’s why colonization will cost 100’s of billions!.
It really is the ultimate hubris to think any truly advanced alien civilization would be interested in us. To what possible advantage (to them) would that be? Arthur C. Clarke compares SETI to like talking with your dog. You can do it, but it’s a pretty one sided conversation and you don’t keep it up for very long. Nor am I worried about marauding, malevolent, not so advanced aliens. The universe is very very old. As Arthur C. Clarke also has pointed out, any truly malignant, malevolent and violent civilization would have extinguished itself from existence long, long before it gets to us. Nuclear proliferation is just one very very small example of this principle. Now if that civilization were on the next planet, that might be a different story! Looks like we lucked out!
They may not be interested in us, but knowing we exist may point them in the direction of a nice fixer upper water planet.
We might extinguish ourselves, but with starflight they may only extinguish a home world here and there making earth even more valuable (supply and demand.)
Why would they find Earth attractive? We can only live here and now, or in a colony which we create. A few hundred million years ago we couldn’t survive on Earth because there wouldn’t be enough oxygen in the atmosphere and maybe nothing here which we could eat. And actually, we are co-evolving together with our microbes on even shorter timescales.
Why would they find Earth attractive?
Are you not from here?
“As Arthur C. Clarke also has pointed out, any truly malignant, malevolent and violent civilization would have extinguished itself from existence long, long before it gets to us.”
One hopes…
As Arthur C. Clarke also has pointed out, any truly malignant, malevolent and violent civilization would have extinguished itself from existence long, long before it gets to us.
Written during the height of MAD of course, just as “War of the Worlds” reflected the imperialist state of the world at the time by one of Clark’s predecessors. What “advanced” civilizations will actually be like is as unknowable as the scientific landscape of X years in the future. Following Well’s and Clark’s example though, I’d hypothesize a race of busybody nihilists looking to transform this planet’s inhabitants into beings worthy of a utopia that failed miserably on the last 20 civilizations they tired to “fix”. Sort of Clark’s 2001 aliens, but ultimately advanced incompetent fools.
As Arthur C. Clarke also has pointed out, any truly malignant, malevolent and violent civilization would have extinguished itself from existence long, long before it gets to us.
Islam is still around and causing trouble.
Beware the “Star Trek” Fallacy. If we encounter aliens, it is unlikely their technology level will anywhere close to ours.
Given the age if the universe, Monte Carlo simulations show that any intelligent species we encounter is likely to be millions of years ahead of us, or millions of years behind. Australopithecines or demi-gods, not Vulcans or Klingons.
Two hundred years ago, we couldn’t even detect radio waves, much less understand radio transmissions. Why assume that we would be able to detect/recognize a technology that’s one million years in advance of ours? (On the other hand, one their children might be watching our every move with his toy telescope.)
Maybe. If it survives long enough, any civilization will know 99% of everything knowable about physics and engineering. After that, a few million years may not make much difference in their technology.
It may be useful to consider the concept of an apex civilization, one that knows everything knowable about physics and engineering, or nearly so. What can they do?
It may be that they hit the wall of finite scientific knowledge a mere three orders of magnitude beyond us. A light year to them is like an A.U. to us, , and for a lightweight robotic flyby mission they can achieve a staggering .1 c.
That would be pretty impressive compared to us, but a pretty good explanation for our lack of visitors.
Why assume that we would be able to detect/recognize a technology that’s one million years in advance of ours?
If an expansionist alien race is that far ahead of us, we should be able to see their engineering from here. Their resource usage would almost inevitably lead to them rebuilding solar systems in a manner that should be obvious to us… for example, an entire arm of the galaxy going dark because they’ve built Dyson Spheres around the stars.
So I think it’s pretty clear that, if there are million-year-old technological alien races out there, they’re too busy looking inward, playing their equivalent of Call of Duty and posting on their equivalent of Facebook, to be looking for us.
Yeah, you can play the ‘but, but’ game, but the more convoluted explanations you toss out for why they might not want to make use of all available resources, the less likely the scenario becomes.
Dyson Spheres don’t work. They are unstable.
A solid sphere around a star is unstable. A swarm of satellites in interlacing orbits to collect a “large” portion of a star’s light works.
It works for a while, but the orbits will interact. Would they fly the many required to dim the star to observers? Would they grow the population without bounds so they require that much energy from any given star. Perhaps it’s better to just make new stars?
My thoughts exactly…
http://xkcd.com/1377/
I’ve long pondered over old I Love Lucy broadcasts causing interstellar conflict. ;^)
Competent berserkers, or hostile alien civilizations generally, will not be hanging out fifty light-years away waiting for potential enemies to sent them a message by radio. They will have put stealthed satellites in orbit around every potentially life-bearing world within reach, a million years before anything with a synapse crawls out of the ocean, and implement the Ripley-Hicks doctrine no later than the first sighting of a campfire under the night sky.
Less wasteful alien civilizations will simply settle the place, at least with a cadre of scientists to observe and if necessary direct the evolution of any local intelligences.
The bit where we refrain from active SETI on account of not wanting to reveal ourselves to potential enemies, that’s us imagining we are up against an army of Daleks commanded by Inspector Clouseau. In which case, I’m with AndrewZ: commence with the taunting!
Absolutely. The Brin hypothesis requires the Terminators to be ancient, completely assiduous and utterly ruthless, and at the same time hopelessly incompetent.
The most parsimonious explanation is that planets are common, life may well be common, but intelligent life is very, very rare. You know what, I’m OK with that, because it means that the Universe is ours for the taking.
Pass me the 20mm Gauss Rifle, the hunting season for Arcturian Megalizards is about to start 😉
Results from WISE imply that at most 1 in 100,000 galaxies hosts a Kardashev Type III civilization.
IMO, the most likely explanation of the Fermi paradox is that intelligent life is extremely rare, and we have nothing to worry about transmitting out into the empty void.
Does that study indicate an upper limit for type II civilizations?
Scientists?
There’s no point in doing any science when one can instead listen in on the knowledge of others who since millions of years have already discovered everything which is possible to know.
Botanic and zoological taxonomy are sciences. Animal husbandry and genetic engineering are applied sciences. If there’s life on Earth that hasn’t evolved scientists and no other alien civilization has sent its scientists to Earth, then there’s science to be done on Earth.
The existence of a supercivilization on a galactic Dyson sphere in the Virgo cluster that knows literally everything that is theoretically knowable from a Dyson sphere in the Virgo cluster, doesn’t change that, because there are things that are absolutely unknowable from that vantage point. Wicked cool things, like the fact that cavemen not only coexisted with dinosaurs but may have trained them to hunt other dinosaurs. These things, you just plain have to go to Earth to study.
That not one alien scientist could pry his bulbous green nose away from measuring the forty-second decimal place of the mass of the Higgs Boson to investigate the sheer awesomeness of a dinosaur/caveman aerial alliance, or stick around to tell us about it, I take as nearly proof that aliens either don’t exist or have such universally poor taste that we might as well ignore them anyway.
Or a hostile alien civilization might just send a person to become President of the United States who promises nothing other than Hope and Change, and destroys the country with a series of multi-billion dollar heists unopposed by Congress, the Judiciary, or the press.
No, wait. That could never happen. Chris Matthews would never rest until he saw a birth certificate…
This is handwringing and drama over a question about which we have no information. We might as well speculate on the afterlife: We *don’t know* at this point.
A few decades ago, people were writing about the rare Earth hypothesis, and how our planet was so exceedingly unlikely, there would only be one of them like it in the observable universe. Adherents speculated that star systems with planets were rare. When we began discovering gas giants, people were wringing their hands about there being no terrestrial planets in the sky (even though we couldn’t see them.) Now, with Kepler, we know that planets are actually pretty common, terrestrials are common – not only that, but many star systems don’t necessarily have to look anything like the solar system. And we’ve found hundreds of candidates for terrestrial planets in a habitable zone (which still doesn’t tell us they are Earthlike, but it is pretty strong evidence against ‘rare Earth’ hypotheses).
Now that we know, the picture has changed dramatically.
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About power requirements for interstellar communication: Basic back of the envelope calculations lead me to believe that any interstellar communications must necessarily be highly directional. That means, you have to know what to point your signal at before you broadcast, if you want anyone to have any hope of picking it up. A 1 GW omnidirectional transmission will have 1E-32 W/m^2 of power by the time it reaches Alpha Centauri. SETI scenarios seem to assume that alien civilizations would have extremely large aperture (kms) high gain antennae pointed directly at us – and they would have to to pick anything up even at that small distance.
You can crank this up to 1E-17 W/m^2 (leading to a 1E-12 W/m^2 signal in a km wide dish pointed directly at us) if you had a 0.1 mrad half-angle high gain antennae to broadcast your GW signal with. It would also make a nice microwave death-ray near to the source of the broadcaster.
Just because you can draw a circle on a map that we’ve theoretically effected the EM spectrum at, doesn’t mean that anyone can detect us at that range.
1E-12 W, not W/m^2 for the signal power at the receiver.
I also like to bring up the Gallileo probe with its damaged high-gain antenna: It took the aperture of the entire deep space network acting in concert with supercooled detectors to pick its omnidirectional antenna signal out of the background noise and extract 1 bit per minute from it at Jupiter. We could only find it again because *we knew exactly where to look*. We could never have detected something like the Gallileo probe at that distance if it were something like an alien probe or a million-times more powerful signal from a more distant star.
A nitpick: If you read Rare Earth, you’ll see that authors Peter Ward and Donald Brownlee argue that life on other planets will be quite common, it is merely complex life (multicellular life, or some alien equivalent) which will be rare.
This doesn’t take away from your point, but it bugs me when people attribute an argument to Rare Earth which is nearly the opposite of the argument the authors actually lay out.
Using an omni antenna for interstellar transmissions is insane, all you’re doing is warming up the microwave background. The covering factor of stellar systems within communication range is very small.
A sufficiently advanced civilisation would use stellar gravitational foci for targeted searches and communications: http://www.centauri-dreams.org/?p=785 …and they’d already know with high confidence where all the nearby life-bearing systems were.
PS – the calls for global government to shut people up for the sake of the precautionary principle, and calls for collective suppression of individual initiative just warms the heart, doesn’t it? It brings to mind the impulse to control people to appease angry deities in ages past.
Yes. it was surprising to see that at Cato.
Just a note about our inadvertent transmissions.
It’s nice to imagine that Denver Colorado’s Channel 2 has been transmitting in the blind to Space Aliens for over sixty years. However, just how many “Channel 2s” are there in the United States alone? That frequency alone should have been a holy hell of hodgepodged hash by the time it left the Asteroid Belt.
That’s what we get for setting transmission standards.
To all of the conditions required for a civilization to exist and be spacefaring (a planet in the habitable zone, complete with water and an atmosphere, etc.), I would add another that I’ve never heard mentioned, viz the planet can’t be any more than 5 times as massive as the earth. At approximately that mass, it would be impossible to place an object into orbit with chemical rockets. And I doubt if any civilization would ever bother with space if that first hurdle couldn’t be crossed.
The Drake Equation is generally used to think about how to estimate the number of communicating civilizations out there. If we add the planetary mass criterion as a factor, it would allow us to estimate the number of civilizations that could in principle be spacefaring. On top of that, one would have to put a factor on the probability of them actually becoming spacefaring, and finally another on the probability that interstellar travel is even possible (I’ve been in the space launch world for most of my 34 year career, and I am not convinced it is possible).
So what is the risk of us getting invaded? The Drake Equation estimates range from 2 to 128 million civilizations in our galaxy. If we put the spacefaring factors on the high estimate, it will surely knock this down. Let’s say there are really 1,000,000 spacefaring civilizations, and they are evenly distributed. The stellar density in the vicinity of earth is about 1 per 330 cubic light years. So the nearest communicating civilization would be on the order of 189 light-years away. None of us will be alive by the time they first hear us, nor is it likely that my children will still be around at that time. Assuming that first civilization has instant interstellar travel, they would at worst be a threat to our childrens’ children. And while I believe we should protect our children, I don’t believe we should protect our childrens’ children, because I don’t think children should be having sex in the first place.
You were doing so well there, MfK. Right up until the end.
And that’s when I knocked it clean out of the park!
See you next Monday. 🙂
Some common mistakes are made in the article.
1) We won’t have a relation with them. We will be nature to each other. Are for example humans and ants “friendly” to each other?
2) They will be everywhere, why wouldn’t they? The dinosaurs lived on the other side of the Milky Way, the Sun is our spaceship. If one travels only to the nearest stars, then in 0.25 billion years or so (2% of the age of the galaxy), one has colonized the entire galaxy. Why would no one anywhere ever have done that?
3) We don’t know if it is silent out there, we haven’t even had a look yet.
Imagine what it would be like if we could tune in the radio transmission from all over the galaxy! Some guys are million years older than others. It’d be like listening to Farao, Napoleon and Darth Vader all at once. Absurd. But they must be diverse, the speed of light makes coordination impossible on a galactic scale. A 10,000 year old message will not be treated as an order, but as a historical curiosity for a museum. And since they must be diverse, we must assume that everything has been tried by someone somewhere sometime.
ShOut the hell up, I say.
Let’s see if they can hear us scream in space after all. There’s nowhere to hide anyway.
This whole debate is an exercise in expressing one’s unshakeable belief that alien civilisations exist, which we have no evidence to support. The METI debate in particular requires a belief in malevolent aliens who have interstellar space travel, so that they can come here and do nasty things to us, but who at the same time do not have interstellar space travel, so that they were not already here billions of years ago. For them to be nearby but not yet to have reached the Solar System requires a very low probability coincidence.