Scientists Say Most Likely Number of Contactable Alien Civilizations Is 36 (theguardian.com) 181
An anonymous reader quotes a report from The Guardian: They may not be little green men. They may not arrive in a vast spaceship. But according to new calculations there could be more than 30 intelligent civilizations in our galaxy today capable of communicating with others. In 1961 the astronomer Frank Drake proposed what became known as the Drake equation, setting out seven factors that would need to be known to come up with an estimate for the number of intelligent civilizations out there. These factors ranged from the the average number of stars that form each year in the galaxy through to the timespan over which a civilization would be expected to be sending out detectable signals.
But few of the factors are measurable. "Drake equation estimates have ranged from zero to a few billion [civilizations] -- it is more like a tool for thinking about questions rather than something that has actually been solved," said Christopher Conselice, a professor of astrophysics at the University of Nottingham and a co-author of the research. Now Conselice and colleagues report in the Astrophysical Journal how they refined the equation with new data and assumptions to come up with their estimates. "Basically, we made the assumption that intelligent life would form on other [Earth-like] planets like it has on Earth, so within a few billion years life would automatically form as a natural part of evolution," said Conselice.
The assumption, known as the Astrobiological Copernican Principle, is fair as everything from chemical reactions to star formation is known to occur if the conditions are right, he said. "[If intelligent life forms] in a scientific way, not just a random way or just a very unique way, then you would expect at least this many civilizations within our galaxy," he said. Under the strictest set of assumptions -- where, as on Earth, life forms between 4.5 billion and 5.5 billion years after star formation -- there are likely between four and 211 civilizations in the Milky Way today capable of communicating with others, with 36 the most likely figure. But Conselice noted that this figure is conservative, not least as it is based on how long our own civilization has been sending out signals into space -- a period of just 100 years so far. The team add that our civilization would need to survive at least another 6,120 years for two-way communication. "They would be quite far away ... 17,000 light years is our calculation for the closest one," said Conselice. "If we do find things closer ... then that would be a good indication that the lifespan of [communicating] civilizations is much longer than a hundred or a few hundred years, that an intelligent civilization can last for thousands or millions of years. The more we find nearby, the better it looks for the long-term survival of our own civilization."
But few of the factors are measurable. "Drake equation estimates have ranged from zero to a few billion [civilizations] -- it is more like a tool for thinking about questions rather than something that has actually been solved," said Christopher Conselice, a professor of astrophysics at the University of Nottingham and a co-author of the research. Now Conselice and colleagues report in the Astrophysical Journal how they refined the equation with new data and assumptions to come up with their estimates. "Basically, we made the assumption that intelligent life would form on other [Earth-like] planets like it has on Earth, so within a few billion years life would automatically form as a natural part of evolution," said Conselice.
The assumption, known as the Astrobiological Copernican Principle, is fair as everything from chemical reactions to star formation is known to occur if the conditions are right, he said. "[If intelligent life forms] in a scientific way, not just a random way or just a very unique way, then you would expect at least this many civilizations within our galaxy," he said. Under the strictest set of assumptions -- where, as on Earth, life forms between 4.5 billion and 5.5 billion years after star formation -- there are likely between four and 211 civilizations in the Milky Way today capable of communicating with others, with 36 the most likely figure. But Conselice noted that this figure is conservative, not least as it is based on how long our own civilization has been sending out signals into space -- a period of just 100 years so far. The team add that our civilization would need to survive at least another 6,120 years for two-way communication. "They would be quite far away ... 17,000 light years is our calculation for the closest one," said Conselice. "If we do find things closer ... then that would be a good indication that the lifespan of [communicating] civilizations is much longer than a hundred or a few hundred years, that an intelligent civilization can last for thousands or millions of years. The more we find nearby, the better it looks for the long-term survival of our own civilization."
It's not 36 (Score:5, Funny)
They need to check their numbers again, I'm pretty sure the number of contactable alien civilizations is 42.
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The more we find nearby, the better it looks for the long-term survival of our own civilization.
Unless they eat us.
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I'd be more concerned that we go there and eat them.
We're far from being the innocent victim in interstellar warfare. We're only pictured as such because we can't yet become the evil aliens from all those movies, for technological reasons.
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I stand corrected.
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PETA = People Eating Tasty Aliens?
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"Unless they eat us."
I see you read Damon Knight's story 'To Serve Man".
https://en.wikipedia.org/wiki/... [wikipedia.org]
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nospam007 observed:
"Unless they eat us."
I see you read Damon Knight's story 'To Serve Man".
https://en.wikipedia.org/wiki/... [wikipedia.org]
Or he watched the iconic Twilight Zone episode of the same name. Or The Simpsons' Treehouse of Horror episodelet, also, unsurprisingly, of the same name ...
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Actually, the Simpson skit was titled "Hungry are the Damned"
Uncertainty (Score:5, Informative)
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Re:Uncertainty (Score:5, Insightful)
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I suspect the probability distribution will give a 1 sigma range of 0 to ~1e9.
And the left tail is probably chopped off at 0.
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It also depends how you define contactable. With hundreds of years delay for messages to travel, unknown communication methods (radio, light, gravity waves, something we don't even know about), and civilizations arriving at these stages at different times you can define it pretty loosely.
Re: It's not 36 (Score:2)
I came here to write this. It's all cool. :)
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Wrong (Score:2)
The number is obviously either zero or they are smart enough to stay the hell away from us other than maybe watch as some sort of dark comedy reality TV.
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Actually they planted a Tribble-headed chubby guy to stir things up as an experiment.
Right direction, Re:Wrong [destination] (Score:5, Interesting)
Okay, so they have improved on some of the Drake equation parameters, but there are still far too many unknowns to come up with a specific number. Unless the 36 is supposed to be a joke.
The actual answer is "One (other) would be enough". If there were one stable intelligent species with our level of technical (and pretending that homo sapiens is an intelligent species), then that species would have been found if it wanted to. All it would take is one radio beacon operated for 100,000 years and the entire Milky Way would be saturated with the signals.
That's the angle I took on the Fermi Paradox many years ago. Lots of possible resolutions of the paradox. My favorite resolution is based on naturally evolved intelligence not lasting long. It either exterminates itself or replaces itself with artificially designed synthetic intelligence.
On the self-extermination branch, I think a bio-weapon is the most likely method. A sufficiently nasty genetic engineering accident could do it, but I think suicidal behaviors are more likely. When CRISPR kits became cheap, the odds against the other branch went way down.
However, I still hope that some species have survived long enough to replace themselves. If so, the replacements must be benign and curious, or else they would have exterminated us long ago. My theory is that their own evolution converges, basically because the physical laws of the universe are consistent, but they migh still be curious about the random paths of evolution along the way. Maybe even gambling quatloos on us? (Or they could be indifferent to us for the same reason we don't pay a lot of attention to ants.)
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I was referring to convergent evolution of the AIs. The basic difference is that intelligent designers (that actually exist) are not blind, whereas Darwinian evolution is fundamentally a random process. The genes themselves are not sentient nor capable of perception. There are too many places where blind and random evolution can make arbitrary decisions, and the convergent part happens at a higher level, as when various species in different places develop similar forms because they are exploiting similar ec
Re:Right direction, Re:Wrong [destination] (Score:5, Insightful)
Or you know, detecting civilizations on other planets is really hard and we are amateurs at it. We've only started detecting planets in other solar systems in the last 20 or so years with an regularity. And the vast majority are gas giants. The few rocky ones are usually too large, or tidally locked to red dwarfs or other BS that allowed them to be detected with our primitive technology in the first place. We haven't found an Earth analog yet. And I suspect that has more to do with us being bad at this than it does a planet in our size category orbiting a star similar to our own being a particularly rare thing.
Also I'm not so sure that an active galactic community means busy RF bands. We don't broadcast all that much out into deep space. We did at first when powerful transmitters were omnidirectoinal. But today most transmissions going into space are microwave links to communications satellites. They are very directional and "clean" as far as EMI generation goes. Why are people assuming that other potential intelligent races would be any different? To create the kind of omnidirectional, indiscriminate transmissions necessary for us to detect and they not be intentionally sent to us would likely mean their communications industry is hopelessly inefficient and dysfunctional. We have occasionally sent intentional high powered transmissions to stellar objects but to detect them someone would have had to been there, at the right time, with the right equipment looking in our direction to pick it up. And that's not to mention the good odds that our transmissions were shifting into garbage after a few light years anyways.
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South Park already did it [wikipedia.org].
The joke above is another South Park reference [wikipedia.org], for those who didn't get it.
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To hate us, would be to hate themselves as this stage of their social evolution. The emotional attachment to us would be powerful, the chance to relive what their ancestor went through and yet entirely different.
The problem is for intelligence, it is a tricker evolutionary thing. The evolutionary environment has to promote intellectual development over physical. Physical is evolution is slower than mental social evolution but the physical evolution to allow that must occur first and it must have an advanta
Drake equation is missing a few terms (Score:3, Interesting)
The number is obviously either zero or they are smart enough to stay the hell away from us other than maybe watch as some sort of dark comedy reality TV.
I believe the Drake is also missing a few terms.
Our own system has a moon capable of making tides. Moons are quite common (there are several examples in our solar system), but ones large enough to make tides are seemingly rare.
A system with tides allows developing life to anchor in place and filter the water in tidal pools as it sloshes back and forth, speeding up the rate of evolution.
Also, our moon was formed by a collision early on in Earth's history, which gave us a large molten core on which the contin
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Additionally, without some form of easily mined energy (coal, oil) any civilization would be unable to progress beyond the iron age.
I wonder if that's true. Certainly there was a lot of wind power and water power driving industrial processes in the 1800s (and even before). What would we have done if we could never have gotten cheap coal or oil?
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The romans had water powered manufactories. Usually about 4 - 6, sometimes 8 water wheels in a row.
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We might really be the 1st intelligent civilization in our galaxy, which would explain the Fermi paradox.
And we may well be the first to die out of our own stupidity. The Drake equation also doesn't take into account the chance for a civilisation to act in their collective best interests. Honestly it's quite a feat that we managed to live through our period of tribalism, two world wars, and didn't nuke the entire planet into glass.
To say nothing of the fact that Yellowstone could just end us all at any moment. The Drake equation was also missing the fts term where a planet suddenly says fuck this shit and purg
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The Drake equation doesn't account for having a large moon.
That falls under Fi
"the fraction of planets that could support life that actually develop life at some point"
The Drake equation has no term for whether any world has a ready-made supply of energy (coal or oil) to help it get into the industrial age.
That falls under Fc * L
"the fraction of civilizations that develop a technology that releases detectable signs of their existence into space"
and
"the length of time for which such civilizations release detectable signals into space"
We might really be the 1st intelligent civilization in our galaxy, which would explain the Fermi paradox.
Although you are incorrect about the equation not having terms for the things you list, I would completely agree those may often not be factored in, and when they are, prob
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> Even up to three total could easily end up beyond the possibility of detecting, if there is an even spacial distribution and the galactic core is in the way.
I don't understand. Did they estimate 36 contemporaneous (relative to our place) civilizations, ie. if all of them emitted radio toward us some time ago, we could listen to all of them? Or 36 civilizations ever, so far? Because there could've been millions of brief, 1000-year old technological civilizations over the 4.5bn years and we still wouldn'
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These are all good points, I'd be very surprised if the existence of the Moon wasn't taken into account for modeling, as the effect of tide is one of the first things I heard as a kid, as something that helped evolution. I think scientists are smarter than I was as a kid.
Increasing the number of criteria will increase our confidence in whatever galaxy-wide count estimate we come up with. But equally, they lower the count, as it's hard enough to make out faraway planets, let alone their moons.
Also, there may
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> We might really be the 1st intelligent civilization in our galaxy, which would explain the Fermi paradox.
We're not. Your wishful thinking, false ego, and pride is talking.
Humans are only slightly above average intelligence compared to all the other intelligent life in the universe.
* We can take (some) comfort knowing that we aren't the dumbest species around.
* And we can have humility knowing that we aren't the smartest.
What makes humans unique is our ability for Compassion or TLC (Tender Loving Care.)
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I suspect the missing term is for multicellular life. Life on earth appeared pretty quickly, possibly within 100s of million years of the oceans forming.
Then theres a 3 billion year wait for multicellular life, and from there we get nervous systems and brains pretty quickly.
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Any galactic civilization will probably classify us in the cabinet labeled 'short-lived' . The cabinet is too large to make it embarassing. It's one of those industrial dark grey ones with a dull worn look and a lot of scratches but the paint does not peel off so that is nice.
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given that an intelligent civilization would probably not destroy the only place in the universe where they know for sure that they can live
This always comes up. It's basically a way to cram environmental talking points into a conversation where it isn't required.
It's also silly. Did you have a better plan to get from upright monkeys to landing on the Moon? I mean other than the path we took through the industrial revolution, western civilization, etc. that apparently has brought us to the brink of extinction at least a half dozen times that I can recall in my lifetime.
The number of alien civilizations is 0 according to the best data we have. T
To serve mankind (Score:2)
Yes, they just made contact with the Pullfiguresouttayourasssians.
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The correct title is To Serve Man [wikipedia.org], not mankind.
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I thought it was How To Cook Humans [youtu.be], although maybe my memory is a little dusty.
Re:To serve mankind (Score:4, Insightful)
The Drake equation is close to useless. Take a lot of wildly unknown variables, multiple them together, and that somehow gets you a number. If even one term is wrong or missing the probable number of planets with life can easily be below one.
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And yet, if TWO terms are wrong the answer is righ (Score:2)
That's true.
Also, if you choose at random five numbers from the range 1-10 and multiply them together, you're very likely to get an answer close to 5,000. Adding the numbers will give a very different answer, probably close to 27.5.
Enrico Fermi was a famous Nobel prize winning physicist who used this idea extensively. As it happens, if you have a 10X degree of uncertainty in several variables, you're reasonably likely to guesstimate some much too low and some much too high, yielding a reasonably good ans
I see words, I see careful euphemisms... (Score:2)
[If intelligent life forms] in a scientific way, not just a random way or just a very unique way
...but what does this actually even mean?
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[If intelligent life forms] in a scientific way, not just a random way or just a very unique way
...but what does this actually even mean?
It means that once trustworthy names in news are now nothing more than tabloid tier garbage.
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Such faith in a nonsense sentence, as long as it's "sciencey".
Don't worry about my team, worry about yours, as its eliminated down to the last hominid.
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Side note: "It causally happened by means of causality happens", the clearer paraphrased equivalent, says absolutely nothing.
Hmm... (Score:4, Funny)
more Drake Equation garbage. (Score:5, Insightful)
This equation was never meant to 'conclude' anything. It is the ultimate in garbage in garbage out. Yes, some numbers can be known (especially now that we have a better idea the number of planets around the stars on average), but so many other parameters are just made up. These idiots can make all the excuses they want for why they picked their numbers, but it is still a guess with no evidence for it at all.
The popular press articles on this are just pissing me off at how credulous they are, and it just gives *real* science a bad name when this pseudo-crap is given the name "science". There's no science here at all - no experiments, no controls, no PROOF. Just different numbers than the last guys who got famous for 15 minutes with their version of the same.
Drake never intended his equation to be used like this.
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Is the will of the guy who discovered the equation relevant on how it should be used?
Does the fact that we cannot know precisely certain terms imply that it is pointless to compute lower and upper bounds or most probable values?
Is making hypotheses in order to get numerical values that could be contradicted by observation completely stupid? (e.g., if the most probable distance for the closest civ had been 5ly, could we not deduce something about the hypotheses that led to this result?)
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"Our hypothesis that we're publishing to the masses is that if we put these values in, we get 36.
"Where did you get those values?"
"Uh, we made them up."
"Can you prove in any way that the the numbers might be right?"
"Uh...no."
"Is there even an experiment you can propose that might prove one of those numbers to be right?"
"Uh...no."
That's not science. It is speculation hiding behind numbers, which is exactly the same crap we condemn creationism to the scrap-heap for.
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Very much this. Science is a hypothesis (guess) + experiments to try to disprove it. Like a lot of what passes for science these days this is just the first half. Still, I suppose science can be twisted and corrupted just like anything else.
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Indeed. One set of the values in the equation was the average number of planets, and average number of planets in the 'earth-like' range ideal for liquid water (granted, the presumption that life must be water based is kinda built into the it, so there's already a bias on what defines 'life' ;-) ).
Those numbers we now have, thanks to all of the extra-solar planetary discoveries in the last decade. This is how it should work: what can we do to turn one of those numbers from a made up one to a range with vali
Noise like radio signals (Score:5, Interesting)
We are rapidly sun-setting the "detectable signal" era already. While we still transmit lots of radio signals we have moved from signals that had a clearly defined pilot signal (AM, FM, VSB+C, etc) to digital broadcasting that has largely scrambled/eliminated the carrier tone to a very low level. Cell phone communication us ubiquitous, yet is designed to both be low power and noise like in appearance. Each phone transmits only up to a couple tenths of a watt, and that power is spread over MHz of bandwidth with psuedo-random encoding.
Basically this reduces the radius of stars from which Earth's signals can be picked up from greatly. As time marches on the remaining AM and FM broadcasting channels will either fade away in favor of internet based broadcast, digital broadcasting, or podcasts. It is worth realizing that Voyager, just beyond the limits of our solar system, takes Y'uge antennas to communicate to using a very limited data bandwidth with both ends of the channel pointing their antennas right at eachother. Detecting unintentional signals across light-years once a civilization mostly optimizes their communications to near Shannon's limit gets far fetched very rapidly.
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There are plenty of other RF signals to detect other than cellular. Radar pulses of all kinds are periodic and in many cases high power.
Re:Noise like radio signals (Score:4, Interesting)
Re: Noise like radio signals (Score:3)
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Most signals are now encrypted, and directional, and/or low power we are not using high power broadcasts as much now
If this trend is normal then we could expect aliens civilisations communications to mostly never reach us, and if they do be white noise
Scientists pull a number out of their ass, (Score:2)
rinse it off and try to feed it to us. LOL!
Who set the number of players to 36? (Score:2)
Well, at least we know the number of other players on our galactic map. Whoever set this game up really loves those absurdly long epic games.
What is this "most likely" BS? (Score:2)
We actually have absolutely no friggen idea just how common intelligent life actually is. You can't extrapolate from a sample-size of 1.
And unfortunately, we can never know just how common it actually is until we can confirm at least one other data point.
All we know about the possibility for intelligent life in the universe is that it is provably some non-zero value, but that does not imply that it is likely, or even necessarily non-unique at any given moment in time.
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Maybe you can't, but politicians do that kind of thing every day.
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The primary sin of the Greeks was not sodomy but extrapolation.
Politicians (and everyone else) suck at extrapolating. Don't try it at home, kids.
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Obtuse enough.
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"Contactable"? Who wrote the title? Did they RTFA? (Score:5, Insightful)
"They would be quite far away ... 17,000 light years is our calculation for the closest one,"
Contactable if you are prepared to wait 34,000 years for a reply, right?
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Contactable if you are prepared to wait 34,000 years for a reply, right?
That's assuming any message we send now will get to them before they see our leader of the free world's Twitter feed, read the words #covfefe and conclude there's no intelligent life worth replying to on this world.
We ARE The Escape Pod. (Score:2)
We are all by ourselves now. The escape pod was consumed long ago and all record of our beginnings were lost when our home planet was destroyed.
These guys just want some grant money.
Slime or Robots (Score:2)
For billions of years, Earth was covered in Slime. Miraculously, the slime was not totally destroyed by one of several possible cataclysmic events.
Then for a couple of centuries or so, people develop radio technology.
But we know that about 100 years after developing radio, life forms develop powerful computers.
How long before the computers replace the life forms? 200 years? 300 years? 400 years? Either way a blink of an eye in terms of the history of the galaxy.
So if there is anything out there, it is p
If they know about us, they'll stay silent. (Score:4, Funny)
Because, a bit of careful observation and they'll be like "These fuckers are CRAZY!"
Little known fact (Score:2)
The Drake Equation is not named eponymously. Frank Drake actually named it after the detective character from his favorite TV show, Perry Mason.
Not Science (Score:2)
This isn't science, it's based upon zero evidence of alien life. You want people to stop believing in science even more than the climate change deniers and anti-vaxers do now?...keep this shit up and call it science.
Extrapolating (Score:2)
Quit being stupid. (Score:2)
Low quality individuals (Score:2)
The drake equation was created as a launching point for debate - it was never intended as a serious predictive formula. But inevitably, the pedestrian plodders that make up our modern day scientific priest cast take it literally, and make another breathless pronouncement. On the plus side, at least THIS baseless assertion doesn't result in serious damage to our economies - so that's something.
Why... (Score:2)
...are people paid to "scientifically deduce" conclusions that are more or less the same as the shit freshmen talk about when they're drunk/high in their dorm rooms?
And with basically the same level of reliability of the results?
Probability of no alien civilizations? (Score:5, Informative)
Of course the number 36 should be taken with the world's largest grain of salt, but I am curious if they calculated the probability that there are no contactable alien civilizations. Or alternatively, what's the probability that there is at least one out there. That seems to me to be a much more relevant question than the "most probable" value in a distribution that ranges from 4-211 (is that 95%? 99% uncertainty? I'm sure it's described in the paper).
In my experience "most probable values" (I assume they mean mode) depends upon knowing the shape of the probability distribution pretty well, whereas probability of a value being less than a certain number is less model-dependent. The beauty of CDF's.
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I've read entire books on this exact subject and most of them conclude that life likely exists and is plentiful throughout the universe, but intelligent life is an exceptionally rare possibility.
When analyzing how our development on this planet went from organic compounds to single cells to multi-cellular and so on all the way up to human, including the speed-bumps known as mass extinction events, it's quite a long and perilous journey. Our planet's been through a lot, and all of those events may have had
A galaxy gets colonized in only 90 million years (Score:2)
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The population won't forever increase though, we're almost done with that, 2nd derivative proves it. Peak population will be in less than 80 years.
Reasonable assumptions? No, the crucial/important things of environment and enduring machinery are not addressed at all, to say nothing of humans needing to be focused on a project for millions of years. I'm saying not possible for social, political and economic reasons, it's not how humans act.
Drake Equation (Score:2)
Guesses (Score:2)
So... (Score:2)
since we started making cosmic call in 1970 we can expect a return message ( assuming the average is correct ) in 2*17000 34000 years, if it is recognized and if we are still here to hear it. Assuming of coarse other civilizations have not figured out a way to overcome the speed of light.
"Most Likely" is a misstatement (Score:2)
What they meant to say was "we pulled a bunch of wild assumptions together with a few more wild assumptions did some magic math and got a number.
We have observed exactly one planet with life and that planet has a civilization on it. To extrapolate anything to the 100's of billions of start systems in the galaxy is ridiculous.
We have not even confirmed the longevity of contactable life on the one planet we know about. The way things look the time from developing radio to making the planet uninhabitable could
Re:Can you hear me now? (Score:5, Insightful)
No human technology exists, and we think it cannot exists because we still don't know everything.
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No technology exists as allowed by the laws of physics and economics as we currently understand them, which are presumably the same for everyone.
FTFY
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