# New Estimate on likely no. of alien civilisations in our galaxy



## Serendipity (Jun 15, 2020)

See Scientists say most likely number of contactable alien civilisations is 36


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## The Judge (Jun 15, 2020)

I'm disappointed it's not 42...


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## Elckerlyc (Jun 15, 2020)

To quote from this article: “They would be quite far away … 17,000 light years is our calculation for the closest one,”

Contactable? How are we going to contact these civilizations? Any Q&A will take 34000 years. Our civilization will be gone before the answer arrives. And all this doesn't answer the question were all the life-signs from older civilizations are.
This number is so theoretical, it's basically meaningless. IMHO.



The Judge said:


> I'm disappointed it's not 42...


Likewise! It must be an error...


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## Justin Swanton (Jun 15, 2020)

The real problem is the impossibility of communicating with any hypothetical alien civilisations should they arise. The laws of physics apply everywhere in the universe: there is a draconian limit to how far communication signals can be transmitted and still be discernible against background radiation. Military radars - each costing hundreds of millions of dollars - are by far the most powerful signal transmitters ever constructed, nonetheless their maximum range is about 200 light years. And we're talking about hypothetical civilisations living thousands of light years away. So in all probability, even if they are talking to us we will never hear them.

Sure, we could beggar the world economy by building a far more massive transmitter, but why would we do that? It would take centuries or millennia to get a reply and by then the civilisation that constructed the transmitter will be long gone. Technological advances aren't going to change things - a powerful signal needs a powerful energy source, no matter how sophisticated the tech. You *could *try the Moties' lasers, but they need to be aimed at a single planetary system that also isn't too far away. Which one if you don't already know where life is?

Sorry about the cold water.


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## Astro Pen (Jun 15, 2020)

Despite the fact that it negates half my literary output I suspect that their figure is out by 35.
You need a lot more than mere habitable zones and active biology. 
Opposable  thumbs, farming, a sweet spot oxygen level that supports fire but doesn't  torch everything and a Francis Bacon, to name a handful from thousands.
Of course it is possible that herds of wildebeest will eventually produce aluminium alloys, calculus  and semiconductors but I'm not banking on it


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## Ori Vandewalle (Jun 15, 2020)

I don't think we know the full breadth of possible conditions that could support intelligent life. We know present Earth is in the space of possible conditions, but N=1 statistics are notoriously poor.


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## Parson (Jun 16, 2020)

Ludacris to even hazard a guess. The only true answer is "We don't know." ---- And it corollary: "It's anyone's guess."


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## Danny McG (Jun 16, 2020)

Astro Pen said:


> Of course it is possible that herds of wildebeest will eventually produce aluminium alloys, calculus and semiconductors but I'm not banking on it


That's my sci fi dream ruined then.
*Gutted!*


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## tegeus-Cromis (Jun 16, 2020)

Parson said:


> Ludacris to even hazard a guess. The only true answer is "We don't know." ---- And it corollary: "It's anyone's guess."


I totally agree. But what I really want to say here is, "Why, I had no idea you were a hip hop fan, Parson!"


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## Ori Vandewalle (Jun 16, 2020)

Reading through the paper, most of the work is in calculating the current number of high metallicity stars more than 5 billion years old and the number of Earth-like planets in the habitable zone of said stars. The former they estimate by looking at the star formation history of other galaxies (mirroring our own galaxy at younger ages). The latter comes from Kepler data.

The "Astrobiological Copernican Principle" isn't the main thing; it basically amounts to setting the "fraction of habitable planets that give rise to aliens with radios" terms from the Drake equation to 1. They're pretty upfront about the limits of the whole approach, though. From the paper: "The traditional approach toward examining whether CETI have formed in the Galaxy has been proposed through the use of the Drake equation (Drake 1965). This has remained the primary method for inferring the likely number of CETI in our Galaxy, yet it is fundamentally an unsolvable equation (prior to any extraterrestrial life being found)."


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## Biskit (Jun 16, 2020)

Elckerlyc said:


> Our civilization will be gone before the answer arrives.


I'm sorry, that's just the reality of any customer help-line.

"Welcome to the Zargian Empire. Your call is important to us and you are 16,000 lightyears into the queue. If your enquiry is not urgent, press one now and a warship will get back to you as soon as it is available..."


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## Parson (Jun 17, 2020)

tegeus-Cromis said:


> I had no idea you were a hip hop fan, Parson!"



I sure am a hip hop fan. You should see me with my 3 year old granddaughter. We hip and we hop.


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## Great Boo (Dec 14, 2020)

There is a widespread fallacy concerning ‘teleology’, the concept of the universe working towards achieving goals, including the idea that all life strives onwards and upwards from lower to higher, and from simple to complex. It is seen in the false but widely believed-in cartoon image of the evolution of man (and it is always man, not woman) as progressing from lemur to monkey to ape to ape-man to stone-age human to modern man, getting bigger and more upright (and whiter) as the progression develops. But this image is completely false. Monkeys are still here and they are doing just fine, they have never thought of themselves as an imperfect stage on the journey towards humanity, because they are not one. Evolutionary pressures often lead to lineages becoming more simple or smaller. There is absolutely no reason in the universe for ecosystems to strive towards technological intelligence. It isn’t a goal and ecosystems don’t strive.
The Drake Equation is firmly embedded in the teleology fallacy, and assumes that technological intelligence is a goal that ecosystems will work towards if they can. That’s the whole point of estimating the fraction of life-supporting planets that form life, the fraction of those living planets that develop intelligent life forms, and  the fraction of those intelligent life forms that develop technology. But this is bad science. The tetrapod body plan of lizard-like proportions, with a large body and a small brain, was hugely successful for hundreds of millions of years, and still is successful in crocodilians and reptiles. No dinosaur line felt any evolutionary pressure to develop technological intelligence. It isn’t necessary for survival if you are a dinosaur, and that’s the only evolutionary pressure there is.
For some reason, our ape-like ancestors became the first organisms in the history of life to experience strong pressure from generation to generation in which the most intelligent survived at the expense of the least intelligent, in one lineage for long enough that our species eventually developed technical civilisation. Even so, Homo erectus was globally successful for two million years, lasting far longer than it looks like we are going to. There was no pressure on any Homo erectus line to develop a technological civilisation, so none of them did.
Evolution is the word we use to describe what’s left after everything else is dead. It isn’t a teleological process and it isn’t striving towards a goal such as technological civilisation. Genetic lineages develop and diverge as they experience different circumstances in which different factors lead to survival, such as long noses, large size, fast running, small size, camouflage, ability to breathe on land when the river dries up, and so on. If our line experienced pressure to become less intelligent, it would have done so. It is quite possible that the common ancestor of humans and chimpanzees was more like us than like modern chimpanzees, and that the savage wild animals in the jungles of the Congo have become like that over time because that was how to survive.
Ecosystems won’t develop technological civilisations unless there happens to be a unique set of circumstances that promote long, slow development of brains, language and intelligence. It’s certainly not something that will happen wherever it can happen, because it isn’t a goal that life is striving for.
Even if there are millions of complex ecosystems out there in the universe, technological civilisations will develop if and only if there is long-term pressure on genetic lines to develop technological intelligence, and if and only if those intelligent species have the physical ability to make and build, experiment, develop agriculture, medicine… There is no reason to think that such pressures should ever occur under standard circumstances.
They might. However, the comment in the article by Dr Patricia Sanchez-Baracaldo saying “But, yes if we evolved in this planet, it is possible that intelligent life evolved in another part of the universe,” is a reiteration of the medieval scholastic statement “ab esse ad posse valet consequentia”, that is, “from the fact that something exists, it follows that it is possible for it to exist.” Scholastic philosophy was never very impressive, and it doesn’t tell us anything important here.


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## Astro Pen (Dec 14, 2020)

I suspect that language is key to technological development. Once any species has a speech centre, language enables the description and transmission of ideas. In some way the 'logic of language' creates a new type of thought which can construct and extrapolate far beyond the immediate.
Language's close relative, numeracy, enables precice experimental thought and mental model making, moving from shells and beads to calculus. These lead almost inevitably to technological progress. Starting, very often, with an odd fusion of religion and number creating a cultural imperative to predict star and planetary movement.
( The Antikythera mechanism)


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## Great Boo (Dec 14, 2020)

Astro Pen said:


> I suspect that language is key to technological development. Once any species has a speech centre, language enables the description and transmission of ideas. In some way the 'logic of language' creates a new type of thought which can construct and extrapolate far beyond the immediate.
> Language's close relative, numeracy, enables precice experimental thought and mental model making, moving from shells and beads to calculus. These lead almost inevitably to technological progress. Starting, very often, with an odd fusion of religion and number creating a cultural imperative to predict star and planetary movement.


Yes I completely agree. My point above is that there has to be a survival reason for the evolution of large brains, language and culture in the first place, and if that evolutionary pressure isn't there, then it won't ever happen. Big brains use up a lot of energy, dinosaurs were much happier without them.
But here’s another point. There is growing evidence to suggest that the second most intelligent species on Earth is the humpback whale. These whales demonstrate empathy, awareness of themselves and others and what others might be feeling. They also have long, complicated songs. Their songs do not constitute language, but it is very possible that if humans do the decent thing and exterminate themselves then humpback whales might develop true rational intelligence and true language.
If so, will they develop a technological civilisation? Obviously not, because they can’t make anything. There is no possibility of humpback whales having a Bronze Age, or discovering electricity. They can’t physically do anything technological at all. We can, we have hands. If by pure chance intelligent language-using humpback whale creatures evolve on another planet, they will not develop a technological civilisation.
The universe is very, very young. It's only three times as old as the Earth. I find the chances of anyone else being out there to be vanishingly remote.


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## Montero (Dec 14, 2020)

That is a stunning thought after all the sf I've read with elder races in. Human beings the elder race. Yikes. We have a lot of growing up to do.
Or maybe we are destined for the role of dying out leaving enigmatic remains for future xenoarcheologists from the next race to evolve......


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## Great Boo (Dec 14, 2020)

Montero said:


> That is a stunning thought after all the sf I've read with elder races in. Human beings the elder race. Yikes. We have a lot of growing up to do.
> Or maybe we are destined for the role of dying out leaving enigmatic remains for future xenoarcheologists from the next race to evolve......


We won't last long. We certainly won't become a great Elder Race. But it's correct to say that we have a lot of growing up to do. Humans still believe in gods and spirits and engage in religious rites, for goodness sake. 
The best way to think about it is to use the temporal unit of a Grandparent. A Grandparent is 50 years. That's the difference in age between an older member of the family sitting down with the little grandchild and telling them all about what life was like when they were young. There have been ten Grandparents since Shakespeare, forty since the start of the Roman Empire and one hundred since the beginning of human civilisation. That's not very many. We are very young and in many ways very primitive. To get to survive to be an Elder Race later in the lifetime of our galaxy we have to grow up fast, now.


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## Venusian Broon (Dec 14, 2020)

Montero said:


> That is a stunning thought after all the sf I've read with elder races in. Human beings the elder race. Yikes. We have a lot of growing up to do.
> Or maybe we are destined for the role of dying out leaving enigmatic remains for future xenoarcheologists from the next race to evolve......


Actually you may find it a comforting thought, given the "great silence". If you believed a very much more optimistic view of alien technological life, say the original paper giving 36 civilisations out there* and we were the youngest of the bunch, then where are the others?** Yes there are a lot of 'solutions' to the Fermi paradox, but the absence of evidence at the moment, (and assuming the above optimistic viewpoint) then perhaps that means that there is a _great filter_ that stops all technological civilisations getting much further than we've got. And that should be a slight worry   

Or perhaps it really has 'needed' 13.8 billion years for an aspiring interplanetary/interstellar species to come into existence and we are, indeed, one of the first. Hence the lack of anyone else out there. This paints a bit more optimistic future, I feel! 

Anyway the clock is ticking. The sun is getting brighter and more intense all the time and we only have (probably) half a billion years before the surface of Earth will become as hellish as the current surface of Venus. 

====================================================================

* I don't have such an optimistic view. The Great Boo's arguments about intelligence are, I think, part of the answer, but also I suspect that, although there will be a lot of life out there in the universe, it will likely be virtually all single celled forms! Hence I believe that the chances of finding intelligent life forming technological interstellar societies is vanishingly small. However ignoring this for the argument...

** Even if we were stuck with sub-light speeds to travel between stars, a progam of self-replicating Von Neuman machines could, in principle, survey the entire galaxy in a blink of cosmic time - I believe 10 million years is usually given - and although we don't have the technology to do this now, this seems something that I do believe would be possible in the future. So it just required one civilisation to set off such a project that could litter the galaxy with evidence. But even then if that was not the case, a Kardashav type 2 should be reasonably obvious to spot - assuming they build Dyson swarms around their star and that we have powerful enough telescopes to find them.


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## Parson (Dec 14, 2020)

I don't buy the view that religion writ large is a sign of immaturity. Perhaps holding a view that there is something greater than myself and my needs is more a sign of maturity, than of ignorance.

Edit: This is a discussion that could cross the line about what we can discuss on this site. If we start discussing the relative values of certain religions we will find this discussion ended very quickly by the moderators.


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## Wayne Mack (Dec 14, 2020)

Given the distances, I view the argument for intelligent life to be moot. If other life exists, we will never come into contact with it.


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## Montero (Dec 14, 2020)

Unless advances in physics on our side or theirs changes transport enough. All the wormhole theories and the like. I'd never say never. Would agree to "highly unlikely".


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## Parson (Dec 15, 2020)

Or, maybe their society and/or individuals is so long lived that a journey of centuries is not out of the question.


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## J Riff (Dec 15, 2020)

36 with interstellar space travel, more like a twenny thou civilized rocks or dirtballs out there.


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## Astro Pen (Dec 15, 2020)

Fantasy writers, when stuck,  pop up with, "magic". SF writers do not enjoy that luxury. If you are writing FTL, warp drives or  alien military flotillas pitching up here you are suffering, to a degree, from genre slippage. 
It's fun, so we do it anyway, but to pretend that it is in some way projected true science is delusional. Though many believe their own propaganda because physical reality is tediously limiting and means that we really _do_ have to look after spaceship earth very carefully.
Inter galactic traveling biology is  rather like reverse time travel, ( if it were_ ever_ going to be invented it would be here already.) We would have lost our planet to it long ago.  

However, incredible distances, C, and cosmic radiation will stop any interstellar travel for anything but robotics. Even robotics will need to carry a bulky lead overcoat and  some chronologically durable kind of power supply.  
One thing that can be sent at light speed though. - information.  Forget Greys landing in the woods, look for information.


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## Justin Swanton (Dec 15, 2020)

Parson said:


> Or, maybe their society and/or individuals is so long lived that a journey of centuries is not out of the question.



Interestingly enough, that's the theme of my SF novel. My starfaring civilisation *first *made themselves immortal, *then *built an interstellar ship.  About the only remotely feasible way of doing it.

There is one argument against alien civilisations, at least against those capable of interstellar travel. Earth is one of the relatively few planets capable of harbouring life built on hydrogen, oxygen and carbon - the elements in the periodic table that allow for the most complex life forms.

Earth furthermore has been able to support life for hundreds of millions of years. Hence for a very long time it has been a valuable prize for any starfaring civilisation whose molecular biology is built on the same elements. If there was such an alien civilisation they should be here already - in fact they should be in charge (MIB anyone?).

An interstellar civilisation consisting of hundreds or thousands of inhabited worlds could not simply cease to exist, just as human civilisation has never ceased to exist once men learned to till fields and build towns. If the aliens make a mess of one planet they can always find another one to colonise. An interstellar civilisation should exist now if it ever existed in the past.  But there is no evidence for such a civilisation. Therefore such a civilisation never existed.

I don't think alien life exists at all for other reasons that I won't go into here (most of you probably know them already).


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## Justin Swanton (Dec 15, 2020)

Astro Pen said:


> However, incredible distances, C, and cosmic radiation will stop any interstellar travel for anything but robotics. Even robotics will need to carry a bulky lead overcoat and  some chronologically durable kind of power supply.
> One thing that can be sent at light speed though. - information.  Forget Greys landing in the woods, look for information.



Machines actually do very well in space but they can't repair themselves and they can't generate offspring. They have a sell-by date. Re information you have the problem of transmitting a signal powerful enough to cross the impossibly vast distances in the galaxy without getting lost against background radiation. It's doubtful any planetary civilisation could generate the energy necessary for such a signal.


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## Montero (Dec 15, 2020)

Justin Swanton said:


> Machines actually do very well in space but they can't repair themselves and they can't generate offspring. They have a sell-by date. Re information you have the problem of transmitting a signal powerful enough to cross the impossibly vast distances in the galaxy without getting lost against background radiation. It's doubtful any planetary civilisation could generate the energy necessary for such a signal.



We Are Legion We Are Bob has human intelligence copied into machines, and the machines building more of themselves and replicating the intelligence. (Really fun series btw.)


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## Venusian Broon (Dec 15, 2020)

Justin Swanton said:


> Earth furthermore has been able to support life for hundreds of millions of years. Hence for a very long time it has been a valuable prize for any starfaring civilisation whose molecular biology is built on the same elements. If there was such an alien civilisation they should be here already - in fact they should be in charge (MIB anyone?).



I think this is pretty old-hat thinking. It would be far more efficient for a species to convert all the matter of their solar system into billions of 'O'Neil cylinders' or artefacts of the same sort of construction and you would have vast amounts of habitable space, millions upons millions times more area than a single earth-like planet. Put them into a Dyson swarm. Also much easier to adjust to however the star is evolving - for example ours is getting hotter. Even a continent-sized O'Neil cylinder will be easier to change orbit than a full Earth.

Why travel the vast distances to get to another star system only to maroon yourself on a planets gravity well??? (immediately making travelling off and on it incredibly expensive) plus it will extremely likely to need to be terraformed to suit your needs - a process that would take a very long time. Build an O'Neil cylinder instead or Bank's 'Orbital' with exactly what you need. Start small, then build more and bigger.

But fundamentally It would be far easier to make a Dyson swarm in your home system than to colonise another system. Even a relatlvely close one. 

Matter is cheap. Oxygen, hydrogen and carbon is extremely plentiful in the universe. There are asteriods, moons and planets. And if you don't want to take the planets apart there are methods for mining the elements from stars - for example, there exists about 2 earth masses of Gold, say, in the sun. Sure, most of it will be flying about the core but the mining methods could also be used in conjuncture with fusion so that you could build up a whole range of materials that will be useful. And you would get more energy. (Also, although you'd need to extract a huge amount of mass, there is a good reason to 'slim down' the Sun. The smaller the mass of the sun the longer it's age gets, the longer life around it gets time to continue living!)

Of course, we need to learn how to take care of spaceship 1 - Earth - right now. And also hopefully learn how to solve a host of other problems that should be tackeled first - hunger, stopping war, disease, stewardship of the biosphere. And we don't have the technology now, and some of it will take more time to work on, but we're just right at the start of looking at being an interplanetary species.


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