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Detectable Civilizations in our Galaxy 4 : Taking a shot at estimating the number of detectable civilizations
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- I have talked a bunch about the Drake equation or our own version of the drake equation
- that starts with the number of stars in the galaxy.
- But I haven't given it a shot yet
- I haven't tried my own attempt at thinking about
- how many detectable civilizations there are
- So lets actually do that here
- so lets just assume there are one hundred billion stars
- so that's my first term right over there
- lets say that one fourth will develop planets
- and lets say of the solar system that develop planets
- on average 0.1 are capable of sustaining life
- or you will have one planet for every ten of these
- solar systems with planets
- that's just my assumption there
- I don't know if that's right
- now lets multiply that times the fraction of these
- planets capable of sustaining life that
- actually will get life
- And I don't know what that is
- but I hinted in previous videos that
- life is one of those things that it seems as if you have
- all the right ingredients it's so robust that you
- have life at these underwater volcanoes
- you have bacteria that can process all sorts of weird things
- so lets say that probability is pretty high
- lets say that is fifty percent
- or half of the planets capable of getting life
- actually do have life
- I would guess that might even be higher
- but once again
- just a guess
- now we have to think about
- of the life what fraction becomes intelligent
- what becomes intelligent over some point in the history
- well I will say its a tenth
- well maybe if the asteroid didn't kill the dinosaurs
- then it wouldn't have happened on earth
- or maybe we might just have had very intelligent dinosaurs around
- we don't know
- so maybe there might be other forms of intelligent
- life that we haven't fully appreciated
- dolphins are good candidates
- some people believe that octopuses
- because they have such flexible arms
- there's a theory that they could develop eventually
- the ability to kind of
- one day if their brains mature
- and all the rest
- make tools the same way primitive primates
- eventually were able to have larger brain sizes
- and actually manipulate things to make tools
- so who knows
- I don't want to get into all that
- so there's a one in ten chance that you get intelligent life
- and then assuming that intelligent life shows up
- what fraction is going to become detectable
- I don't know
- I don't know whether dolphins will ever communicate
- via radio or not
- so lets just say that is another one in ten chance
- or I will say 0.1
- and then we have to multiply times the detectable
- life of the civilization
- on average
- once again huge assumptions being made here
- but the detectable life of a civilization
- let me just put it at ten thousand years
- either they destroy themselves
- or they go beyond the radio type of communication
- electromagnetic type of communication
- maybe they start all sorts of weird wacky things
- probably won't even take ten thousand years
- to even progress at that
- might take less time
- but lets just do this for the sake of fun
- and then the lifespan of your average star
- that's probably one of the things that we have the best sense of
- so on average lets put it at ten billion years
- so lets calculate all of this
- lets get my handy TI 85 out
- and so we're going to have one hundred billion
- thats one times ten to the ninth
- sorry no thats one hundred times ten to the ninth
- so let me clear it
- or you can have one times ten to the eleventh
- that is a hundred billion times 0.25
- times 0.1 times 0.5 times 0.1 times 0.1 again
- times ten thousand divided by ten billion
- so times ten thousand divided by ten billion
- so thats one "e" ten
- one times ten to the tenth power
- one with ten zeros
- so lets see what we get
- we get 12.5
- which is kind of a neat number
- but you know these are heavily dependent on this
- so we'll say that given all these assumptions
- there should be 12.5 detectable civilizations
- in our galaxy right now
- so the questions is why aren't we detecting it
- maybe their radio signals or electromagnetic waves
- are getting to us but we can't differentiate
- it from noise right now
- and that's what the SETI project is all about
- trying to keep track of all this information
- all the radio and electromagnetic waves coming from
- outer space and towards earth
- and seeing if any of them actually have
- any non-noise signal
- that actually look like they are being generated
- by some type of intelligent civilization
- so maybe we are getting them
- and just not detecting them
- or maybe something else is at play
- maybe we have over estimated one of these
- maybe there is a lot of life
- but maybe they are not using electromagnetic
- waves to communicate
- maybe that's some sort of primitive way of communicating
- maybe they start doing telepathy or something crazy
- or they started using some quantum thing
- that allows them to communicate more directly without
- having to wait for the speed of light
- they might view that as a very slow way to communicate
- and it is frankly a slow way if your trying to communicate
- across solar systems and stars and planets
- or even across galaxies one can imagine
- so maybe we are in a transition state of communication
- that electromagnetic waves
- radio and all the rest is just a transition state
- maybe in a hundred years we'll figure out another
- better way that's not detectable in our traditional ways
- maybe we are being bombarded by another type of
- communication mechanism which we are not ready
- to perceive yet
- who knows
- but its just a fun thought experiment to just say that
- hey given these assumptions there should be at least
- a couple of civilizations or a handful of
- civilizations that we might be able to detect
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