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https://i.imgur.com/BV44hP9.jpg
An artist's concept of Kepler-186f, discovered in April 2014.

Last week, scientists announced the discovery of Kepler 186f, a planet 492 light years away in the Cygnus constellation. Kepler 186f is special because it marks the first planet almost exactly the same size as Earth orbiting in the “habitable zone” – the distance from a star in which we might expect liquid water, and perhaps life.

What did not make the news, however, is that this discovery also slightly increases how much credence we give to the possibility of near-term human extinction. This because of a concept known as the Great Filter.

The Great Filter is an argument that attempts to resolve the Fermi Paradox: why have we not found aliens, despite the existence of hundreds of billions of solar systems in our galactic neighborhood in which life might evolve? As the namesake physicist Enrico Fermi noted, it seems rather extraordinary that not a single extraterrestrial signal or engineering project has been detected (UFO conspiracy theorists notwithstanding).

This apparent absence of thriving extraterrestrial civilizations suggests that at least one of the steps from humble planet to interstellar civilization is exceedingly unlikely. The absence could be caused because either intelligent life is extremely rare or intelligent life has a tendency to go extinct. This bottleneck for the emergence of alien civilizations from any one of the many billions of planets is referred to as the Great Filter.

Are we alone?

What exactly is causing this bottleneck has been the subject of debate for more than 50 years. Explanations could include a paucity of Earth-like planets or self-replicating molecules. Other possibilities could be an improbable jump from simple prokaryotic life (cells without specialized parts) to more complex eukaryotic life – after all, this transition took well over a billion years on Earth.

Proponents of this “Rare Earth” hypothesis also argue that the evolution of complex life requires an exceedingly large number of perfect conditions. In addition to Earth being in the habitable zone of the sun, our star must be far enough away from the galactic center to avoid destructive radiation, our gas giants must be massive enough to sweep asteroids from Earth’s trajectory, and our unusually large moon stabilizes the axial tilt that gives us different seasons.

These are just a few prerequisites for complex life. The emergence of symbolic language, tools and intelligence could require other such “perfect conditions” as well.

Or is the filter ahead of us?

http://mashable.com/2014/04/23/habitable-planets-human-extinction/

Or a more reasonable explanation: it is very hard to cross interstellar distances. There could be intelligent life on Kepler 186f right now, but there is no way for us to contact them and there is no way for them to contact us.

We could design a vehicle that would go explore there (maybe using solar sails and gravimetric acceleration slingshotting around intervening stars), but it would still take millennia to get there. Maybe they sent an exploratory probe when they discovered the earth millions of years ago, but it came by 400 years ago and we missed it. Maybe they are not as developed as we are? Maybe there is intelligent life there, but they just are not interested in astronomy?

Earth: "Knock! Knock!"

500 Light years later

Kepler 186f: "Who's there?"

500 Light years later

Earth: "Who are you again?"



If life is bubbling across the universe just like it is bubbling all the time here on Earth, then maybe the civilizations who survived that "filtering" would not be bothered communicating?

Perhaps we are the first technical civilization in our galaxy? Someone has to be the first.

That is a possibility. Let's say another Earth roughly of the same age is withing our galaxy. The only difference is that other Earth was never hit by a killer asteroid. Ever.

It could mean that being killed almost to the point of extinction over and over is a good thing if an ecosystem wants to go beyond its dinosaur stage.

Ah, very unlikely.  The theory of stellar evolution indicates that many generations of star systems - with planets - have come and gone.   

Some of those you can reckon had smart folks.  Where did they go?  Assume, for the moment that interstellar dust makes physical travel between star systems pretty much impossible.

Where, indeed?

They do not talk with us just like we do not talk with bugs...

For me this paradox seems like a "Post hoc ergo propter hoc" kind of statement. If some species were to become capable of spaceflight only after they got themselves destroyed, it doesn't mean that the destruction is an exact consequence of space travel efforts.

If you believe in Darwin's Evolution theory and push it to its logical limit, a massive destruction of an ecosystem to the brink of extinction will help that ecosystem to evolve to the point of space travel. The memory of random deaths, over and over would be part of the DNA of that ecosystem pushing it, generations after generations to find a way for an ultimate survival solution, away from its home planet... Exactly what we do now. Because we have the knowledge we can be gone for good, leaving behing no trace of our existence.

Or have we always been?

This theory also looks plausible to me: vast majority of technical civilizations tend to destroy themselves, or get destroyed by some cataclysmic event like for example large meteor hit, or simply degenerate and die off before being able to develop efficient methods of interstellar travel. Rare ones who survive and succeed in this venture evolve so much afterwards (in terms of both biology and technology) that they take forms far beyound our comprehensive capabilities, and as such they might not be interested at all to establish contact with young and comparably primitive civilizations like ours. As Spendulus said: they do not talk with us just like we do not talk with bugs  :)

Meaning that at least one ancient and extremely advanced galactic civilization may be all around us, but we are not aware of its presence. Perhaps we're even seeing it, but we just don't understand what we see.

And the Universe is too old for us to be first.

Gotta gree with you, i don't belive we are first technical civilization there must be someone outside there.

There is a possibility that no advanced alien cultures exist because they all invented high energy particle accelerators before becoming space-faring civilizations.

http://press.web.cern.ch/backgrounders/safety-lhc

There really is possibility that life exists somewhere in universe apart from earth but there is no way we'll ever prove it before doomsday.

The argument that you present is fatally flawed, and here is why.  Take a look at the time sequences contained in it.

Time 0:  No Earth style exo planets have been found.

Time 1:  Earth style exo planets FOUND!

Prior to time 1, a valid argument would be "Maybe there are no aliens because conditions for life don't exist".  After Time 1, that cannot be said.  The argument shifts to "But why haven't we seen them?"

Maybe because you just got the first glimpse of the planets that might have created them?  They are, you know, somewhat smaller than the planet.  Now when you can read license plates on exo planets, then let's talk about whether you found aliens or not.

Yes, you need an optical interferometry based telescope array on the Moon or in orbit to do that kind of crazy shit.

Since no one knows when doomsday will happen we may have the answer before it too. The next generation of planet hunter is ready to go in 2017. Unless Putin and Obama decide otherwise...

https://ca.news.yahoo.com/blogs/geekquinox/nasa-next-gen-planet-hunter-root-nearby-habitable-133506592.html

One question is how many cycles are needed to produce sufficient amount of materials needed for interstellar travel? That is heavier metals and such. Or are those needed at all?

Or maybe we just don't know how to identify their communications...

I know when it will happen.  Not a time but I know when.

I never thought much of the "habitable zone" theory. We have no idea what life really likes. We only have one example to look at, and for all we know it is a weird example. Perhaps it is more common for life to exist on stars than planets? or maybe the ultra-cold areas of deep space is where most life exists? 

Correct.  I have a rather fascinating book which is a compilation of tech articles on 'finding et' dated late 1960s.  EVERYTHING IS DATED TO THAT VIEWPORT!

There are serious math analysis of how ET would send a television signal, for example. 

Today we would try to figure how ET would send a router signal.

Tomorrow...

wise conclusion... maybe "they" are around... humans tend to think in 3 dimensions,,,
the other question how could humans become interstellar if humanity is devided like it is...

I am personally not convinced that interstellar travel is possible with mechanical creations such as what we think of as "spacecraft".  The speeds required for such travel are so high that even dust impacting would be power of atomic bomb.  

I have read proposals for the engineering and operation of such vehicles and frankly, it seems like something that'd be very risky.  Maybe you get to Alpha Centauri in a couple hundred years, maybe the ship vanishes without a trace after a random impact.

Personally (in the "belief" category) I think there are very likely decodable data streams that we could detect and learn very interesting things from and here is why.  

We are now detecting exo planets which are possibly life substaining, this means our planet has long ago been detected as such a place by the hypothetical THEM.

So we don't know if THEY are out there.  And THEY might or might not know that WE are here.  But it would not be difficult to rotate a high power transmitter in the direction of each of 1000 likely exo planets.  Or 100,000.  Consider if one year 7200 hours transmit for 5 minutes to each of 100,000 exoplanets.  Hundreds of years later you get a reply.  When a reply occurs set continuous streaming.  Thousands of years later you have a nice little community.  A little corner of the galactic party.

This works both ways - first, locate the exo planets, then point sensitive radio and light band receivers at those locations.  This is very different than the random searching of the skies which we have been doing.  Then, find a signal.  Etc, Etc...

If we cannot move beyond what we know now, i.e. our total amount of scientific knowledge of what "What" is made of it is not even necessary to contemplate interstellar travel from anyone, us or THEM.


                                  http://s24.postimg.org/a00sn43tt/okmomo.jpg (http://postimg.org/image/a00sn43tt/)
So... Is the speed of light our ultimate prison guard forever?
                       

Although our future as possible spacefaring species may look a little bit grim these days, when 3/4 of humanity is still struggling to survive living in the dirt from day to day, while in the same time the most important thing for 1/4 is to learn what some clown has said or worn, and only technological progress they know is newest model of cell phone or bigger TV screen, we shouldn't forget Carl Sagan and his eternal optimism:

Gee, I don't know.  There is a long illustrious history of prison guards being bribed, cajoled, or blackmailed into working for the team.  Now I can't help but think little Ms. Lightspeed could be influenced to look the other way sometimes....

I'm on the other side of the fence.  I believe the fact we haven't been contacted by an alien race is proof that faster than light travel (for mass) is impossible.

somewhere i did read that 95% of our surrounding is dark matter... 95% so the computer/desk you sit on only represents 5% of matter.... what are the other 95%... maybe its like in matrix that we only think we sit on a computer/desk..
like i said humans tend to think in 3 dimensions...

IMO, the conditions necessary for intelligent life is extremely rare. Despite this, given the vastness of the Universe we should still be able to find this 'other' life right? Well, from what I can see - there could be a number of reasons for our failure thus far:

1. There is life but the lifeform is not advanced enough to send us or receive our messages
2. The lifeform could simply be a microbe which we would have no hope of seeing given our supreme distance from any noteworthy planet
3. Life exists beyond the observable Universe and as a result of space expansion at greater than the speed of light we will never see nor reach them

I'm personally inclined with the latter - either that or since we're getting light from a planet like 500 million years back the lifeform may exist now but at that time didn't.

We may find one day there is a form of life that only exists withing the dark matter. The same way we found those amazing tube worms way down the ocean floor, not using the sun and natural light as a source of energy but something very alien to us, humans, forest, microbes, rabbits, living on the surface of Earth.
But since we exist withing those 5% of what we define as matter, and if everything is made out of the same thing across the whole universe, even if you multiply the unlucky number of many worlds who got hit by killer asteroids, or destroyed by gamma ray burst, you still get that huge number of the possibility of life on many worlds.

The question is why haven't we heard about them yet?

Humans have not been listening to the "space" long enough to take that time into consideration and a prof that aliens do not exist. Let's put it like this. If i live on an island in some ocean with 100 other people and the closest land is 6.000km in any direction, chances that me and my "friends" will find any other life are slim ( considering we still havent discovered planes, boats that can cross oceans ). In that case my enitre life I would thing that we are the only humans.

If theory that nothing can travel faster then life is true then chances that we find prof on an alien life are even slimmer. We are not listening to the stars long enough so we cant say that we are 100% certain that we are the only intelligent life in universe/galaxy. Looking at one Exoplanet today and not "hearing" anything doesn't mean that id didnt had intellignet life or it has it now. From that planet you mentioned for anything to come it would take close to 500 years and that is a long time. 5 centuries ago we couldn't even dream of flying and look at humanity now. What if 500 years ago they were at same level of technological development as we were or even less developed.

So no, it's not even remotely a prof of anything....

But now we have detected exo planets similar to Earth.  And that will continue, now that we know how to do it.  After a while, we'll have - let's say - a list of 100 such planets.  We can aim DIRECTIONAL recievers at those points.

Right now we are just randomly pointing antennas around hoping to maybe pick something up.  With radio that doesn't work too well.  You'd never hear or talk to the Mars rovers unless you had extremely narrow directional antennas.

And obviously to listen to another star system, the problem is that much worse.  We do have some good guesses as to what frequencies to listen on, but have not to this time, known WHERE.

This is just more of the same from people who will refuse to believe anything good can come from us believing others could exist in the universe beyond us.  Or that we have the potential to grow as a species and populate other planets.  it's all this negativity and babble that people make up to keep themselves and other in the dark that is really killing progression in my opinion.

And how will that help? There are billions of planets in our galaxy alone, what are the chances that those planets would have intelligent life? Less then winning a lotto 3x in a row. You are forgetting many things, and one of them evolution and technological develepment. Being a planet that can sustain life doesnt equal intellignet life has yet evolved or survived, or taht species is capable to emit radio into space. And we as humans have been brought to near extinction many, many times... And dont forget that human made radio wave has traveled about 100 LY so far ( furthest ), so if lets say there is an intelligent life on that Exoplanet listening to our part of the galaxy ( pointing radio waves to our planet ) he wont detect ANYTHING.

Do you believe that aliens still using radio signals? Our race just started using electricity few hundreds years ago. Imagine some other civilizations have existed for a millions years. Their communications would not be detected if they would not to. We will not detect their presence if they will not to. They will be like god. There is a possibility that we are only a simulation on their computers.

A few hundred years of electricity eh?   ;)

You're right about the radio signals.  We started those last century and already turned most of them off.  All the US and Canadian TV signals are digital now (ignorant about the rest of the world).  What are the odds that an alien race turned their radio telescopes to us in just that short period we were transmitting?

Me neither. And what if there's another 'humanity' that looks different from us? Not your alienish one. That would be rather interesting, yet scary. What humanity is capable of now, is scary. What another humanity might be able to do, possibly a more intelligent one, is scary.

If we are scared, should we stop looking? I am sure THEY won't until they found us

You misunderstand.  I suggest not that an ET would hear anything from us, but that signalling from, to and between ET would be by narrow beam communications.  Of what type?  Does not really matter.  Narrow beam requires knowing where to point, so ET(planet 937) would point at what he considered habitable planets.  Because of some details of chemistry, water is most suitable, so he would have had a beam pointed at Earth.

How would you detect it?   You'd crank a directional antenna around in turn between planet 0...999, and when you hit 937, you might pick it up.  If you did, you just hit the jackpot.  Because that repeating broadcast from ET would contain the details of how, where and when to communicate.

It is simply not proof.  As a way of looking at this, let's first assume that the universe is rich in consciousness.  That there are millions of races of ET.  They seek to communicate and learn, they are curious. 

This gives you the position with the most weight in favor of your argument.

But FTL could simply be highly risky.  It could be hugely costly in terms of energy expenditure.  It could only go between certain points in the universe, not anywhere.  There could be limits to the size or mass moveable through FTL.  So forth and so on.  None of these meet the criteria of "impossible", yet they all would in a practical sense explain why physical ET has not been seen around these parts.

Then again, for most of human history man has been steeped in myth and superstition, and ET could easily have visited and would have fit right in as a god, a devil, a spirit, or any of a number of things that man had working frames of reference for. 

So you can't support the premise nor the conclusion.

I read before that there are billions of stars in our galaxy. And only 1,000,000 systems located in goldilocks zone like our sun that can support life. Our galaxy has a diameter of 100,000 light years. It its calculated that the nearest possible civilization is within 1000 light years. That civilization can be a million ahead of us or million years from now. The possiblity of each civilization to contact each other has a very small chance.

We are using radiowaves the same speed as light. If we are contacting a civilization from 1000 light years away. It take 1000 earth years for our message to reach them. If they reply immediately assuming they are listening to us it would take another 1000 earth years, for their message to reach us. And we don't have the machine yet and the energy needed would be tremendous. And how would we communicate them?
 

Hundreds of billions.    ;)

I know what are you trying to say but you need to take into calculation time since it plays HUGE part in detecting intelligent life. If that planet 973 has intelligent life that is at same level of technological level as we are then we wont be hearing form them in centuries. Radio waves travel with the same speed as light so if they are 900 LY away and they sent signal 100 years from now we wont hear it in another 800 years. And if they are millions of years ahead we probably will never figure out they exist. But what if that planet has intelligent life but they are in stone age?

Thing that should also be taken into consideration is the fact that we are very, very young technical civilization. Earth is hosting life for 4 billions of years, homo sapiens may have been around for 200.000 years, and yet we've discovered radio 100 years ago and radio astronomy just 80 years ago. Hell, all our recorded history is barely 6000 years old. That's really miniscule timespan when put into the cosmic scales. Plenty of interesting events may have happened which went unnoticed or in best case misunderstood, as they may be happening right now too.

Well, let me give you a more plausible case.  100,000 years ago numerous advanced civilizations in the galaxy set up transmitters pointed to identified life-capable exo planets.  Some died or were wiped out, but others continued the transmissions using the same formula   The transmitters were to run indefinitely and transmit a repeating broadcast with specific info on where to look in the sky for information broadcasts.  All broadcasts are one direction, transmit only.  Like our DirectTV satellites, you might say.

We discover exoplanets, we point our sensitive antenna at them and suck up a couple of broadcasts.  Decode them, perhaps build the necessary equipment, and VOILA!  We are hooking into the galactic DirectTV, baby!  Cool!

Now, you see, "time lag" does not really matter.

Some years/centuries/millenia later, perhaps we choose to set up our own transmitter.

TV noise is not TV Noise - it is remnants of the Space Reptilians and their intergalactic communication network.  Shsss... psssfttt... gsssssk...   We just assumed it was background noise the entire time because it was there since the beginning.

And why do you think that after 100,000 years ago they are still searching for intelligent life or that if they are wiped out/extinct their radio equipment is still active after all those years?  Time lag is crucial, you can't neglect that and say oh well who cares. Assume that some alien race 100,000 years "older" and more advanced then us, why d you think they will search for intelligent life so low on a technological level? The difference between us and that alien race in technology is so great that that alien race wouldn't be interested in "talking". And even if they are interested they would be looking for signs of current communication not possible one in xyz years. They find exoplant, listen fo few week, they dont hear anything and move along, same as we are doing. And if they are so advanced that they discovered how to harness the power of Tachyons ( assuming they exist ) there is no chance for us to speak to them or detect something we are not even sure exists, and if you think alien race so advanced would use sublight speed communication, then thats just wrong.

And why do you think that after 100,000 years ago they are still searching for intelligent life or that if they are wiped out/extinct their radio equipment is still active after all those years?

Some might, some might not. 

Time lag is crucial, you can't neglect that and say oh well who cares.

Time lag is not crucial it is irrelevant for one way transmission.  It is relevant for two way conversations, yes.

Assume that some alien race 100,000 years "older" and more advanced then us, why d you think they will search for intelligent life so low on a technological level?

Broadcasting is different than searching.

The difference between us and that alien race in technology is so great that that alien race wouldn't be interested in "talking".

Right.  So Europeans were not interested in talking with American Indians.  Wrong....

And even if they are interested they would be looking for signs of current communication not possible one in xyz years. They find exoplant, listen fo few week, they dont hear anything and move along, same as we are doing.

Assume that some number of ET are/have been doing this.  So there exists something like a bunch of cable TV channels and data feeds they can tune into.  If one goes dark, then flip channels.

And if they are so advanced that they discovered how to harness the power of Tachyons ( assuming they exist ) there is no chance for us to speak to them or detect something we are not even sure exists, and if you think alien race so advanced would use sublight speed communication, then thats just wrong.

I mentioned that the basic repeating broadcast sent the life-capable exoplanets would be in radio or light narrow beam comm channel.  Why?  Well, because that's the basic signal by which the universe presents itself to our senses.  There have been studies made of the likely/most probable frequencies which would be used which make sense.

So yeah, the initial message received might be how to build the 'more advanced receiver' that was required to actually link into the galactic network.

The answer to the Fermi Paradox is that we're living in a computer simulation, obviously.  :)

http://www.simulation-argument.com/simulation.html

Indeed, we're alone in this simulation. Other solar systems and planets are just a technical trick of the program, designed to be just a red herring. They're projected far enough away from us so that the limits and borders of our world are somewhat believable for us.

but if it is a simulation as some said, what would be the real size of the "universal pixel"?

10 other possibilities...

http://io9.com/11-of-the-weirdest-solutions-to-the-fermi-paradox-456850746

Planck Length (https://en.wikipedia.org/wiki/Planck_length)?

Well, clearly, then the Earth could well be just 6000 years old.  Of course, I never understood how that theory jived with sedimentary rock, but hey, in a simulation, someone could be monkeying with the controls, you know, until one day, we find out and lay some traps for the bastard.  And let me tell you, he's gonna be in deep shit then.  

And maybe he didn't know what that even was, being off there in that realspace and we down here in simulcra.  

And that's the problem with that hypothesis, isn't it?  That elsewhere is the real.

https://i.imgur.com/fmNqKVp.jpg


Goldilocks zone

Perhaps the most habitable planet found to date is the recently announced Kepler-186f. This is one of five exoplanets discovered by NASA’s Kepler satellite, all orbiting a small, faint, red dwarf star, 500 light years away in the constellation of Cygnus.

Kepler-186f is an Earth-sized planet that orbits its star in only 130 days and is about as distant from its star as Mercury is from the Sun. But because the red dwarf is much dimmer than the Sun, Kepler-186f receives only about one-third of the energy that the Earth does. As a result, Kepler-186f lies at the outer edge of its star’s “habitable zone.” This is the hypothetical region of space surrounding a star in which liquid water may conceivably exist on the surface of any exoplanets.

In our own Solar System, Venus lies too close to the Sun and is too hot. Mars lies too far from the Sun and is too cold. But Earth, of course, lies within the critical “Goldilocks zone,” where the temperature is just right.

Simply residing in the habitable zone, though, is no guarantee that an exoplanet has water oceans. The climate of a planet is much more complicated than what we can capture with a simple calculation based on the distance of a planet from its star. We know that Mars probably had running water on its surface in the past, but now it is a frozen desert. Earth, meanwhile, was probably in a completely frozen “snowball” state about 650 million years ago.

Even leaving aside questions of climate, not all exoplanets have a surface on which liquid water could exist. Many of the exoplanets found in the past 20 years are massive, Jupiter-sized planets. This is not surprising, as bigger planets are easier to find (even if they are not the most numerous). But a Jupiter-sized exoplanet in the habitable zone of a star is unlikely to have liquid water, much less prove a suitable habitat for life as we know it. Jupiter has an outer atmosphere of gaseous and liquid hydrogen overlaying a metallic hydrogen envelope that extends for thousands of kilometers. Any rocky surface is confined to a core buried under millions of atmospheres of pressure.

But if a Jupiter-like exoplanet orbits within a star’s habitable zone, it begs the question: might that exoplanet host habitable moons like the Ewok’s home? Jupiter has Europa, which is suspected to have liquid water buried under an ice crust, and Saturn has Enceladus, which definitely has water hidden underneath its coat of ice. So Earth-like exomoons are certainly not out of the question.

http://arstechnica.com/science/2014/04/move-over-exoplanets-exomoons-may-harbor-life-too/

yeah i think most planets and intelligent life probably go through same cycle as we do.. and up killing themselves.

also, humans/intelligent life on earth have only existed for 200,000 years, while the planet's age is 5 billion years old. on a cosmic scale, that's the equivalent of.. 1/500th of the planet's history. of that 1/500th of earth's history, we have lived for 99.9% of it unable to send out signals for other intelligent life.