Introduction:
This is a small survey with the aim to establish what people think about the possibility of life elsewhere in the Universe. I know that the true scientific answer many would like to write is that "we don't know", and that's certainly what my colegues and I say to other people for sure. Data is by far incomplete and there is no compelling evidence to assert anything grounded in scientific arguments, but there are educated guesses. Here I'm not allowing any agnostic answer, I want to know what people choose if they are forced to evaluate the odds, so here is the poll.


Questions:
The poll consists of 14 questions/statements you have to rate with a score from 0 to 20 (0 meaning "I absolutely don't believe so" and 20 meaning "I'm certain about it").

• A1) There is or has been extraterrestrial life in the Universe
• B1) There is or has been extraterrestrial life in the Milky Way galaxy
• C1) There is or has been extraterrestrial life in the Solar System
• A2) There is or has been extraterrestrial complex life in the Universe

• B2) There is or has been extraterrestrial complex life in the Milky Way galaxy
• C2) There is or has been extraterrestrial complex life in the Solar System

• A3) There is or has been extraterrestrial intelligent life in the Universe

• B3) There is or has been extraterrestrial intelligent life in the Milky Way galaxy
• C3) There is or has been extraterrestrial intelligent life in the Solar System

• A4) There are different extraterrestrial intelligences communicating with each other in the Milky Way galaxy
• B4) Extraterrestrial intelligence has attempted communication with us.
• A5) There are different extraterrestrial intelligences in contact (physically interacting) with each other in the Milky Way galaxy
• B5) Extraterrestrial intelligence has visited Earth sometime in its past (since the origin of our planet)
• C5) Extraterrestrial intelligence is currently present in our planet or visits frequently (either with us realizing or not)

Procedure and important notes:

• The questions can be answered in this thread or by PM to me (if someone doesn't want to answer publicly).
• The score is not a measurement of how frequent you think something happens but a measurement of how conviced you are something happens at all. For example a score of 18 for extraterrestrial life in the Universe existing doesn't need to mean that the Universe is full of ET but that you are a strong believer that at least once there is ET life in the Universe.

• Some questions are logically related to others, for example if you believe that "there is extraterrestrial life in the Solar System" with a score of 15 it is not very coherent to state that you believe "there is extraterrestrial life in the Universe" with a score of 3. So to guide your final answer bare in mind these constraints imposed by the fact the Solar System is a subset of elements of the Milky Way galaxy that itself if a subset of the elements of the Universe:
  [center][tex]A1 \geq B1 \geq C1[/tex],  [tex]A2 \geq B2 \geq C2[/tex],  [tex]A3 \geq B3 \geq C3[/tex][/center]
• Things like considering a high score for "there is complex extraterrestrial life in the Milky Way" while considering a low score for "there is simple extraterrestrial life in the Milky Way" are logically consistent and perfectly acceptable answers (that would mean that you think that complexity might not only evolve from simple life forms for appear all by itself and even be something more probable). But having a high score for "there is complex extraterrestrial life in the Milky Way" while a low score for "there is extraterrestrial life in the Milky Way" is not logically consistent since complex life is a subset of life (even if it is not a subset of simple life).

Having trouble with the ambiguities? Here are some definitions:

• Extraterrestrial life is not only meant to be life outside Earth (since that would make ISS astronauts fit the description) but also another life form independent of any evolutionary branch of Earth's biosphere.
• Life is losely defined. We are going to consider life any mechanism that can sustainably produce large amounts of entropy autonomosly, that is capable of homeostasis and can grow, thrive, reproduce and die by its own means. In that sense a virus will not be considered life.
• Complex life is life that is built by the cooperation of small living units (like cells) and the distribution of functions between its members to the point that no unit can live long independently. Animals, Fungi and Plants on Earth are considered complex life forms while Bacteria and Archea are not.
• Intelligence means also civilization, the hability to change the the surroundings by will and planning. In this terms not only our species fits the definition but also some sort of artificial intelligence and other hominids (Neanderthals, Homo Habilis etc...).
• Communication attemps in question B4) is regardless of whether we haven't realized, or have realized but not answered, or have answered but secretly, but in question A4) it is meant to be about bilateral communication.

Results:
I'm going to do the exact same pool on Imgur and other social media just to gather as many opinions I can and will show the results next year (probably) in a graphical form here in the forum. If you have any recommendations I welcome any ideas.

Take your time to answer and enjoy the thoughts!

FastFourierTransform, this is a fantastic questionnaire.  Very well thought out.  

I won't take much time to explain my reasoning for any answers, and will just give them in a short format:

------------------------------------------------------------------------------------------------------------------------------------------------------


ETL = Extraterrestrial life
ETI = Extraterrestrial intelligence
uni = universe (presume the observable part)
MW = Milky Way
SS = Solar System


A1 19  There is/has been ETL in uni
B1 18  There is/has been ETL in MW
C1 10  There is/has been ETL in SS

A2 18  There is/has been complex ETL in uni
B2 17  There is/has been complex ETL in MW
C2 6  There is/has been complex ETL in SS

A3 17  There is/has been ETI in uni
B3 15  There is/has been ETI in MW
C3 3  There is/has been ETI in SS

A4 5  There are current ETI comms in MW
B4 3  There have been ETI comms attempted with us

A5 3  There is physical contact between ETI's in MW
B5 3  There was physical contact between ETI and Earth in past
C5 2  There is currently ETI on Earth

Checks:
A1 > B1 > C1 ✓
A2 > B2 > C2 ✓
A3 > B3 > C3 ✓

Some comments and notable correspondences:
All answers are below 20 and above 0.  I cannot be 100% confident for or against anything here.

C3 = B5.  If extraterrestrial intelligence has visited the solar system at any time in its history, I think it very likely would have visited Earth.  This also means that I don't think intelligence arose in the solar system but off of Earth.

20-A1 < C5-0.  I find it less likely that we are the first life to exist in the universe than that we are currently being visited by an extraterrestrial intelligence.  However, I still find the latter pretty unlikely.

B4 is an interesting question and perhaps open to more interpretation. For example, was the attempt at contact deliberately at us, knowing that we are here (my interpretation), or was it a random shout in our direction similar to signals we have cast off toward certain systems already?  If the latter counts, then the value may be higher.

I say 20 for all (19 for last, just to calm waters a little). I've no doubt about this. Even if I was to have a "logical" answer, first question would have been answered with 20 anyway. Why? It's simply crazy to think there's no life outside the Solar System, even in bacterial form, since bacterial life forms can easily be formed (let's not forget, most stars have planets and hundreds of thousands of asteroid-like objects, and only our Milky Way has ~200 billion stars. Just imagine the numbers if we multiply them by several billions more! And we don't even know how big our Universe is and how many galaxies it contains for sure!). 

And I've also been reading every post in this forum for 4-5 years.

A1) 20
B1) 19
C1) 10

A2) 19
B2) 19
C2) 7

A3) 18
B3) 15
C3) 2

A4) 10
B4) 8

A5) 8
B5) 5, but if so, likely millions or billions of years ago
C5) 2

Destrucules from Discord gave these
A1 - 19
B1 - 19
C1 - 15

A2 - 19
B2 - 19
C2 - 11

A3 - 19
B3 - 17
C3 - 5

A4 - 15
B4 - 11

A5 - 15
B5 - 8
C5 - 1

[hr]

Mine would be

A1) 18
B1) 18
C1) 10
A2) 20

B2) 10
C2) 5

A3) 19

B3) 5
C3) 1

A4) 2
B4) 2
A5) 2
B5) 3
C5) 1

It all depends on how likely life is to emerge.
According to my information, the actual origin of life is an absolutely unique, absolutely improbable process that cannot possibly happen a second time in the universe.
But we know that there is life. So the question is, did life originate on earth?
If life originated on Earth, then is the answer:
A1 = 0

But if it originated somewhere else in the universe, and came to earth with asteroids, for example, then the answer is of course:
A1 = 20
(It could also have been brought to Earth by extraterrestrials who forgot the remains of their breakfast when visiting Earth.)

Then of course is
B1 = 20

If life came to earth with asteroids:
C1 = 20
(There was life in the solar system.)
If life was 'planted' by extraterrestrials on Earth, C1 may be 0.

So my other answers might be:
A2 = 20
B2 = 19
C2 = 5

A3 = 20
B3 = 18
C3 = 2

A4 = 12
B4 = 5

A5 = 10
B5 = 2
C5 = 2

(I hope my answer is not too 'acnostic'. If so, delete it.)

Wow! Thanks for the interest. Is fascinating to see what people think in this matter and how these possibilities relate to each other by our criteria.

C3 = B5.  If extraterrestrial intelligence has visited the solar system at any time in its history, I think it very likely would have visited Earth.  This also means that I don't think intelligence arose in the solar system but off of Earth.

20-A1 < C5-0.  I find it less likely that we are the first life to exist in the universe than that we are currently being visited by an extraterrestrial intelligence.  However, I still find the latter pretty unlikely.

Love this kind of insight on the topic (coming obviously from Watsisname). Indeed, I've shown 3 inescapable logical constraints that any set of answers must obey but I haven't mentioned any further reasonable constraints (also to make as little influence as possible).

Since you are all open about what you think I might add my own answer soon (adding comments similar to yours about how I think the odds relate between them).

Destrucules from Discord gave these

Thank you so much Doc. I've just created a discord account just to keep track of these. I know a lot of SE things are been debated there so it was just a matter of time

According to my information, the actual origin of life is an absolutely unique, absolutely improbable process that cannot possibly happen a second time in the universe.
But we know that there is life. So the question is, did life originate on earth?
If life originated on Earth, then is the answer:
A1 = 0

But if it originated somewhere else in the universe, and came to earth with asteroids, for example, then the answer is of course:
A1 = 20

That's also some interesting perspective I wouldn't have thought about (the placement of a switch-like barrier between non-life and life in such proportions).

Mmm I can do one of these things (you decide which one I do):

• Choose the second option (since it is the more complete and thought set of answers)
• Choose to do a mean between the two options (between all scores are zeros and the second set of answers) which is just your second set of answers divided by 2 in this case.
• Choose to do a weighted mean between the two options (just tell me what probability you assing to the first and second set of answers happening in reality). If you think there is 50% chance of all being zeros and 50% chance of the other set of answers been realistic then we are dealing with a simple mean, but if the odds are different just say it and I will use this method for your case.
• Ask you if you can choose and rethink a new set of values and only one. Which is the most coherent way to act here if I want "the law" to be applied the same everywhere and not have two answers at the same time or half an answer.

I really think that life is so unlikely that it actually only happened once in the universe.
(Unless a hitherto unknown mechanism is discovered that makes life creation much easier than expected.)

So it's really a question of whether life originated on earth or came to earth through panspermy.
The question now is, how likely do I think life came to earth through panspermy.
It's very likely less than 50%, but I actually have no clues at all for a rating.
So I can only say 50%.

So you can just divide all my values in the second answer set by 2.

I'm copying Wats' reply substituting with my own answers (numbers rounded down).

A1 19  There is/has been ETL in uni
B1 17  There is/has been ETL in MW
C1 3  There is/has been ETL in SS

A2 18  There is/has been complex ETL in uni
B2 16  There is/has been complex ETL in MW
C2 2  There is/has been complex ETL in SS

A3 18  There is/has been ETI in uni
B3 5 There is/has been ETI in MW
C3 0  There is/has been ETI in SS

A4 1  There are current ETI comms in MW
B4 0  There have been ETI comms attempted with us

A5 1  There is physical contact between ETI's in MW
B5 0  There was physical contact between ETI and Earth in past
C5 0  There is currently ETI on Earth

Notes: I think it's pretty likely that the SS is and has been completely dead outside Earth (excluding any meteoroid passengers unable to settle on new planets or moons).  Simple life is therefore very rare, but the size of the universe or even the MW makes it very likely.  It's very rare for simple life to evolve to complex life, but the size of the universe makes it likely, even in the MW.  It's very rare for complex life to evolve into intelligent life, but the size of the universe makes it likely, though not in the MW.  One thing somewhat missing in these questions is the distinction between surface life and ocean/subterrestial life.  I think the odds for surface life to evolve into something complex or intelligent is vastly less likely.  So there might be much intelligence out there, but complex science and space exploration would be extremely difficult for them and space travel next to impossible.

The history of Earth's history may act as a rough guide to the probabilities, when looking at the time needed for simple life to evolve into complex life, and complex life to evolve into intelligent life.  It may be more likely that intelligent life evolves from complex life, than complex life to evolve from simple life, considering that if a planet got as far as getting complex life, conditions have been fairly stable and the probability that stability will continue is high.  We currently have little data to judge whether simple life is likely to form, but exploration of the SS will give us some ideas.

A1) 20
B1) 18
C1) 9

A2) 20
B2) 14
C2) 5

A3) 15
B3) 8
C3) 0

A4) 3
B4) 2

A5) 1
B5) 0
C5) 0

Since there are many planets in the Milky Way, I've put similar values to Universe/Milky Way rate. Of course I know that the Milky Way has a waay lower number of planets than the whole universe. I give a lot of importance to the "has been" because there is a lot of time between the first stars with high metallicity and now. 

It seems that just like JackDole and midtskogen I'm quite pessimistic.

A1 19  There is/has been ETL in uni
B1 18  There is/has been ETL in MW
C1 13 There is/has been ETL in SS

A2 4  There is/has been complex ETL in uni
B2 3  There is/has been complex ETL in MW
C2 1  There is/has been complex ETL in SS

A3 3  There is/has been ETI in uni
B3 2 There is/has been ETI in MW
C3 0  There is/has been ETI in SS

A4 1  There are current ETI comms in MW
B4 0  There have been ETI comms attempted with us

A5 0  There is physical contact between ETI's in MW
B5 0  There was physical contact between ETI and Earth in past
C5 0  There is currently ETI on Earth

I might be to much interested in the Rare Earth Hypothesis lately; the idea that the universe might be an ocean filled with extraterrestrial microbial lifeforms but a dessert for complex multicellular organisms. I think we will even found life in our own Solar System in a few generations, but "animals", "plants" and "fungi" seem to me to have happened in our planet due to very specific circumstances that have been just as unique as the emergence of complex life in Earth's history (thus meaning there is not a case in favor of evolutionary convergence towards complex organisms, which IMO makes a lot of sense considering the degree of adaptation that simple life forms can reach). The idea that the boundary between simple life and non-life is more diffuse and less of a leap than the one between simple life and complex life is really very suggestive to me. I think intelligence is not such a great leap either relative to complex life considering the timespan of its developement since the Cambrian Explosion, the fact that there have been a few different intelligent species in our planet and my absolute trust in the mechanics of natural selection to reach huge amounts of complexity once the initial barriers have been surpassed (like, maybe the simple to complex life barrier). So my optimism for ET life in general is large, not so for complex life, and I'm very optimistic about intelligent life just if complex life is reached. The idea of intelligent life communicating between the stars sounds almost ridiculous to me, I still can't realize how inmense how vast the crazy abyss between stars is and at the same time I think that 13.8 billion years of history is not enought time for stars to produce enought complex chemical environments, allow for enought time for evolution to reach intelligence and also make these intelligent creatures visit each other in time, much less Earth, this insignificant corner, and much more less likely in our lifetimes. But surely this is just an opinion and what I really think is that we have no clue at all, just guesses and perspectives influenced by folklore and pop culture (which is the real revelation we can get from the answers of this poll).

Now that I have >20 answers I start thinking about how to best graphically display the results when it reaches more than 100 people Stay tuned!

Yes, once there is a Cambrian Explosion event, I think social life is very likely, i.e. animals that communicate and socialise, perhaps almost unavoidable.  Since a CE event is rare and requires much time, conditions for further evolution are likely stable.  Animals that become capable of exploring the entire universe might be more a fluke, but not extremely unlikely either.  Besides being intellectually capable humans are also lucky being land creatures, and in the eyes (or similar) of other intelligence trapped in fluid, being practically space-born creatures.

If questions contained the word "will be" I think I would give a 20 everywhere except the lasts two or three.

I dont think it's possible to even guess one way or the other.  But I will try anyway   One thing, we're talking about life as we know it, and it's easily possible there are exotic forms of life not even based on carbon and maybe even life that exists in interstellar space.  Life can exist in space, lichen has been found on the outside of the ISS!  But how would we even know exotic life was alive from this extreme distance?  We wouldn't.  It could just be a hive of dust in the middle of space.  Also it's quite possible that technological life becomes self destructive and that's almost unavoidable unless the species colonizes space and since that is so hard to do, that sentient life goes extinct before that happens, and we may be going down that road ourselves.....

At any rate microbial life should be fairly common and if we can find that on even just one other body in the solar system that would prove that.  Multicellular life too (just look at how many times our planet has recovered from mass extinction events.)  It isn't that difficult to create life (it's nothing magical and just a series of biochemical reactions) and it could randomly start anywhere, it may even be inevitable.  The thing I have doubts about is the long term viability of technological life....they do bad things to the planet and the only real answer to that is a space-faring civilization.  I believe that we are a ticking time bomb unless we do that ourselves and not being able to colonize space because of the vast distances involved and not being able to harness the necessary energy to make it happen might have caused the demise of most other sentient species.