Skip to the tables at the end if you only want to see summary statistics.
1. What is the probability that "intelligent" life (i.e.- capable of language) exists on other planets?
My guess: 99.999%
I find it extremely difficult to believe that this one pale blue dot, this spec of space dust, orbiting an average star in an average galaxy is somehow unique in harboring "intelligent" (I use quotations because I despise the word) life. We do not know how hard it was for life to originate, or how hard it was for life to evolve from "primitive" to "intelligent" (see: you really should read this) -- we do not even have a working definition of what separates life from non-life -- but with as many trials as have occurred over billions of years and septillions of locations, even under the most conservative assumptions, it seems an absurd claim that intelligent life exists only on Earth. One study, for example, estimates that there are are at least 361 intelligent civilizations and possibly as many as 38,000 just in our galaxy -- one of hundreds of billions.
I am in the NG/YE category, but I do not think my guess would change even if I became a creationist. Why would God pick one random spec of space dust -- a spec of dust not unlike many other specs of dusts -- populate it with life, and stop there? This is why I am so puzzled by the size of the difference in guesses between groups.
My friend Harrison, a creationist, gave these reasons for his disbelief:
Statistically it seems unlikely, there is little/no actual evidence, and admittedly it doesn't really fit in with a divine spark I think is needed for creation.
It is worth remembering that, when viewed from one of our planetary neighbors, there is no visible evidence of life on Earth. In astronomical terms, just a tiny step away from Earth and all evidence of our existence disappears.
The only thing that gives me just a hint of doubt is the idea that if there are so many intelligent civilizations out there -- presumably many of them more advanced than ours -- why haven't any of them found and contacted us? (More discussion under question 4.)
2. What is the probability that any life (e.g., microbial life) exists on other planets?
3 out of the 4 YG/NE people believe any life on other planets is more likely than intelligent life. That is a perfectly rational claim for those who believe in evolution, but can someone who does not believe in evolution please explain this logic to me? E.g., do you believe "primitive" forms of life, unlike humans, just emerge without God's doing? Or do you believe that God is more likely to populate other planets with microbial life rather than intelligent life? Or are you just allowing for the possibility that your worldview is wrong, and that evolution might be right?
3. Given that life exists on other planets, what is the probability that all life has the same DNA/RNA celluar structure that we see in life on Earth?
My guess: 5%
I think this is a very interesting question, and it was the hardest for me to answer. There is actually a field of study -- astrobiology -- which focuses on this very question. I know nothing about it; it is just my gut feeling that the specific nucleic acid coding sequence we see in life on Earth is not a necessary condition for life in the Universe.
4. Given that intelligent life exists on other planets, what is the probability that at least some civilizations are aware of life on Earth?
This is also a tough one because it requires you to estimate what is possible that we have not yet discovered. On the one hand, it seems unlikely any alien civilization would have discovered us if they were using our same method -- blindly pointing satellites to the sky and hoping to intercept a radio signal -- because (1) it's statistically unlikely they would point their satellites in exactly the right place to find us, and, more importantly, (2) our radio signals have not had enough time to reach very far into space (see: universe in perspective video).
On the other hand, maybe alien civilizations have developed techniques of identifying life on other planets like we have in identifying the chemical composition of other planets. Or maybe they have optical technology that we did not know was possible, allowing them to see into our living rooms (creepy thought). Or maybe they have discovered wormholes, etc. etc. I can come up with all kinds of scenarios that sound crazy, but even less likely (and just a bit arrogant) would be the belief that alien civilizations are limited to our level of technology.
In conclusion, my guess: 95%.
Although I believe it is likely that at least some alien civilizations know life exists on Earth, I believe it is unlikely they know much about us or have tried to contact us, because presumably if they have found us, they have also found multitudes of other civilizations, so discovering life here was no big whoop-de-doo, just another instance of life in one corner of one arm of one galaxy.
I would be interested to hear why other people guessed lower probabilities than mine. Is it just the then why haven't they contacted us question?
5. Given that intelligent life exists on other planets, what is the probability most civilizations have their own version of the Bible (not necessarily centered around the same God)?
My guess: 97%
6. Given that intelligent life exists on other planets, what is the probability that at least some members of most civilizations believe in the God of Abraham (i.e., the God of the Jewish, Christian, and Muslim faiths)?
My guess: 2%
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And finally, summary statistics:
Just as a reminder: NG/YE = No God / Yes Evolution.
