Did God create little green men?
Forget trying to count the number of angels on the head of a pin - there's an even more critical theological question weighing on the minds of Vatican astronomers: did God create little green men?In an interview published today in the Vatican newspaper L'Obsservatore Romano, Reverend Jose Gabriel Funes, the Vatican's chief astronomer and scientific adviser to Pope Benedict, said that there's no conflict between the Christian faith and the existence of extraterrestrials.
But the idea that there might be intelligent life beyond Earth doesn't easily fit into the Christian worldview. According to the Bible, God created Earth as the centre of the universe and men in his own image. Would the Good Book's credibility be compromised by the discovery of alien life? I can just imagine the higher-ups at the Vatican pacing nervously as SETI began searching the sky for ET signals and surveys turned up planet after planet outside the solar system - some of which might be able to host life.In a clever manoeuvre, the Vatican has pre-empted the threat an alien discovery would pose to Christianity. Now they say they won't be the least bit surprised should we make contact with our "extraterrestrial brothers". And why should they? According to Vatican astronomer Guy Consolmagno, the Bible is chock full of references to aliens. In Intelligent Life in the Universe, published by the Catholic Truth Society in 2005, Consolmagno wrote:"There are, unquestionably, nonhuman intelligent beings in the Bible. At least one group of such creatures is familiar to us all: angels. But are the 'holy ones', those 'in the sky', the 'morning stars', and 'heavenly beings' mentioned in Psalms and elsewhere references to angels? Or do they refer to some other kind of life beyond our knowledge?""If you're really eager to find a reference to extraterrestrials in the Bible," he writes, "you can't do better than John 10:14-16. 'I am the Good Shepherd . . . I have other sheep that do not belong to this fold. I must bring them also . . . so there will be one flock, one Shepherd.'" 
Other sheep? Aliens, obviously! And it sounds like they are on their way.The existence of ET life does leave Consolmagno with some head-scratchers. Are they burdened with original sin? Is there a "cosmic Adam" that predates his Earthly clone? Does one baptise an alien?When little green men finally make themselves known, the Christians will be ready for them. After all, as Consolmagno says, "Having a soul has nothing to do with how many arms or legs or tentacles you have."
Life Beyond the Solar System
One of the really historic events of the last decade is our discovery that other planetary systems exist. The question "Are there planets around other stars?" is thousands of years old, and we finally know the answer is "YES!"
I discussed this a month or two ago. And while this is a huge advance, we still don't have any idea how common planetary systems are. Do all stars have planets? Only a few? We just don't know yet.
This is relevent for our present discussion, as life as we understand it requires a planet.
The problem of timescales comes up again here. If most of the life in the Universe is single-celled organisms, we don't have any good way of finding it outside our Solar System. The only life we are likely to find is life we can communicate with. This brings us to the Search for Extra-Terrestrial Intelligence, or SETI.
One of the only relevant questions we can ask in SETI is "How likely is it that there are other civilizations in the Galaxy for us to communicate with?"
Now that the question is on the table, how do we go about answering it?
We can't answer it directly. We don't know enough. But we can at least figure out a way of asking the question that tells us what we need to try to figure out. This is typically couched in terms of something called The Drake Equation:
One of the really historic events of the last decade is our discovery that other planetary systems exist. The question "Are there planets around other stars?" is thousands of years old, and we finally know the answer is "YES!"
I discussed this a month or two ago. And while this is a huge advance, we still don't have any idea how common planetary systems are. Do all stars have planets? Only a few? We just don't know yet.
This is relevent for our present discussion, as life as we understand it requires a planet.
The problem of timescales comes up again here. If most of the life in the Universe is single-celled organisms, we don't have any good way of finding it outside our Solar System. The only life we are likely to find is life we can communicate with. This brings us to the Search for Extra-Terrestrial Intelligence, or SETI.
One of the only relevant questions we can ask in SETI is "How likely is it that there are other civilizations in the Galaxy for us to communicate with?"
Now that the question is on the table, how do we go about answering it?
We can't answer it directly. We don't know enough. But we can at least figure out a way of asking the question that tells us what we need to try to figure out. This is typically couched in terms of something called The Drake Equation:
Nc is what we're after: The number of other technologically advanced civilizations in our Galaxy, with which we could potentially communicate. What are the inputs that go into that estimate?
N*: The number of stars in the Galaxy. This is about 2x10^11 (200 Billion).
fp: The fraction of those stars with planets. We now know this isn't 0. It probably isn't any more than 0.5, because about half of all stars are in binary systems, and planets that form in binary star systems are probably tossed out of the system relatively soon (much like Jupiter tossed out Oort cloud objects.
n_lz: The number of planets in a given planetary system that are at the right distance for conditions to be favorable for life. We have no idea what this number is, really. Maybe 1-2.
f_L: The fraction of such planets on which life actually arises. This could be anywhere from 0 (life doesn't arise) to 1 (life always arises when conditions are good).
f_i: The fraction of planets with life on which that life evolves intelligence. Again, this could be anything from 0 to 1.
F_s: For those planets with intelligent life, what fraction of the lifetime of the star does the technologically advanced civilization survive? This could be as small as essentially 0 (technologically advanced civilizations destroy themselves quickly), or maybe as long as 0.5. If we survive until the Sun turns into a Red Giant, our F_s would be about 0.5. Well, if you've been keeping score, you will have noticed that we have a string of six numbers, one of which we have a good handle on (N*). One of them we are starting to be able to figure out (Fp). And the other four are total guesswork. In other words, if we make optimistic guesses, then we conclude that N_c is perhaps as large as 10 Million. And if we make pessimistic guesses, then we conclude that N_c ~ 0.
So the Drake Equation doesn't give us predictive power, so much as it gives us a structure for studying the problem. It tells us what we don't know, and what we have to try to understand, in order to make any progress.
Search for Extraterrestrial Signals
The most promising part of the spectrum to use for this is the radio regime. This is because radio waves are not absorbed by interstellar dust, so signals will make it clear across the Galaxy (given enough time).
Now, think about the implications of this for a minute. This means that there could be guys sitting in an extra-terrestrial frat house on a planet around some star 35 light years away, tuning into Gilligan's Island. Or opera fans 90 light years away listening to Enrico Caruso. We've been leaking low-power radio signals for the better part of a century.
There have been small pilot programs designed to search for such signals from other stars. But we haven't found any yet. This isn't much of a constraint though. There are LOTS of stars, and there is a lot of bandwidth (you have to tune your radio to the right station, after all).
N*: The number of stars in the Galaxy. This is about 2x10^11 (200 Billion).
fp: The fraction of those stars with planets. We now know this isn't 0. It probably isn't any more than 0.5, because about half of all stars are in binary systems, and planets that form in binary star systems are probably tossed out of the system relatively soon (much like Jupiter tossed out Oort cloud objects.
n_lz: The number of planets in a given planetary system that are at the right distance for conditions to be favorable for life. We have no idea what this number is, really. Maybe 1-2.
f_L: The fraction of such planets on which life actually arises. This could be anywhere from 0 (life doesn't arise) to 1 (life always arises when conditions are good).
f_i: The fraction of planets with life on which that life evolves intelligence. Again, this could be anything from 0 to 1.
F_s: For those planets with intelligent life, what fraction of the lifetime of the star does the technologically advanced civilization survive? This could be as small as essentially 0 (technologically advanced civilizations destroy themselves quickly), or maybe as long as 0.5. If we survive until the Sun turns into a Red Giant, our F_s would be about 0.5. Well, if you've been keeping score, you will have noticed that we have a string of six numbers, one of which we have a good handle on (N*). One of them we are starting to be able to figure out (Fp). And the other four are total guesswork. In other words, if we make optimistic guesses, then we conclude that N_c is perhaps as large as 10 Million. And if we make pessimistic guesses, then we conclude that N_c ~ 0.
So the Drake Equation doesn't give us predictive power, so much as it gives us a structure for studying the problem. It tells us what we don't know, and what we have to try to understand, in order to make any progress.
Search for Extraterrestrial Signals
The most promising part of the spectrum to use for this is the radio regime. This is because radio waves are not absorbed by interstellar dust, so signals will make it clear across the Galaxy (given enough time).
Now, think about the implications of this for a minute. This means that there could be guys sitting in an extra-terrestrial frat house on a planet around some star 35 light years away, tuning into Gilligan's Island. Or opera fans 90 light years away listening to Enrico Caruso. We've been leaking low-power radio signals for the better part of a century.
There have been small pilot programs designed to search for such signals from other stars. But we haven't found any yet. This isn't much of a constraint though. There are LOTS of stars, and there is a lot of bandwidth (you have to tune your radio to the right station, after all).
