16 Aug '12 11:53>3 edits
I am making the argument here that we can deduce that it is improbable of us finding intelligent alien life ( but cannot deduce the probability of unintelligent alien life being found ) within the next, say, one billion years.
This is how:
The universe is almost 14 billion years old.
The very first planets formed in a little less than a billion years after the big bang but the first ones would have been too gaseous for it to be likely for life to formed on them. Lets make a guess here that the first planets to form in significant numbers and with conditions suitable for life formation and subsequent evolution did no occur until about ~10 billion years ago; a reasonable guess I think.
Now; life on earth started about ~3.7 billion years ago and, since earth life is the only example of life we know of that started and then evolved into intelligent life, we should make the educated guess that typically it takes very roughly about ~4 billion years to go from abiogenesis to intelligent life.
OK, so there is nothing obvious that could have stopped alien life forming ~10 billion years ago and then evolving into intelligent life ~4 billion years after that.
Therefore, there is no obvious reason to think that it would be unlikely that, if there IS intelligent alien life in our universe, at least some intelligent alien life existed about
10 – 4 = 6 billion years ago.
In fact, I would say we could deduce that IF there is intelligent alien life in our universe ( a big IF ) then there was probably also intelligent alien life in our universe 6 billion years ago.
But if there was alien life 6 billion years ago, then at least some of those species would have had the culture of keep exploring and spreading and multiplying and space-travel and colonising new planets. If, say, such an alien species found our planet, say, a billion years ago, they would have completely colonised our planet and we would not be here because they would still dominate this planet and also we would probably not had a chance to evolve into existence!
We can now deduce certain probabilities from this. For example, if such an intelligent space travelling alien species existed within our galaxy, these intelligent space travelling aliens would have almost inevitably found earth and colonised and dominated it millions if not billions of years ago and thus we would not be here. So we can deduce from this that it is extremely unlikely that there is intelligent alien species within our galaxy.
A similar argument can be used to deduce that it is unlikely that there are intelligent space travelling aliens less than ~10 million light years from our own and that would include the Andromeda galaxy.
But to apply this line of reasoning for assessing the chances of intelligent life more than ~10 million light years from us, we must consider the effect of whether some kind of faster-than-light or 'warp drive' is possible:
Firstly, IF faster-than-light travel IS possible AND if there exists intelligent space travelling aliens then surely at least one such species would have multiplied and spread throughout the universe by now because, after all, they would have existed for ~6 billion years which is more than enough time for them to work out how do do that. But, if that is the case, then they would have surely found and colonised and dominated our planet billions of years ago and we would then not be here.
Therefore, we can deduce two things from this:
1, IF faster-than-light travel IS possible then it is unlikely that there are any intelligent aliens in our universe and we are alone. So even if we achieve faster-than-light travel, we would almost certainly not ever find intelligent aliens.
2, IF there are any intelligent aliens in our universe then it is very unlikely that faster-than-light travel is possible and it is very unlikely that there are any intelligent aliens within, say, a ~10 million light year radius from us. So even if we space travelled to the maximum extent and speed possible which would probably be only a small fraction of c, we would be unlikely to find any intelligent life within, say, the next billion years.
-either way, we can deduce that it is improbable that we would or could find intelligent alien life within the next billion years.
Of course, this tells us nothing about the probability of us finding unintelligent alien life within the next billion years such as alien microbes because, for all we know, all alien life is just microbial and us intelligent life is extremely atypical and freakish.
This is how:
The universe is almost 14 billion years old.
The very first planets formed in a little less than a billion years after the big bang but the first ones would have been too gaseous for it to be likely for life to formed on them. Lets make a guess here that the first planets to form in significant numbers and with conditions suitable for life formation and subsequent evolution did no occur until about ~10 billion years ago; a reasonable guess I think.
Now; life on earth started about ~3.7 billion years ago and, since earth life is the only example of life we know of that started and then evolved into intelligent life, we should make the educated guess that typically it takes very roughly about ~4 billion years to go from abiogenesis to intelligent life.
OK, so there is nothing obvious that could have stopped alien life forming ~10 billion years ago and then evolving into intelligent life ~4 billion years after that.
Therefore, there is no obvious reason to think that it would be unlikely that, if there IS intelligent alien life in our universe, at least some intelligent alien life existed about
10 – 4 = 6 billion years ago.
In fact, I would say we could deduce that IF there is intelligent alien life in our universe ( a big IF ) then there was probably also intelligent alien life in our universe 6 billion years ago.
But if there was alien life 6 billion years ago, then at least some of those species would have had the culture of keep exploring and spreading and multiplying and space-travel and colonising new planets. If, say, such an alien species found our planet, say, a billion years ago, they would have completely colonised our planet and we would not be here because they would still dominate this planet and also we would probably not had a chance to evolve into existence!
We can now deduce certain probabilities from this. For example, if such an intelligent space travelling alien species existed within our galaxy, these intelligent space travelling aliens would have almost inevitably found earth and colonised and dominated it millions if not billions of years ago and thus we would not be here. So we can deduce from this that it is extremely unlikely that there is intelligent alien species within our galaxy.
A similar argument can be used to deduce that it is unlikely that there are intelligent space travelling aliens less than ~10 million light years from our own and that would include the Andromeda galaxy.
But to apply this line of reasoning for assessing the chances of intelligent life more than ~10 million light years from us, we must consider the effect of whether some kind of faster-than-light or 'warp drive' is possible:
Firstly, IF faster-than-light travel IS possible AND if there exists intelligent space travelling aliens then surely at least one such species would have multiplied and spread throughout the universe by now because, after all, they would have existed for ~6 billion years which is more than enough time for them to work out how do do that. But, if that is the case, then they would have surely found and colonised and dominated our planet billions of years ago and we would then not be here.
Therefore, we can deduce two things from this:
1, IF faster-than-light travel IS possible then it is unlikely that there are any intelligent aliens in our universe and we are alone. So even if we achieve faster-than-light travel, we would almost certainly not ever find intelligent aliens.
2, IF there are any intelligent aliens in our universe then it is very unlikely that faster-than-light travel is possible and it is very unlikely that there are any intelligent aliens within, say, a ~10 million light year radius from us. So even if we space travelled to the maximum extent and speed possible which would probably be only a small fraction of c, we would be unlikely to find any intelligent life within, say, the next billion years.
-either way, we can deduce that it is improbable that we would or could find intelligent alien life within the next billion years.
Of course, this tells us nothing about the probability of us finding unintelligent alien life within the next billion years such as alien microbes because, for all we know, all alien life is just microbial and us intelligent life is extremely atypical and freakish.