Not necessarily. It could simply have been part of a slow process towards a certain set of conditions, such as atmospheric conditions. A slow process towards a situation where there is enough potential energy to be gathered in to make the evolution of an energy-gathering-in organism possible.
Life might have only evolved once, we have absolutely no evidence to the contrary. As to how unlikely that is, whether staggering or otherwise, we simply cannot say. The whole point being that we have no idea whatsoever what the probability of life emerging is. Personally I would imagine it's not that unlikely - we're here, after all. But with only a sample size of one, all I can say is that is it definitely possible. Whether it's 1 in X over unit time, or one in X^X over unit time, one cannot say. Just because we're here does not preclude the possibility that the probability of life emerging is spectacularly, vanishingly small. It could like rolling a dice, or it could be like winning the lottery. Until we find definitive evidence of a totally disparate emergence of life, we can only speculate on its likelihood, any assumptions are sheer guesswork.
Predictions yes, it's the unequivocality of some arguments I take exception to. Not yours so much, I'm really more venting my frustration with the way these issues are often described in popular science. I think many of the general public equate assertions such as "almost certain" as being equivalent to "certain". Which just riles me a bit. I think more time should be spent teaching probability theory in schools...!
I think it would be the greatest discovery of all time, ever, bar none!
I am very passionate about attempts to model the emergence of life, either computationally or practically. Any success in such endeavours, whilst not definitive proof that it has actually occurred elsewhere, would of course massively bolster the case for ET life. Especially if the results of such experimentation threw up other possible forms life could take, which might influence the search for biogenic effects, such how alien life might affect the atmospheric chemistry of its host world.
Assuming, of course, they ever developed into complex life in the first place. Whilst the probability of emergence of life itself is an unknown quantity, even if it does arise the progression from simple unicellular to complex multicellular life is far from assured. Most life on earth, in terms of abundance, is unicellular. Single celled life existed on earth quite happily for billions of years, and no one's entirely certain how it made the leap to multicellular life with specialised cells working together in a cooperative fashion (in one organism, as opposed to a cooperative colony model). If it happened here, it could happen elsewhere, but it's quite plausible that the majority of alien life (assuming it exists) is unicellular. If we take earth as a representative model, given the time that life spent here in a purely unicellular form, compared to the time that multicellular life has existed, it would seem quite improbable that we'd stumble upon alien life that similarly made the transition. Any advanced alien visiting earth at any time since the dawn of life here would be far more likely to arrive when there was only single celled life forms to say Hi to.
That song terrified me as a child.
But possible.
You might find it laughable, but I would consider that to be dismissive & wholly unscientific. We know that intelligent life arose at least once, but we have absolutely no idea how probable such an event is. Resorting to the argument of "it's a big universe, therefore it must be inevitable" is essentially saying that you dismiss out of hand the possibility, no matter how remote, that there is no other intelligent life. To dismiss a possibility because it appears improbable or unsatisfactory, is anything but scientific.
Here, Kimble, if that trope excites you, you should read Pohl's Gateway series. The macguffin is an asteroid with a lot of ships on it left behind by an (apparently) extinct alien race, ships that cannot be reprogrammed for new destinations, but which take human adventurers to all manner of exotic locations.
That song terrified me as a child.
Well, we don't know that...
