> statistically there is other life in the universe
Please explain the reasoning by which one reaches this conclusion.
Please explain the reasoning by which one reaches this conclusion.
~10^25 planets in the Universe.
13 billion out of a googol years elapsed.
And you think our insignificant spec of dust is the first or will be the last on which life evolved?
The elements of life have been found to arise spontaneously, see Bartel and Szostak for example.
However, we don't know if life can arise spontaneously given the right conditions (abiogenesis) or if must it be "seeded" at some level by an existing life form (i.e. deity, asteroid containing bacteria, etc)?
I'm religious, so I'm more in the "seeded" camp than "spontaneous" camp but either way, I strongly believe there is life on other planets in the universe, it's just too bad the universe is so big and light so slow that it's hard to confirm.
Hijacking someone else's comment to ask without judgement or agenda - How, if at all, would it alter your religious beliefs were life/intelligent life to be found on another planet?
One thing that would probably alter my religious beliefs significantly is if abiogenesis or synthetic life were proven possible (i.e. you can clearly show in a lab how to make life arise from non-life, or how to create artificial life). I don't find the current "primordial soup" or other abiogenesis arguments convincing enough to abandon religion, though I do re-visit the wiki every couple years to see what's new on that front.
I don't understand why I don't hear anyone else take this position. To me it's obvious and it's hard to find any other way to reconcile them. (But I'm not religious.)
Well, actually there's two quite different things that could be asserted along that line and it's not clear which you meant: either that evolution is a mechanism by which the hand of God can meddle in random occurrences to pick outcomes, or that it's completely hands-off.
But I would state the second one differently: that the universe was set up to allow evolution and all the other systems of natures to create the world today. Evolution itself is ultimately a consequence of physics and statistics.
I'd expect the same, the problem is just the vast distances involved with space (meaning we are looking into the past) and the enormous quantities planets to check make it difficult to find other life out there
I remind you that I'm not claiming we're first; I'm asking for justification for claims that life exists elsewhere, or is common, or that we're not the first. Myself, I am taking an agnostic position, not committing myself to unjustifiable conclusions.
It sure makes sense to assume we're neither alone nor first, as until we actually prove it either way that's just what the odds are - but I'm tired of people acting like this means we're definitely not the first. If you gave 10,000 people a number between 1 and 10,000 in random order, the probability that any given person got number 1 is 1/10,000, and yet the probability that someone got 1 is 1.
(though there's another problem at play: "first" may not necessarily be a well-defined term at these scales)
I agree with you the odds are strongly in favour of us not being first or unique. I didn’t say we must be first but find it very unlikely given the numbers.
My intuition tells me it's not like that, but it's nothing but intuition.
It's the proportion that matters, not absolute numbers.
The problem with origin of life is we can't do that with the information we have. It's not that the probability is high or low, it's that it's unknown.
"And you think our insignificant spec of dust is the first or will be the last on which life evolved?"
First, when I ask someone to justify their position, I expect a justification, not questions about what I do or do not believe. My beliefs have jack shit to do with any justification for others' statements.
Second, that question slips in the conclusion you're trying to justify, in the word "insignificant". If Earth were the sole lifebearing planet in the universe, it would be extremely significant. By proclaiming by fiat that it's insignificant, you've ruled that out.
I suspect what you did there was assume that IF another world has physical properties like Earth, THEN that world would also produce life as occurred on Earth. But this inference is not valid, because the process could very well have been very nondeterministic, depending on one or more very unlikely steps. There is no reason to conclude if Earth were run through its history all over again that life would again have arisen.
Those numbers mean that even if the odds of life are vanishingly small, there was and will be other life out there. We’re not talking about one world like Earth but likely billions at least. As far as we can tell our star is in no way unique or special, and if those same processes happened say 100000000000000000000000 times elsewhere, it seems very unlikely to me that they wouldn’t produce self-replicating life as well somewhere, sometime.
This is nothing but handwaving. Your argument evaporates when examined closely or critically.
> Those numbers mean that even if the odds of life are vanishingly small, there was and will be other life out there.
Obviously not. If there are N places where life could arise, but the chance that life arises at each is << 1/N, then your conclusion does not obtain. For any N, there is always a sufficiently small chance life would arise that would ruin your conclusion.
You are slipping in an assumption again, that the chance can't be "too small". But we can't rule out that some event in OoL is extremely, astronomically, exponentially unlikely. All known examples of living systems capable of Darwinian evolution have great complexity, and that initial complexity has to have come from somewhere. We can't rule out that at least some of it was just due to some extremely low probability event(s).
Unimaginably large no of plants, odds of life are rare, but life is common because of the no of planets.
Unimaginably large no of planets, odds of life are such that it only emerged once in billions of years over 10^25 planets, so odds of life emerging are something insane like 10^30:1.
Your conclusion that life is probably unique on Earth is possible, but seems highly unlikely, and in the absence of other information, I'm going to assume the most likely outcome, which is that we are not alone, we don't yet know how alone, but the outlier is to say life emerged but once.
Feel free to make whatever assumptions you like, but stating the obvious about assumptions doesn't change my argument at all or invalidate it - obviously you have to make assumptions when information is incomplete. Nobody is saying with certainty there is or is not life (clearly we don't yet know), we're talking about the most likely outcome given what we know.
We have found the building blocks of life on asteroids already, if we do find extra-terrestrial life in our neighbourhood it would mean life is extremely common in the universe due to the no of planets and time, if not, it doesn't mean much, it just means it is not extremely common, the outcome you posit is way on the other extreme of the scale.
https://eos.org/articles/lifes-building-blocks-found-in-benn...
How is this judgment reached? What's the probability distribution assumed for the probability of life arising, and how was that estimated?
This is nothing more than a personal feeling on your part dressed up to try to make it seem to be something that isn't completely subjective.
This whole subject, touching as it does on existential questions, is rife with opportunities for bias, so it's very important to be rigorous and explicit in reasoning, not resort to "feelings", or in arguments that end being exercises in rationalization of those feelings.
What one must do in such a situation is seriously question ones own assertions. "How do I know that this is true?" "What would look different if this weren't true?" So many seem to just voice their intuition and stop thinking.
I want you to imagine an alternative world, let's call it Schmearth. It's inhabited by Schmumans, orbited by the Schmoon. It's in a universe much like ours, but the laws of physics are such that OoL has a very difficult step, so Schmearth is the only life bearing planet in their universe. My question to you: what would be different that they would see that we do not (or vice versa)? If you can't identify such a thing, how do we know we aren't ourselves living on Schmearth?
Even if one agrees that "dozens" is accurate to mean "hundreds of trillions" it still misses the mark for the argument because the odds come from the high number of planets. That is to say, there are very low odds that any individual planet harbors life but ostensibly much greater odds that one planet in a set of planets harbors life. Saying "hundreds of trillions" gets that point across better than "dozens".
https://www.space.com/30172-six-most-earth-like-alien-planet...
https://www.fhi.ox.ac.uk/wp-content/uploads/W6-Observer-sele...
It seems like a far larger assumption to think Earth is unique in the cosmos, given nature's tendency to repeat itself. There are numerous natural harbors on earth, for example - places where the sea currents and land terrain combine to make a relatively calm environment even during stormy conditions. If we view Earth and the solar system as a natural harbor in space, what basis is there for thinking it can not exist anywhere else? The fact that we're uncertain about exactly how common it is is not a good reason to think the answer is 'not at all'.
We don't know how common OoL is on a planet like Earth. We cannot use the fact it occurred here to conclude it's likely, since if it didn't occur here, we wouldn't be here. Our mere presence to ask the question biases the observation. The less likely it was, the more biased the observation.
Second paragraph: what is this supposed tendency of nature not to repeat itself? The universe is full of objects that are unique arrangements of atoms, not repeated anywhere else. Indeed, all but extremely small objects are very likely to not recur. So this supposed universal property of repetition doesn't appear very universal. Proposing that Origin of Life is in the subset of phenomena that do repeat is just begging the question.
As for "what basis is there for thinking it can not exist anywhere else?", that question is relevant only if I were asking you to believe life is not common, not if I were asking for justification of statements that it is common. The opposite of belief in X is not belief in (not X)!
It also just seems reasonable that, given the size of the universe, the odds of life forming exactly once seems much less likely than the odds of life forming more than once.
"Just seems reasonable" isn't an argument.
I've heard theories about either the presence of Jupiter, or something about the nature of our moon as providing a safe long term environment for life to form on earth, but even that doesn't feel that special, when there are 10^21 stars with planets in the universe.
You should be aware that the logic you are using, vulgar Copernicanism, was used in the 1700s to conclude that the other planets in our solar system must not only have life, but intelligent life!
What your argument ignores is that we don't live on a randomly selected planet in the universe. We necessarily live on a planet that has life. This "observer selection bias" has to be taken into account; the rarer life is, the more biased our local observations will be.