10^24 stars in the Universe.

~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?

But the probability of life arising is an unknown. Intuitively I too feel it probably isn't that small, but it wouldn't be the first time intuition about the universe is wrong. How do you _know_ the odds of life arising aren't 1/10^30?

We don’t know, but we can guess that it is lower than that, and have no reason to think it is that rare.

The elements of life have been found to arise spontaneously, see Bartel and Szostak for example.

The elements of life (by this I presume you mean various small biomolecules like amino acids) arising easily doesn't imply life arises easily.

We know the probability of life arising in the universe is >0 because we exist.

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.

> 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?

I keep my religious beliefs and scientific beliefs mostly segregated, so they don't affect each other too strongly for the most part. The reason for this is that those 2 things are reinforced by different sources. My religious beliefs are reinforced by spiritual experiences (such as repeatedly being stumped by [challenging life/work problem], praying for help, and then getting distinct thoughts or impressions that miraculously unblock me... or sometimes I'm miraculously unblocked through the actions other people), my scientific beliefs are formed and are refined by reading scientific literature + critical thinking. If the 2 are in conflict (which is pretty rare), it's usually my religious beliefs that adapt to new scientific understanding. For example, if evolution seems to be in conflict with intelligent design, I reconcile by concluding evolution itself may have been the thing that was intelligently designed (i.e. "this computer program can't have been intelligently designed, we've proven it was created by an LLM" --> "ok, then the LLM was intelligently designed").

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 reconcile by concluding evolution itself may have been the thing that was intelligently designed

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.

That’s not my view, but if seeded I’d expect to find it in many more places, why would our creators only seed one planet?

> I’d expect to find it in many more places

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

Well, however improbable it is to be the first, someone always has to be.

We have no evidence we’re the first. Given the distances involved it is unlikely we’ll find other life, unless it is very common.

We have no evidence we're not the first.

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.

If I distribute standard, fair 6 sided dice to 10,000 people, and have them all roll their die in secret, would you be agnostic as to whether a 6 was rolled by at least two people?

Now distribute 10,000 sided dice to 6 people, which will be an example just as relevant.

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)

In this analogy the unknown is the number of sides on the dice (probability of life), we know there are an astonishingly large number of stars and planets that life could evolve on, so a very large number of throws, we just don’t know how hard it is for life to emerge.

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.

Yes, and if the probability of life turns out to be even more astonishingly small number, you may very well end up with six 10,000-sided dice :)

My intuition tells me it's not like that, but it's nothing but intuition.

10,000 sided dice over 10^25 throws has a high probability of success for any given no.

But you've got six throws there.

It's the proportion that matters, not absolute numbers.

The dice weren't supposed to be a parallel to the odds of other life in the universe, but just about finding if you had any limits to your agnosticism.

The dice example is one where we can readily compute the probabilities.

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.

You didn't actually give an argument. Blustery personal attack is not an argument; indeed, it's a sign you realize you don't have an argument.

The no of stars in the universe is a personal attack? Or are you upset I consider Earth insignificant?

No, it was this question:

"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.

The numbers involved here make the chances that we are unique vanishingly small IMO; the numbers are the justification.

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.

> The numbers involved here make the chances that we are unique vanishingly small IMO; the numbers are the justification.

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).

So we have:

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...

> but seems highly unlikely

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?

Universe really big, earth not so so so special

Assuming the conclusion like that is not a valid argument.

You're mistaken. Life thrives in a huge variety of environments and survives in many more, and we have evidence of similar suns and the existence of planets in habitable zones. We can observe varieties of axial tilt and configurations of moons in our own solar system. We can form (bad) estimates of probability for earth-like cosmic conditions, and they're good enough that we've found some planets where we expect they might be.

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'.

Your first paragraph there is about how life spreads around on a planet once it's arisen. It doesn't have anything to do with the chance of life arising in the first place. We have evidence of precisely one origin of life event -- all life on Earth looks to derive from a common ancestor (called "LUCA").

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's not assuming the conclusion. It's stating a fact that the universe is really big, and there's no kind of indication that the earth is particularly special.

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.

The assumption is in the "not so special" characterization of Earth.

"Just seems reasonable" isn't an argument.

Of course it is an assumption, but it seems to be a reasonable assumption unless there is specific evidence to the contrary. Much of our understanding of the universe is based on the assumption that we don't occupy a particularly special place in it.

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.

Now you are elevating life is common to a default position, simply by declaring it so. I disagree. Me, the complexity of the simplest living thing makes the default assumption that OoL is incredibly unlikely.

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.

Fallacious. Size does not determine significance.

When did anyone argue that?

Out of the dozens of planets in the universe, Earth is not likely to be so unique that it is the only place where life has arisen.

Dozens? Don't you mean, probably hundreds of trillions in the observable universe? Not that the number of planets really implies anything when we don't know the probability of life arising on one of them.

No. I meant dozens. Hundreds of trillions is dozens

I don't doubt that you intended this meaning but doesn't that seem unnecessarily ambiguous to you? Usually when people say "dozens" they mean some small handful of dozens with an absolute number probably smaller than 200 (otherwise most would say "hundreds"). Few people are going to think "hundreds of trillions" when someone says "dozens". If one is expected to think "hundreds of trillions" in this case, it seems they should be equally expected to think "hundreds of quadrillions" which would be incorrect here.

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".

I had no idea if the number of planets was estimated to be in billions or trillions and I wasn't going to look it up. So I went with dozens.

This statement doesn't seem to follow from anything. Why is Earth "not likely to be so unique"?

Your comment is not worth replying to.

https://www.space.com/30172-six-most-earth-like-alien-planet...

It's weird you think that link settles things. A planet could be Earth-like without having life. We don't know how likely life is to arise on an Earth-like planet. In particular, we cannot conclude that because we are here, the probability of it happening on Earth was high, due to observer selection bias.

https://www.fhi.ox.ac.uk/wp-content/uploads/W6-Observer-sele...