I gotta go with Dio on this one. Life vs. Non-life is the question, intelligence has nothing to do with it. You’re the only one who keeps interjecting all the chazerai about our being intelligent enough to observe and discuss this.
That’s right, and I have asked him to do this and he has not been able to.
No, he needs to be able to be able to establish that this was the precise path taken for life to arise on Earth, or establish that it is a precise path by which life could arise, in order for it to have any bearing on the discussion.
Plausibility is not the same as probable you know.
No, the correct reply is the one I gave. When someone claims that they have given an argument that provides a probabilty of something happening, the correct reply is ask what that probability is and how they calculated it.
How does Voyager’s vague handwaving about viruses and self-replication go any way to establish is that the odds of life arising on an earth-like planet* are somewhere north of 1 x 10-9?
Viruses arose long afterlife arose and are obligate pathogens upon it. As such they tell us less about theorigins of life than do duck billed platypuses. Vague references to self-replication tell us absolutely nothing at all.
Dodge.
Yet again.
People place bets all the time.
You have two choices:
-
No life in the universe except for earth
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Life on a planet other than the earth
Simple really and a reasonable question. I am asking for your opinion. No bullshit about, “It is unknowable!” A dice roll in Vegas is unknowable too…people still bet on it.
The hypothetical did not demand you know the odds. It is an all or nothing deal. Double your money or lose everything. You have to decide for yourself based on what you know to answer.
Take your best shot and support your decision.
I have asked you this numerous times. You have evaded every time.
Put up or admit you got nothing.
The problem with your argument rests here, in your use of “never”. The assumption on your part that scientists can only use the existence of life on Earth as their source of information.
Scientists can use other means to examine the likelihood of various simple chemicals turning into the more complex chemicals necessary for life. They can also determine the steps that would be necessary for simple life to be created, and estimate the chances of that happening under natural conditions.
Life is not some magical thing that just appeared on Earth, it is the result of a chemical process. If we understand the process, we can make a educated guess as to the likelihood of that process occurring naturally.
Same problem though isn’t it?
Protolife is just a chemical reaction. If the reagents exist then it will be generated in less than a few thousand years. If it takes longer than that then, pretty much by definition, the conditions for life don’t exist, right? I mean, if we say the conditions exist for a reaction to occur those conditions need to actually be present, not just potentially present or eventually present in a few eons.
So if the conditions for life exist, it will be generated within few thousand years, by definition. The only other variable is the time from protolife to robust life. Many variations will presumably evolve far to slowly to become robust life within 50 million years and those strains will become extinct. So we are only left with those strains that produce life within 50 million years.
I think I kind of get your point. You are assuming that a planet can have suitable conditions for life yet not generate protolife for a prolonged period. But can you explain how this might be possible? If the reagents exist and are in contact shouldn’t the reaction start within a few millenia at the very most? And if the reagents don’t exist, or they aren’t able to come into contact, then can we still reasonably argue that conditions are suitable for life?
Maybe it will help if I put it another way. If Earth were to remain grossly the same as it was 4 billion years ago, same gross atmosphere, temperature, crust chemistry etc., how could the reactions leading to protolife be *delayed *for more than a few millennia?
I can see that if it required seeding from a nebula, for example, this need not happen immediately after the planet has cooled from the last asteroid collision, but if such *extrinsic *requirements are built in then the ability to calculate probability of life evolving becomes even more impossible. Maybe such seeding *must *happen soon after catastophe or the seeds can’t survive. On any planets seeded billions of years after a catastrophe the conditions wouldn’t let life arise. Once again the fact that t1 is short can be evidence for or against life being highly improbable. That damn anthropic principle in play again. The fact that life exists here proves that the conditions for life existing here must have occurred. Any evidence about the whens and wherefores can’t tell us a damn thing because the facts that point to high probability can also point to the need for low probability.
I remembered the name of the principle I alluded to in the previous thread; the Principle of Mediocrity.
This is the principle that we should assume that the Earth is “nothing special”, partly because the human tendancy is to do the opposite.
Note however that it does not mean declaring that one knows there are lots of Earthlike planets out there. It just means we start from a position of assuming that Earth isn’t special.
Ahh, no.
If you follow the discussion Saganist and I are having, you will see that the presence of intelligent life is in fact a core issue.
To help you understand this, I ask you to imagine what your thoughts might be if the probability of life arising in the universe were zero.
If your answer was “I wouldn’t have any thoughts, I wouldn’t exist”, then congratulations, and you are beginning to understand why intelligent life is crucial to the discussion.
I also suggest you read the Wikipedia page on the Anthropic Principle. I linked to it in the original thread.
Right, and? So they can examine the likelihood of reactions occurring. Yep, been there, done that. This morning in fact.
Now how does this allow any calculation of the probability of life arising? Given that in any journal there will be articles championing extraterrestrial origins of life, clay theories, RNA theories, AA theories, micropore theories. With all that diversity of theories, most of them mutually contradictory, how does calculating rate equations go any way at all to calculating the probability of life arising?
Start with something simple. If life arose from intergalactic proteins that propagated in freshwater micropores, then can you explain how precisely calculating the rate reactions of RNA self-replication bring you any closer to determining the probability of life arising?
And… this is how you go about making an educated guess about something you are unable to directly observe.
If you understand the steps required for the formation of new life, and understand the relative likelihood of each of those steps occurring naturally, you have information that can help you to narrow down your probability range.
I mostly agree with you, Blake. And I have used the argument too that a random hit doesn’t say anything at all about the one being hit apart from being there in the first place.
But I want to point out that the 50 million year span you mentioned is also a statistical number not a target date; a planet might have double the time or more before it is hit by a catastrophe or far less. Though I don’t see how this changes anything: We still don’t know the likelihood of life to form or the “universal rules” for robust life to evolve from it. It might happen all around us or not at all.
Which we don’t have, in any way at all. So once again I ask, what is the relevance of the examples you gave.
We don’t understand where life arose. We don’t understand how it arose. We don’t understand what condition are necessary for it to arise. We don’t understand what form it took when it did arise.
Those are just the major unknown factors. We have multiple, equally compelling, competing, mutually contradictory theories for all of those things.
So since we clearly don’t understand the steps required for the formation of new life, how did you go from that state of ignorance to calculating the probabilities involved in it arising?
I can’t remember the figure that Miller uses, IIRC it was something like 10 million years for all seawater to pass through hydrothermal vents and be sterilised. It’s not quite as random as it might seem.
Sure, the processes that take place in certain environments follow rules, they won’t be random; but that doesn’t mean we neccesarily need this exact environment to produce life. But to beat you to the punch: the one place that we do know where life exists, is indeed subject to conditions that define the window of opportunity for life to evolve and get a hold far beyond statistical randomness. Any other conditions are fictional.
You said in your OP that "We can never know what that is, or even make an educated guess "
Are you saying that we can never understand where or how or what conditions are necessary for life to arise?
Never is a long time, so no, not necessarily never.
At this moment we can certainly not understand where or how or what conditions are necessary for life to arise. If we did understand that there wouldn’t be at least three competing, equally valid and mutually contradictory theories on each topic, would there?
The “never” in the OP was meant to refer to things as they are now. I concede that it’s ambiguous and I should have been clearer. We can never know how likely life is to arise on any given planet *using the information we currently have * because the only sample we have must have had life evolve on it.
In the future we may be able to increase that sample size to include other planets with life on them, at which stage we can possibly start to establish some probabilities. In future we may be able to obtain enough evidence to make an educated guess abiogenesis on Earth. But as things stand we can’t do those things.
The simple fact is that your argument works both ways. While we have no real idea of the probability that life occurs elsewhere that doesn’t make it any more reasonable to assume that it’s vanishingly unlikely. What we have is a set of facts:
- Life has been proven to have arisen once
- Life didn’t take that long to get going on earth
- The universe is really fucking big
- There is nothing particularly unlikely looking about our planet / solar system. We aren’t on some sort of freak body orbiting a black hole or anything. We appear to be just like everywhere else.
Facts 1 & 2 suggest that life is more likely than ‘1 in the number of particles in the universe’, simply by it having arisen in a relatively short time. Nobody would argue this is proof, simple a weighting of probability.
Facts 3 & 4 tells you that the conditions for life are prevalent in the universe and that no matter how slim the probability (within reasonable bounds) that life will arise it is going to occur more than once.
This doesn’t prove anything, but when you are talking about the range of probabilities that life has arisen somewhere else in history of the universe it weights it fairly heavily in favor of it having happened. Now, how strict you are about temporal coincidence changes things. If your argument is that ‘at this exact moment in time we may be the only life in the universe’ than you’d have more of a point. It’s possible that life doesn’t last very long before being obliterated.
But I don’t think that is your argument, which means your suggestion that life arises and is killed off is bizarre. If it exists to be wiped out than you have already invalidated your argument. Besides that you are simply adding another unknowable probability which could go either way.
You’re asking Blake to support either a “yes” or “no” answer when he insists the correct answer is “I don’t know”.
Why should he support a “yes” or a “no” when neither of those correctly characterizes his position? His position is “I don’t know.” That’s the position he’s supporting.
The sentence I’m thinking of in my head right now is either true or false, right? Okay. Place your bet. How much yawanna bet it’s true?
No, they don’t suggest anything of the sort.
I addressed this in the OP and numerous posts since. If you have anything new to add i will address that, but I won’t bother addressing points that I have already falsified.
Absolute nonsense.
Since you have facts that tell you that the conditions for life to arise are prevalent in the universe, you must be able to tell us what those conditions are. So go on, tell us what they are, and then I will dig out the references that ague exactly the opposite.
That is the problem you face when you make silly statements like this. We have no idea what conditions are required for life to arise. Every hypothesis has at least two competing and mutually contradictory hypotheses. With that fact in mind, please list for us the conditions that are necessary for life to arise that you the facts tell you are prevalent in the universe.
And that is just a total non sequitur. It follow from nothing at all
Good, another person who can weight the probabilities. Please do so. I look forward to seeing the calculations you used to do this weighting, particularly the figure that represents the probability of life arising on any given planet.
Since you have rehashed the same tired nonsense that I have already falsified, and made the same baseless claims that you can calculate the probabilities it seems pretty damn clear that you have either not read my argument or been unable to understand it.
I repeat: If you have anything new to add i will address that, but I won’t bother addressing points that I have already falsified.
As Blake said in the post you’re responding to, we don’t understand the steps required etc…
The fact that the Earth is the only planet we know of with life does not prevent us from studying the nature of life, and developing a sense of whether or not the Earth is unique.
The point is not that we have enough information today, but that you seem to think it’s impossible to study the topic and form a reasonable hypothesis without sampling other planets.
If the question is “does extraterrestrial life exist?” then I only need one other planet with life to answer it conclusively. Your opinion seems to be that if we haven’t actually discovered another planet with life on it, it is impossible to even guess if there is other life out there.