RIP Allan SandageFollow

Nor have you made any sort of convincing argument so I'm cool with that.

Likewise.

Heh.

Also, +1

Uhh, you'll have to correct me if I'm wrong, but in the cases of macroevolution that have been observed, it's been entirely debatable if these were changes that were "permissible" within the existing genetic structure. i.e., yes, we have observed macroevolution (technically), but the evidence for macroevolution of anything other than a very closely related species (a genus, family, order, class, phylum or kingdom) is very weak, and far from conclusively points to one animal being able to turn into another, even over a series of macroevolutions. I have friends who study evolutionary biology whom I've discussed this with at length, and they are very reticent to admit that the incidents cited in that article are macroevolution observed on the level we are actually discussing.



Considering that (1) is more like "essentially a guarantee" and that (2) is probably dependent on little else than the planet being a couple billion years older than us, "a snowflake's chance in hell" is the definition of an uneducated guess. We can forget about (3) entirely, since any guess you make about it is predicated entirely on your limited sociological point of reference. What if only two people survived an exodus to our planet? There's just not even any point in speculating it, let alone trying to account for it.

Am I saying that it's likely? Not really. I'm saying that even if it's incredibly rare, it could still occur a billion times. You can't definitively say that something is unlikely when you don't even have a clue how big the population you're studying is, and considering we've only even identified a few hundred planets of what could easily be billions or greater, it's incredibly naive to take a de facto stand that our planet is special.

Yeah. Except no.

Yep. They know more about it than us and you've talked to them therefore you're absolutely correct. Sorry to say, but if your friends have gotten to the graduate level of evolutionary biology and don't think there's enough evidence to conclusively point to macroevolution, they're likely to be morons. This is beside the point that you were challenged with data and replied with an argument from authority. I normally try to take the sympathetic position on these scientific threads, but you're being an cnut.

If you're going to make lazy unsubstantiated claims that you can't back up except in varying versions of "But I bet it's true 'cause space is big!" then why are you bothering?


I said exactly what I believe -- we don't have anywhere near the amount of evidence to form a belief in life on other planets except as wishful thinking. Saying "But it's big! Really big!" doesn't make it "essentially a guarantee". You haven't said anything yet more convincing than that you really, really think it must be true. Given that you're the one making the statement that it's "essentially a guarantee", perhaps you should be more worried about backing that up and showing that you're right instead of insisting that I prove you wrong.

You say that but I've yet to see anything different.


Apparently the meaning of "essentially a guarantee" has changed since last I checked. Or are you relying on "essentially" to be your weasel word. "I only said essentially a guarantee!"


I shouldn't be sure that I'm right about a lack of evidence making life on other planets "essentially a guarantee"? Yeah, I'm feeling okay about that claim especially given the contradictory "evidence" presented thus far.


Aside from the lack of any evidence to base an "extrapolation" on besides "But it's really big!", you mean.

Yeah. Wishful thinking. But I do admit that one uses bigger words so I guess it sounds like it might be more true provided you don't think about it.

Edited, Dec 6th 2010 1:34am by Jophiel

Don't pretend like the "essentially a guarantee" comment was pertinent to our discussion. I was talking specifically about microbial life with that comment, and I made that comment later and out of context to the discussion we were having. This debate hasn't fundamentally changed in the slightest since that comment.



We have sufficient evidence for inferential extrapolation-- we have US, and we have our observation rate. Currently, at best we can conclude that life exists on 1 out of roughly 400 planets observed out of roughly an extrapolated ~1 billion unobserved planets (based on stars:planets). Because we have yet to observe a statistically significant sample of subjects, inference is the only tool we have to rely on. Essentially, at this point we have more reason to believe that 1/1000 planets have life on them than to believe that NO other planets have life on them. That's not tautology, unless you think that inferential extrapolation is tautological. If you'd like to argue that point, I'd welcome the discussion.



His assertion, if I understood it correctly, was that evidence pointed to it not being the case, which is a claim that can really only be made with regards to an assumption like normality where we don't have nearly enough data to employ a test of normality. However, if we were to extrapolate data to assume normality, it would be more likely that there were life elsewhere than not.

This confusion about me saying that it is "nearly certain" should be clarified. I'm not actually saying that, and my statement was outside of the current context of the discussion. Shinta said that the probability of life elsewhere (which I took to include the simplest life) was enough to entertain reasonable doubt, and I replied that it was "more like" essentially certain. So we can quibble about it or suspect me of backpedaling, but my intention was not to express that the probability of life was =.999999999, but to say that reasonable doubt (which could be =.05 for all I know) is less like the actual likelihood than .9999999 is. e.g., if it's safer to guess a likelihood of something like .7.

As for Drake's equation, no, though that looks like it has some fundamental similarities. I just made a cursory glance of the wiki on it, but it doesn't factor in certain pertinent data and seems to ignore statistical normality more or less completely. It could probably be adapted easily enough to express something with actual substance though. I would agree that it relies on too many unknown data points to be at all useful. You can only extrapolate so far-- the more you extrapolate on extrapolated data, the weaker your case, though you can still have a decent one with prominently extrapolated figures (and in most cases in the natural world where the data is known, it does in fact work). That equation starts from one data point (which is smaller than the figure you would use for the purposes of our discussion) and extrapolates everything else. I wouldn't say that it's totally useless, but practically useless.

Wow, that's some pretty frantic backpedaling there. So you're making statements and then throwing a fit when I call you on them and then refusing to back them up, saying "It's not important! Look at this other argument!"?

Oh, hi Gbaji.


That is completely meaningless.


No, we don't.

Go ahead and keep ******** that I'm not fleshing out an argument to "But it's really big" well enough for you. Or pretending that what you said was anything more substantial than saying "It's really big".

Damn, I was holding off on returning to this thread thinking that I'd have more time to adequately address arguments later, and instead I find nothing but a bunch of non-arguments.



Then please accept my invitation to correct me: Has macroevolution beyond speciation been adequately substantiated or is it still theoretical? And I'll be sure to extend your invitation to have my friends suck your balls should you demonstrate them to be wrong.

And don't misunderstand me: I think it's foolhardy not to subscribe to macroevolution as the explanation for earth's biodiversity. I'm just under the strong impression that we haven't observed it on the level relevant to this discussion.



It was a miscommunication that was deservedly clarified, and nothing else. I'm trying to give you the benefit of the doubt that you're genuinely misunderstanding me, and not doing it on purpose.

My essential argument hasn't changed. Given the naturally occurring rate of the building blocks of life, the probability of those being present individually (which itself is relatively high), we can extrapolate an educated guess at the probability of them occurring together. Since we can further extrapolate that there are probably trillions of planets (or more), we can ultimately guess that there could likely be life-sustaining planets in this galaxy alone, nevermind the billions of others. As I alluded to before, the odds of being an outlier are rare. Normality is generally the default position of the natural sciences, not freak accidents.

I don't know, I'm not an astrophysicist or anything, but people like Frank Wilczek and Stephen Hawking throw their weight behind it and it makes perfect sense to me. I didn't even pick it up from anyone else; just pieced it together from the evidence and methods I know of. Edification of authority maybe, but until I hear better arguments than "we haven't seen it so we don't know," I guess I'll just respond with snarky ******** like everyone else.