Firlefanz
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Intelligent Life out there?
Here's an article with new calculations for finding intelligent life in space.
What Are The Odds Of Finding Extraterrestrial Intelligent Life?
Blurb: Is there anybody out there? Probably not, according to a scientist from the University of East Anglia. A mathematical model produced by Prof Andrew Watson suggests that the odds of finding new life on other Earth-like planets are low, given the time it has taken for beings such as humans to evolve and the remaining life span of Earth.
Does this make any sense?
--- - Firlefanz
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4/20/2008, 5:06 pm
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Reythia
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Re: Intelligent Life out there?
If I could get this board to accept the full words abbreviated B.S., I would here. And I'm not talking "baloney sausage" or "bachelors of science", either! I despise this sort of article. I wish Drake had never written his little equation, because it means scientific funding goes to useless, unprovable things like this rather than anything that might be meaningful in some way. *growl!*
quote:
Solar models predict that the brightness of the sun is increasing, while temperature models suggest that because of this the future life span of Earth will be ‘only’ about another billion years, a short time compared to the four billion years since life first appeared on the planet.
This is something I have never heard and am very skeptical about. I don't claim to be enough of an expert in the subject to flat-out deny it, but everything I learned in my several astronomy classes contradicts this. And at least one of those classes was taught by a guy whose primary research is on the internal dynamics of stars... (Anyone else hear differently? 1 billion years is a LOT different than the 3-5 that I've heard.)
But THIS is my main problem with this article and others like it:
quote:
If we learned the planet would be habitable for a set period and that we had evolved early in this period, then even with a sample of one, we’d suspect that evolution from simple to complex and intelligent life was quite likely to occur.
So in other words, since the ONE planet that we know has life on it developed in THIS way, that means ALL life on ALL planets must develop that way. I'm sorry, but anyone who's ever studied even basic probability knows that that doesn't make any sense. That's like flipping a coin ONCE and, since it landed heads, deciding that that means that ALL coins will ALWAYS land heads.
Until we have more evidence, we cannot and SHOULD not make statements like these.
And does anyone notice anything WRONG about this line:
quote:
Each step is independent of the other and can only take place after the previous steps in the sequence have occurred.
Ummm... If they're INDEPENDENT, then why do they have to occur one after the other?! To be fair, this is probably a mistake by the writer, not the scientist, but it doesn't improve my already unimpressed opinion of the piece!
---  -- YAR! |
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4/21/2008, 4:39 pm
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QS2
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Re: Intelligent Life out there?
I'm afraid I'm going to have to disagree with Reythia on this one, the author seems to be right on most counts.
quote:
Solar models predict that the brightness of the sun is increasing, while temperature models suggest that because of this the future life span of Earth will be ‘only’ about another billion years, a short time compared to the four billion years since life first appeared on the planet.
What is being referred to here is not the end of our sun, but the moment when our sun becomes so bright that it will boil our planets oceans off, despite greenhouse gases being essential zero. It seems unlikely that life as we know it will survive a catastrophe of this magnitude.
As for the brightening, yeah, that is really happening. Geological research has shown the sun to have been considerably less bright hundreds of millions of years ago and the CO2 levels seemingly were a bit higher then to compensate for this.
quote:
So in other words, since the ONE planet that we know has life on it developed in THIS way, that means ALL life on ALL planets must develop that way. I'm sorry, but anyone who's ever studied even basic probability knows that that doesn't make any sense. That's like flipping a coin ONCE and, since it landed heads, deciding that that means that ALL coins will ALWAYS land heads.
Until we have more evidence, we cannot and SHOULD not make statements like these.
It is possible to make some statistical guesses from a sample of one, they just aren't necessarily very representative. How ever getting back to the article, what they are trying to say is, imagine humans (intelligent species) evolved within a million years of the Earth (planet) becoming habitable. If that had indeed occurred, then it would be suggestive that you didn't necessarily need a lot of time to evolve yourself some humans (intelligent species) and you'd have really good chances then if you had billions of years to wait for some intelligence to show up. And thus equally logically if it took billions of years to evolve the first human (intelligent species) to evolve, then maybe it could take very long and so you wouldn't have many chances in a few billion years.
Of course with a sample of one this isn't very definitive though, but scientists being scientists so me of them thought of a different way to perhaps improve the sample quality amount a bit. And they did this by statistically analyzing the rate of important evolutionary changes instead. This was was mentioned in this article as well so I guess they looked into that as well. Now the idea behind this is, is that usually the time between difficult evolutionary events is determined by just how difficult they are. In example, if it is really difficult then step 1 might take a billion years on average, if step 2 is really easy in comparison maybe that happens on average every ten million years and step 3 is somewhere in between that on average and say takes 100 million years roughly.
So they ran some simulations and such on this which seems to make this idea more likely and that usually you'd see the average distribution except in say for instance time constrained situations. (Lacking further planets with life to study right now we'll have to make do with models I guess  ) Now usually in a time constrained system you simply wouldn't make it before your planets livable lifetime is expended, however there these things are somewhat chance based, there would also be a chance of all of these events happening unseasonably quickly. However it turns out in the model that when you are greatly time constrained that normal distribution just vanishes and instead you get a random distribution, which means that usually the events become roughly evenly spaced.
What this all means is, is that if you find equal intervals between difficult evolutionary phases, then there is an increased likelihood that the evolution on this planet happened within a compressed time frame, which would indicate that normal evolutionary time frames should be considerably longer. Now the article itself states it found such a relationship, which would indicate that not only did it take long on this planet to get human life, it even seems likely that even this was pretty compared to what it should have been.
The article then goes on to state some chances, which I suspect they don't have much basis to claim further ,especially because they give everything equal chance, which is almost for sure wrong when looking at each of these evolutionary steps in a biological sense. Where some of these steps seem much more difficult then others (ie making any life at all from just basic chemical reactions in the oceans seems harder then going from complex life to intelligent life to me) But I don't know their model, so who knows. But their claim is thus not completely without merit.
quote:
Each step is independent of the other and can only take place after the previous steps in the sequence have occurred.
I think this refers to that each step can only happen when the step before it has completely finished, they can't happen simultaneously and as such never overlap, ie you can't do two steps simultaneously. I guess choosing independent to describe that was a bit poorly thought out. 
PS This certainly is provable, for a definitive test you 'merely' need to seed a few million habitable planets with simple life and study their evolutionary progress over a few billion years.  (No problem at all, what?  )
More seriously though, I hope you can see this wasn't as unscientific as you thought and as such does deserve some funding to continue to further work things out, you never know what will be useful after all.
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4/22/2008, 8:13 am
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Reythia
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Re: Intelligent Life out there?
quote:
QS2 wrote:
quote:
Solar models predict that the brightness of the sun is increasing, while temperature models suggest that because of this the future life span of Earth will be ‘only’ about another billion years, a short time compared to the four billion years since life first appeared on the planet.
What is being referred to here is not the end of our sun, but the moment when our sun becomes so bright that it will boil our planets oceans off, despite greenhouse gases being essential zero. It seems unlikely that life as we know it will survive a catastrophe of this magnitude.
As for the brightening, yeah, that is really happening. Geological research has shown the sun to have been considerably less bright hundreds of millions of years ago and the CO2 levels seemingly were a bit higher then to compensate for this.
Yes, I understand. However, this very much counters what I've learned both in my astronomy classes and on my Earth-science research. Check out these two references (both, admittedly, pulled randomly off the web via a Google search for "brightness of the sun over time")
Sun at Peak Brightness
Solar Cycle and Climate Change
Both of these sources (as well as other things I've read previously) say:
1.) The sun IS brighter now than it has been in recorded human history
2.) However, it HAS been as bright or brighter in the past (~8000 years ago, according to the first site, though I've seen different numbers by as much as an order of magnitude).
3.) The change in the Sun's intensity follows (we think!) a superpositioning of several different sinusoids ("the sun's 75-90-year "Gleissberg Cycle," the 200-500-year "Suess Cycle" and the 1,100-1,500-year "Bond Cycle" according to the second site). At the moment, they are all more-or-less "in-sync" and thus the total intensity is large. As they get less "in-sync", the magnitude will begin to decrease.
4.) There may be more longer-period cycles piled on this that we don't understand, and there ARE shorter-period ones, like the 11-year sunspot cycle. That means it's still possible that the sun COULD get noticably hotter than now -- but it's still unlikely to continue increasing in temperature and brightness indefinitely. I have never before seen a number like the "one billion years" that the researcher in the article stated, nor have I read of a confirmed linear trend in solar brightness (on the billions-of-years scale, that is). As I said before, I don't claim to be an expert on the subject, but that DOES suggest to me that it's a topic still under discussion, at least. At the moment, I would not trust one number over another.
5.) If the "one billion years" was actually derived from solar nuclear dynamics (which may not be included in the above cycles), then why didn't my prof -- who STUDIED such things -- mention it? Again, not proof that it isn't true, but enough to make me seriously skeptical.
(I'll get back to the rest of QS's post in a sec. Must check on my computer job first!)
--- -- YAR! |
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4/22/2008, 4:45 pm
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Reythia
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Re: Intelligent Life out there?
The remainder of my argument isn't about the type of logic the researcher is using, but rather that I see very little benefit in making such predictions until we have more data. One data point does NOT make for good predictions. EVER. Even if, as chance would have it, your prediction ends up close to correct, that's not because of anything YOU did. Trusting on blind chance, where you cannot even make a decent estimate of your errors, is not scientific and does not deserve to earn what limited scientific funding is out there. Perhaps it would bother me less, but the way this article was worded, it sounds like there is NO chance this hypothesis could be wrong -- which is just plain ridiculous.
quote:
PS This certainly is provable, for a definitive test you 'merely' need to seed a few million habitable planets with simple life and study their evolutionary progress over a few billion years. emoticon (No problem at all, what?)
Exactly, QS. This I agree with -- and yes, I realize that at this point it's completely impossible.  Which is unfortunate, since I think if there was any real data -- the classic "30 points of data" to make things statistically relevant, even -- then this would be a valid, interesting study. But until that data exists, we're just guessing blindly.
That's my problem with Drake's Equation in general (which this is a subset of). If we had any good idea whatsoever of what all the fractions were, we'd have a good estimate of how likely it would be to contact an alien race. But since we don't, it's functionally useless for anything but excellent scifi stories. Both Drake and the guy in this article have practical, intellegent series of logic working for them -- they're RIGHT in that sense. But until they have data to fit to their predictions, those equations are functionally useless. That's unfortunate, but true.
Here's a simple example of why I'm so strongly against this sort of thing:
Let's pretend that I'm an alien. Purple skin, big tentacles, the whole shebang. I fly over to Earth in my invisible spaceship and decide to beam a human up to my ship for *hehehe!* "investigation". So I pick up the first individual I find. Totally random. Let's say his name happens to be Nenad. He's an aerospace engineer from the Netherlands, now working in the US. I observe him, probe him *s****!*, if you will. Then I dump him back down on Earth and turn my spaceship around to head home with my results.
On the way home, I write a scientific paper in which I declare that based on my one sample, the average human:
1.) Is 7 feet 2 inches tall (bit under 2.5 meters)
2.) Weighs 150 lbs (about 70 kg)
3.) Is an expert in airplane design
4.) Likes kayaking
5.) Has traveled all over the globe
etc.
My data accurately reflects Nenad. It does NOT correctly reflect humanity as a whole. In the same way, an analysis that only uses the Earth as a sample -- no matter how accurately it describes the Earth -- cannot be assumed to represent non-Earth planets. It just doesn't make sense.
--- -- YAR! |
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4/22/2008, 5:07 pm
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QS2
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Re: Intelligent Life out there?
quote:
Yes, I understand. However, this very much counters what I've learned both in my astronomy classes and on my Earth-science research. Check out these two references (both, admittedly, pulled randomly off the web via a Google search for "brightness of the sun over time")
Sun at Peak Brightness
Solar Cycle and Climate Change
Ok, what we are talking about here is solar nuclear dynamics I guess in specific the cores nuclear fusion process against the stars gravitational equilibrium. Basically what is happening here is that the sun produces more helium over time which reduces net output of energy from fusion, because the helium gets in the way. However gravitational contraction does not decrease and so the core will keep contracting, leading to increased pressure and temperature until the core does produce enough fusion power to balance the gravitational contraction again. (At least, I thought that this is what is happening)
So basically the star is getting hotter over time and so the absolute brightness of the star over millions of years is slowly rising. I believe the amount we are looking at only amounts to 20-50% percent, so it isn't huge and perhaps a stellar physicist would thus rate it as a detail. However for planetary climate stability, that kind of intensity shift is huge. And so it is thought that in a billion years from now the sun will be so bright that further reductions of CO2 will no longer be able to cancel the effects anymore and we'll start losing the oceans and well, it's all downhill from there.
quote:
The remainder of my argument isn't about the type of logic the researcher is using, but rather that I see very little benefit in making such predictions until we have more data. One data point does NOT make for good predictions. EVER.
As usual using the word 'ever' in science is dangerous. Turns out one data point can be useful, if you can but sufficiently qualify your data and the reliability of your measuring system is high enough. In general the second is not the case and mostly you can't really qualify things all that well either. However in this specific case some qualifications could be made as I was pointing out and this somewhat constrains the possible amount of errors you can have from this single data point we have on life.
As for the drake equation, unless we try to quantify it, how ever will we know if we can? Anyway, it turns out that we are managing to quantify ever larger parts of it (Due to our discovery and study of other planetary systems) and our largest problem by now is pretty much starting to become quantifying the chances of life and its evolution. Which is why increased scrutiny is being brought to bear, trying to squeeze every last drop of qualitative data we can get from our single data point. Sure, we'll probably not get very far in that, but you never know till you try. Personally I find it interesting that qualitative analysis indicates that it is unlikely that the time range is long and so most likely typical evolutionary lines should be longer yet.
PS If you also add things in like anthropic principle and the Fermi's Paradox, you get further indications that our evolutionary time frame was likely short compared to the overall mean.
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4/22/2008, 8:32 pm
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