"Milky Way has been cracked like a pinata" New stuff top pg5

[Fireball1244]

28 worlds with higher life forms. How many of those will develop sentient life? It only happened once on earth after billions of years, so the odds seem pretty low. But let's be generous again and say half.

Has sentience only developed once? Are we sure dolphins aren't sentient? They can communicate and use tools. Do all of the other hominid offshoots that have since gone extinct, ones not in our direct evolutionary line such as Neanderthals, count as part of our instance of sentience or are they separate, though extinct, examples of sentience? Not nitpicking, just proposing some notions for discussion.

7 worlds with technological civilizations. One of them is us, so 6 others. How many of those will reach our level of sophistication? Half?

3 civilizations comparable to ours. How many of those will be so far ahead of us that they can travel among the stars or invest time and energy in automated probes that take thousands of years to reach their destinations? Again, we're in the realm of pure speculation. If your answer is 1/3, then there is one. If your answer is under 1/3, there aren't any.

One thing to consider is that another world that's about earth's age, with sentient, technological life forms, could have seen those lifeforms first reach a civilized state when our world was populated by dinosaurs. If that planet hasn't suffered a process-reseting asteroid impact, that could mean that they are hundreds of millions of years more advanced than us, to a degree that we could be looking at their planet, but not recognize the presence of a civilization because we wouldn't recognize what to them would be clear evidence.

[Defiant]

7 worlds with technological civilizations. One of them is us, so 6 others. How many of those will reach our level of sophistication? Half?

I think it would be more than that. What would stop a technological civilization from reaching our level of civilization?

1. Their civilization was destroyed. If it was by, say, nuclear war, that would pretty much mean they reached our level of civilization. Otherwise they were killed by a planet wide catastrophe (eg, Asteroid impact), but those generally don't happen very often here, and probably don't happen that often on any planet that has been stable enough to foster a technological civilization.

2. They are in the "dark ages", not curious, or don't have war and therefore don't gain the amount of scientific advancement we generally see from war. But they have to be at least somewhat curious, as they've seen some advancement, and will, I believe continue to see some (low) level of advancement, even if it takes 10 or 20 times as long as it did for us. And while it's possible that their equivalent of the church or the state or business or something else might prevent their advancement, I think it unlikely that it can do so indefinitely.

Any other likely possibilities?

Edit: I suppose another possibility is really short lifespans that can't be improved. Imagine if we could only live til 20 or 25. Still, I think many of the pre-20th century knowledge/advancement that didn't require corporations or long time to develop might be possible (eg, they might eventually understand the basics of electricity. Maybe even radio?) But I think it' less likely that a species like that would have developed a technological civilization to begin with.

[RunningMn9]

I don't believe anywhere I discussed probabilities. I merely said that there are many more factors required by life than mere liquid water. That said, the more factors something requires, the more rare it will be compared using only one of those factors.

See? You are discussing probabilities.

Actually we have no reason or evidence that there is anything more than this composition since life as we know it is all we have evidence for. I think the burden of proof is on you for this one.

Just once, would it be possible to just have a friggin' conversation around here without pretending that we are debating at the Royal Academy of Science using the Queen's Rules? Holy Underpants.

There is no burden of proof on me because I am not making a positive assertion. I'm not telling you that there are other compositions of life. I'm saying that you (or rather the side that you are representing here) hasn't met the burden of proof that this is the only possible composition of life. We don't know because we are far too ignorant as to what is going on out there in the universe. And if "all we have evidence for" is good enough, then clearly *all* solar systems have a rocky planet in the habitable zone that sustains an "advanced" civilization, since right now, 100% of solar systems that we have detailed information about have them. Right?

You're assuming your sample size (the universe) is large enough to outweigh the improbabilities. But the problem is you don't know that.

I know that in the context of the statement that I actually made (with the disclaimer that you removed). As long as the probability of hosting advanced life is greater than 1 in 10,000,000,000,000,000,000,000 then advanced civilizations are abundant in the universe.

Indeed, you're merely assuming what you need to prove.

No, as I provided the necessary qualifier to my probability calculations.

You can make anything appear likely if you stack the odds in your favor

Kraken used a 1 in 2 chance to stack the odds in his favor. Presuming a probability of 1 in 10,000,000,000,000,000,000,000 is not stacking the deck in my favor. A 1 in 10 sextilliion chance is several orders of magnitude more remote than other estimates I've seen (which are in the trillion scale).

Until you establish the likelihood of life developing more than once, you've only got one side of your analysis.

Again, all I said was "*IF* the chance of advanced civilization developing around a star is 1 in 10 sextillion, there are enough stars in the sample set such that there are a hella lot of advanced civilizations (according to the probabilities). And I even simplified it down for you. If you flipped a coin 200 times, you'd probably end up with a lot of heads. That's the kind of frequency we are talking about - *IF* the probability of an advanced civilization developing around a star is as remote as 1 in 10,000,000,000,000,000,000,000.

It is entirely possible that the likelihood of life developing more than once is so low as to outweigh the size of the universe. Maybe, maybe not. But nowhere have you attempted to quantify this probability based upon any scientific basis.

Actually, I did calculate exactly that in the other thread, in the context of my incredibly remote estimate of the probability of life. Given the number of iterations available, the probability that life would develop only once, was twice as remote as the possibility that it would develop at all (1 in 10,000,000,000,000,000,000,000,000,000,000,000,000,000,000). Or, to simplify it so that one could process it in a reasonable fashion, the probability that life would develop once and only once is equivalent to the probability that you would flip a coin 200 times and get only one head.

Assuming that the probability of life is as remote as 1 in 10,000,000,000,000,000,000,000 of course.

I'll give you a perfect example from the links I gave above. According to scientists, not only do solar systems have a habitable zone but so do galaxies. In our own Milky Way only 10% of the stars exist in this habitable zone. So in just one fell swoop, looking at one variable, science has knocked out 90% of your septillion stars (assuming for the moment that this also applies to other galaxies - we can go futher into galaxy types if you want to). The universe just got a lot smaller

Uh, no, it doesn't quite work that way. Your statistics really is rusty.

You are providing the data points that go into calculating the "1 in 10,000,000,000,000,000,000,000" probability of life, not directly reducing the number of iterations. You don't get to double down and do both. You can reduce the sample set of stars to 100 sextillion, but if you do that, you have to remove that factor from the probability of life side, which increases the probability of life to 1 in one sextillion.

And thus the equation ends up with the exact same results as before.

[El Guapo]

A 1 in 10 sextilliion chance is several orders of magnitude more remote than other estimates I've seen (which are in the trillion scale).

Heh. You said "sex".

[Defiant]

I was deliberately over-generous at several steps for tripcow's sake. For all the reasons you mentioned, complex life is probably extremely rare. I expect that the galaxy is infested with germs, though. Maybe even moldy.

Personally, I think the leap from no life to life (assuming one considers germs life) is the bigger one than from life to intelligent life - unless the primordial soup that is life's equivalent of the big bang is not rare. if there are germs out there (especially if they've infested the galaxy) I'm willing to believe that there are lots of complex life out there.

[Kraken]

28 worlds with higher life forms. How many of those will develop sentient life? It only happened once on earth after billions of years, so the odds seem pretty low. But let's be generous again and say half.

Has sentience only developed once? Are we sure dolphins aren't sentient? They can communicate and use tools. Do all of the other hominid offshoots that have since gone extinct, ones not in our direct evolutionary line such as Neanderthals, count as part of our instance of sentience or are they separate, though extinct, examples of sentience? Not nitpicking, just proposing some notions for discussion.

All valid observations that I deliberately ignored to simplify my response to tripcrow, although I think I did dismiss dolphins as slackers. "Sentience" in the sense of self-awareness certainly exists in multiple forms on earth, and "intelligence" (which is more relevant) exists on a continuum. There aren't sharp lines between sentient/non-sentient and intelligent/unintelligent. Since thought and behavior don't fossilize very well, we can't say much about the history of non-human, non-technical intelligence. There might have been some very clever and witty dinosaurs.

What we can say is that intelligence is just another survival mechanism. So the specialization has worked out exceptionally well for one species. But many feel that it will ultimately prove mal-adaptive unless accompanied by wisdom, altruism, social cooperation, etc.

Any other likely possibilities?

They might not have evolved the capacity for language. Civilization depends on symbolic abstraction, social cooperation, education and enculturation, none of which might have happened without the subtle physical changes that enable us to speak.



Regarding the radio signals that the earth has sent out (and any that we might receive), people forget that the earth is not a stationary broadcasting point. It's turning on its axis and orbiting the sun, which is itself moving relative to other stars. The unfocused shell of radio signals that we spew into space might be recognizable as artificial, but even the most careful observers can't reconstruct coherent episodes of Gilligans Island.

OK, bad example: There were no coherent episodes of Gilligans Island.

[Defiant]

They might not have evolved the capacity for language. Civilization depends on symbolic abstraction, social cooperation, education and enculturation, none of which might have happened without the subtle physical changes that enable us to speak.

Yeah, I can't imagine being able to communicate without using my voice. It's a good thing we don't have any people who don't use their voice to communicate. Animals communicate without voice (eg, bees) as well. And I would thing that any low level technological civilization would need some form of communication to begin with in order to pass knowledge down.

The unfocused shell of radio signals that we spew into space might be recognizable as artificial

I would assume that would be sufficient for our purposes.

[Holman]

Just curious: what is the range of the the radio and other media signals we've been accidentally broadcasting into space? Is it effectively infinite, or do the signals loose strength/coherence and peter out at some point? I know we can study stellar radiation from umpteen *illion light years away, but are human-made signals so robust?

I wasn't entirely asleep in tenth-grade science, but I don't know if our radio waves get overwhelmed and scrambled by other forms of radiation or what.

[tripcrow]

That was one of the excuses used to cut NASA SETI funding. Think it went something like by the time the waves they were seaching for reached even the closest star they wouldn't be discernible. Obviously some knowledgeable people disagree.

[RunningMn9]

I was looking over the Drake equation as I was thinking about this, and aside from a few things that I'm not sure about (why it never considers the number of stars in our galaxy, but only the rate of star creation - although I suspect that it is a result of the Drake Equation applying to the number of advanced civilizations that can communicate with us, as this time), it at least gives us a starting point.

A modified version of the equation, that is just trying to establish the number of instances of intelligent like in the milky way would look like so:

N = S * fp * ne * fl * fi, where
N = number of instances of intelligent life
S = number of stars in the Milky Way
fp = fraction of those starts that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life

The current estimates of the parameters:
S = 100,000,000,000
fp = at least 0.4
ne = between 0.1 and 0.2 (10-20%)
fl = 0.13
fi = 0.01 (this is the one that people croak about the most)

Using those parameters, you have:

N = 100,000,000,000 * 0.4 * 0.1 * 0.13 * 0.01
N = 5,200,000

Now, I understand the criticism of the Drake Equation, and I understand the "guessy" nature of these parameters. What I have been trying to impress upon Grifman is the absolute unpossible-to-comprehend enormity of the Universe. The above parameters yield about a 1 in 20,000 chance of a random star developing intelligent life based on that equation.

1 in 20,000

I chose 1 in 10,000,000,000,000,000,000,000 and I am being accused of loading the dice in my favor?!? Are you kidding me?

The current estimates for that equation suggest that there should be over 5 million instances of intelligent life in the Milky Way. My calculations assumed that you only see *one* instance of intelligent life in each group of 5 million Milky Way-like galaxies. And I'm stacking the deck in my favor?!?

The Universe is *impossibly* large. There is no way to come up with numbers small enough such that there aren't billions of instances of intelligent life out there. It doesn't matter how small you want to get, the size of the Universe quickly overwhelms them.

[Grifman]

Got a new PC, working on getting that up and running so it will be a couple of days before I get everything installed, files transferred, other stuff set up. Just so you don't think I'm ignoring you

[RunningMn9]

Got a new PC, working on getting that up and running so it will be a couple of days before I get everything installed, files transferred, other stuff set up. Just so you don't think I'm ignoring you

Fair enough. Just remember that in the two days it will take you to post there will be roughly 8 billion new stars in the universe.

[Enough]

Got a new PC, working on getting that up and running so it will be a couple of days before I get everything installed, files transferred, other stuff set up. Just so you don't think I'm ignoring you

Grats on the new rig!

[msduncan]

I was looking over the Drake equation as I was thinking about this, and aside from a few things that I'm not sure about (why it never considers the number of stars in our galaxy, but only the rate of star creation - although I suspect that it is a result of the Drake Equation applying to the number of advanced civilizations that can communicate with us, as this time), it at least gives us a starting point.

A modified version of the equation, that is just trying to establish the number of instances of intelligent like in the milky way would look like so:

N = S * fp * ne * fl * fi, where
N = number of instances of intelligent life
S = number of stars in the Milky Way
fp = fraction of those starts that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life

The current estimates of the parameters:
S = 100,000,000,000
fp = at least 0.4
ne = between 0.1 and 0.2 (10-20%)
fl = 0.13
fi = 0.01 (this is the one that people croak about the most)

Using those parameters, you have:

N = 100,000,000,000 * 0.4 * 0.1 * 0.13 * 0.01
N = 5,200,000

Now, I understand the criticism of the Drake Equation, and I understand the "guessy" nature of these parameters. What I have been trying to impress upon Grifman is the absolute unpossible-to-comprehend enormity of the Universe. The above parameters yield about a 1 in 20,000 chance of a random star developing intelligent life based on that equation.

1 in 20,000

I chose 1 in 10,000,000,000,000,000,000,000 and I am being accused of loading the dice in my favor?!? Are you kidding me?

The current estimates for that equation suggest that there should be over 5 million instances of intelligent life in the Milky Way. My calculations assumed that you only see *one* instance of intelligent life in each group of 5 million Milky Way-like galaxies. And I'm stacking the deck in my favor?!?

The Universe is *impossibly* large. There is no way to come up with numbers small enough such that there aren't billions of instances of intelligent life out there. It doesn't matter how small you want to get, the size of the Universe quickly overwhelms them.

Rare moment here.... but I completely agree with RM9.

[Rip]

I don't see why you guys need all this math to decide there is intelligent life out there. You could have just asked Sammy Hagar.

This was long before computers or any kind of wireless,” says Hagar of his experience in the foothills above Fontana, CA. “There weren’t even wireless telephones. Looking back now, it was like, ‘F___, they downloaded something into me!’ Or they uploaded something from my brain, like an experiment. See what this guy knows.

We may have him to thank for them apparently defunding the project. Citing him as proof that if their was no intelligent life on earth.

[noxiousdog]

Show me even one rocky world with a stable orbit in the biozone that possesses an oxygen/nitrogen atmosphere and I'll happily make the next leap with you.

Why is CHONPS so important?

I don't know because you didn't tell me what the hell is CHONPS and I don't feel like googling it today

carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. It was how we learned the basics for what must be present for LIFE as we know it. Arsenic bacteria was using Arsenic instead of phosphorus which is what made it so cool.

It makes it cool, but very unlikely. Even still arsenic is chemically similar to phosphorus, just not as stable.

We can think of all kinds of chemical posibilities, but in reality there's probably only a certain amount that are stable enough to work.

[tripcrow]

Thanks to a new report by a group of European astronomers the relevance of the Fermi Paradox question to our continued existence just gained a great deal of importance.

“our galaxy has maybe ten or 20 billion Sun-like G stars, but is home to 150 billion M-dwarfs, and maybe more, adding up to some 80% of the galaxy's stellar population.”

“All the same, given M-dwarfs' ridiculously high, almost beetlesque, numbers, you could cut out all the M-dwarf planets that were too big, and those that were outside the stars' habitable zones, and those where changes in radiation and brightness were outside acceptable ranges, and still end up with a huge number of potentially life-friendly planets. And that makes them perhaps the most promising targets in the search for alien organisms that the planet-hunting community is ever likely to find.”

http://news.yahoo.com/billions-planets- ... 00332.html

I heard an interesting argument a month or so back that junk DNA, the 98% of our DNA that seems to serve no purpose, may be the means used for first contact by other intelligence. The argument goes that about the time a life form is able to read it they should be able to space travel. Junk DNA has been getting some attention recently because it is being used by some as an argument that if there is or was a creator he wouldn’t waste all that DNA and the counter arguments. To my thinking if there is some phone home message in our DNA it would of course give the galactic confederation theory a real boast. But it wouldn’t make our life form’s seemingly eventual self-destruction any less likely. Intelligent life isn’t as rare as the slow to adapt establishment would have us believe. But intelligent life capable of evolving much past where we are now is. Nor would a DNA phone home message change the odds that reality is just a simulation written in math for some futuristic quantum computer thingie. I'm figuring I'm in this sim for educational purposes. Definitly not a vacation. Or I will be asking for a refund.

[noxiousdog]

I heard an interesting argument a month or so back that junk DNA, the 98% of our DNA that seems to serve no purpose, may be the means used for first contact by other intelligence.

This struck me as the "we only use 10% of our brains argument so I went looking. I understood about 10% of it, (coincidence? I THINK NOT!) and found this on wiki:

Many noncoding DNA sequences have important biological functions as indicated by comparative genomics studies that report some regions of noncoding DNA that are highly conserved, sometimes on time-scales representing hundreds of millions of years, implying that these noncoding regions are under strong evolutionary pressure and positive selection.[17] For example, in the genomes of humans and mice, which diverged from a common ancestor 65–75 million years ago, protein-coding DNA sequences account for only about 20% of conserved DNA, with the remaining 80% of conserved DNA is represented in noncoding regions.[18] Linkage mapping often identifies chromosomal regions associated with a disease with no evidence of functional coding variants of genes within the region, suggesting that disease-causing genetic variants lie in the noncoding DNA.[18]
Some specific sequences of noncoding DNA may be features essential to chromosome structure, centromere function and homolog recognition in meiosis.[19]
According to a comparative study of over 300 prokaryotic and over 30 eukaryotic genomes,[20] eukaryotes appear to require a minimum amount of non-coding DNA. This minimum amount can be predicted using a growth model for regulatory genetic networks, implying that it is required for regulatory purposes. In humans the predicted minimum is about 5% of the total genome.

Regardless, count me as firmly in the, if there were intelligent life, we would have seen it camp.

[msduncan]

Regardless, count me as firmly in the, if there were intelligent life, we would have seen it camp.

Do you mean to say that you think we are the only intelligent life in the galaxy, the Universe, or the area of the galaxy that we reside in?

If you think we are the only ones, then it's truly a miracle that we as individuals are here. Whether you think it's a divine miracle, or whether you think it's a scientific miracle is up to you.

[RunningMn9]

Regardless, count me as firmly in the, if there were intelligent life, we would have seen it camp.

I totally agree. We've spent a tiny fraction of our history examining a vanishingly small fraction of the universe will exceptionally rudimentary methods for detecting intelligent life.

If that isn't enough to locate intelligent life in the universe, I don't know what is!

[msduncan]

Regardless, count me as firmly in the, if there were intelligent life, we would have seen it camp.

I totally agree. We've spent a tiny fraction of our history examining a vanishingly small fraction of the universe will exceptionally rudimentary methods for detecting intelligent life.

If that isn't enough to locate intelligent life in the universe, I don't know what is!

I agree with RM9's sarcasm.

Life would be so completely diversified that how do we even know these creatures invented any technology that we are listening for? How do we know they would have invented something to send out radio signals?

It's always surprised me how close minded scientists are to the idea that life, and advanced life, has probably evolved from an entirely different sets of rules, based on an entirely different base set of substances, or at the very least have evolved past sending or listening to things as primitive as radio signals.

Hell, if you hit the reset button on Earth the random infinite series of events might not even result in Humans evolving to the advanced civilization and instead it might be dinosaur based sentience. And whatever evolved might have invented an entirely different line of technology and never used radio as a means of communication.

[noxiousdog]

Regardless, count me as firmly in the, if there were intelligent life, we would have seen it camp.

I totally agree. We've spent a tiny fraction of our history examining a vanishingly small fraction of the universe will exceptionally rudimentary methods for detecting intelligent life.

If that isn't enough to locate intelligent life in the universe, I don't know what is!

So, we can detect the chemical composition of planents, but can't see any sign of leaking 'artificial' energy anywhere in the galaxy? It would take a tiny time frame to colonize the galaxy on the cosmic scale.

Outside the galaxy, sure, that's probable, I guess, but inside I think we would have run in to someone, or we would see an energy signature. I havent heard a convincing argument that multiple civilizations would be able to cloak themselves. Well, I guess if they dyson sphered our entire solar system. But I find that less likely than intersteller civilizations are darn near impossible. All it takes is a super volcano or an asteroid to wipe us out. Perhaps unstable climate.

I certainly can see the possibilty of artificial life through the galaxy, but biological civilizations are tough for me to rationalize.




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[Kraken]

Regardless, count me as firmly in the, if there were intelligent life, we would have seen it camp.

I totally agree. We've spent a tiny fraction of our history examining a vanishingly small fraction of the universe will exceptionally rudimentary methods for detecting intelligent life.

If that isn't enough to locate intelligent life in the universe, I don't know what is!

I agree with RM9's sarcasm.

Ditto. I understand the statistical argument that if there are a mind-boggling number of habitable (by our standards) planets out there, and even the tiniest fraction have sentient life, then the galaxy should be infested. But...

And whatever evolved might have invented an entirely different line of technology and never used radio as a means of communication.

...this. I can readily believe that the technological focus and outward-looking curiosity that underlie our civilization are peculiar to our monkey brains, and possibly highly uncommon among sentient creatures. If there are other mechanically inclined, communicative, expansionist creatures out there they might remain invisible to our rudimentary detective work for quite a long time.

[tripcrow]

I think you’re looking at it from the wrong perspective. The question isn’t the so easily answered quandary of why haven’t we found them. The question is with all the possibilities over the last few billions of years why haven’t they found earth or us? Or if they have why have they moved on without letting us know they exist? It is sorta like the same rational question that if there is a God why doesn’t the real one reveal himself and his wishes in an indisputable manner every year or decade or century. The only answer the Bible gives that I know of is the unreasonable reply that we have some questionable old writings from some long dead Jewish prophets and that should be enough.

[Kraken]

I think you’re looking at it from the wrong perspective. The question isn’t the so easily answered quandary of why haven’t we found them. The question is with all the possibilities over the last few billions of years why haven’t they found earth or us? Or if they have why have they moved on without letting us know they exist? It is sorta like the same rational question that if there is a God why doesn’t the real one reveal himself and his wishes in an indisputable manner every year or decade or century. The only answer the Bible gives that I know of is the unreasonable reply that we have some questionable old writings from some long dead Jewish prophets and that should be enough.

First, you're still assuming that they would be outward-looking and interested in traveling, and then have the technology to do it. Very human-centric viewpoint.

Second, "Us" have only even remotely existed for 2 million years, been sentient for a couple hundred thousand, been civilized for 10,000-ish, and been electromagnetically active for a century. Not exactly attention-getting among all those billions of hypothetically interesting worlds.

Third, there's a tiny chance that they left behind signs that we haven't found or interpreted yet. That's farfetched, but not much more so than spacefaring aliens dropping by in the first place.

[tripcrow]

I do not see it as a humanistic viewpoint. Evolution was going on long before humans. So don’t those answers require the belief that the laws of evolution, roughly as we know them, are at the least very unique to this planet? Much more far-fetched an idea than spacefaring aliens?

Edit: How many common advanced lifeforms do not expand to fill all suitable habitat?

[noxiousdog]

First, you're still assuming that they would be outward-looking and interested in traveling, and then have the technology to do it. Very human-centric viewpoint.

That's the wrong way to look at it. In your scenario, it's not that they would have to be outward looking and travelling, it's that ALL of them would have to not have that characteristic.

It only takes one civilization to colonize the galaxy and they can do it in a very short time frame.

[msduncan]

It only takes one civilization to colonize the galaxy and they can do it in a very short time frame.

Assuming they have conquered the great obstacle of distance and how to develop technologies to bridge that distance quickly.

My entire point is that technologies developed on alien planets by life perhaps not even carbon based would be so different from one another that we might not even HEAR each other.

It might be like a blind person trying to communicate with a deaf person across Central Park.

[RunningMn9]

So, we can detect the chemical composition of planents, but can't see any sign of leaking 'artificial' energy anywhere in the galaxy? It would take a tiny time frame to colonize the galaxy on the cosmic scale.

A) We're only looking for the signs of life that we present to the universe.

B) We're only looking for these signs in a very limited part of the sky.

C) We're only looking for signals that accidentally crossed our path - at the precise moment that we were looking for them.

And for most of our planetary detection methods, we can't detect the chemical composition of planets. We simply infer their presence by the wobble they impart to their star, or to the light that they block when they transit. Neither provides the chemical composition of the planet.

It would take a tiny time frame to colonize the galaxy? You just made that up out of nothing. We don't even know that its possible to colonize even a single exoplanet.

[YellowKing]

Yikes, MSD and RunningMn9 (and me) all agreeing in the same thread. Who would have thought it would be aliens that brought us all back together?

Our search for extraterrestrial life to this point is like walking to the end of your driveway every day for a year, then categorically proclaiming that giraffes do not exist because in 365 days you've never witnessed one in your yard.

Besides the obvious elements of the analogy (the short distance searched, the short time searched), there is the fact that the giraffe doesn't care that we are searching for it, nor is it actively searching for us. This I think is the critical element - there is no possible way we can comprehend alien intelligence without cobbling it together from earth-centric intelligence. Thus any time we try to predict what aliens may or may not do we are starting our argument with a flawed premise.

To take the giraffe analogy one step further, there is the very real possibility that we think we're looking for giraffes, but we're actually looking for dinosaurs that have been dead and buried for millions of years. Or that we're actually looking for giraffes that will be born 3000 years in the future. Doesn't mean that they didn't (or won't) exist....but we have zero chance of finding them in our driveway.

The unfortunate outcome of all this is I think that it is highly likely we will never truly know one way or the other, just as it is highly likely we will never know the true origin of the universe or what lies outside the observable universe. It will remain a frustratingly out of reach mystery.

[noxiousdog]

It would take a tiny time frame to colonize the galaxy? You just made that up out of nothing. We don't even know that its possible to colonize even a single exoplanet.

The galaxy is only 100,000 light years across. Put in any fairly reasonable variables for spread and speed and you can see it doesnt take long in the cosmic sense. Measured in human lifetimes? Sure. But we arent talking about human lifetimes.



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[Kraken]

I do not see it as a humanistic viewpoint. Evolution was going on long before humans. So don’t those answers require the belief that the laws of evolution, roughly as we know them, are at the least very unique to this planet? Much more far-fetched an idea than spacefaring aliens?

Edit: How many common advanced lifeforms do not expand to fill all suitable habitat?

The "laws of evolution" took 4.5 billion years to produce one self-aware species here, so sentience looks like more of an aberration than an inevitability. The jury is out on whether it's a successful survival strategy. So far, so good, but we're still a young species and there's no shortage of people here who are sure that we're doomed.

The only advanced lifeform with which we're familiar shows very little enthusiasm for leaving its home planet. I would like to believe that a human diaspora is inevitable, but that's based more on faith than on evidence.

they can do it in a very short time frame.

At sublight speeds with short lifespans? Your definition of "very short" must be different from mine. Here's an enjoyable look at space travel times based on known propulsion methods. The quickest trip to Proxima Centauri based on actual spacecraft would take 19,000 years. The quickest trip based on theoretical (nonfictional) propulsion? 85 years. Multiply those number by five to reach the nearest star that might have habitable planets (Gliese).

You're going to need either much longer lifespans or much faster spacecraft. Neither of which is impossible, of course, but you have no basis for presuming them.

[noxiousdog]

At sublight speeds with short lifespans? Your definition of "very short" must be different from mine. Here's an enjoyable look at space travel times based on known propulsion methods. The quickest trip to Proxima Centauri based on actual spacecraft would take 19,000 years. The quickest trip based on theoretical (nonfictional) propulsion? 85 years. Multiply those number by five to reach the nearest star that might have habitable planets (Gliese).

You're going to need either much longer lifespans or much faster spacecraft. Neither of which is impossible, of course, but you have no basis for presuming them.

Why would you limit yourself to a human timeframe? Our technology will have colony ships available within a few hundred years. Will you be able to set off and colonize a planet for your kids to live on? No way. They'd be generational ships.

But people would sign up. Hell, they'd sign up today. I'd be one of them.

And 19,000 years or 100,000 years is a blink of an eye in cosmology. We put 6 billion people on the earth in less than 10,000 years after the invention of agriculture.

[Smoove_B]

If I had to guess, I'm feeling that there is intelligent life out there and it is way more advanced than we are. Additionally, I'm going to assume they've checked in on us and then slowly backed out of the solar system. And honestly, could you blame them?

[RunningMn9]

The galaxy is only 100,000 light years across. Put in any fairly reasonable variables for spread and speed and you can see it doesnt take long in the cosmic sense. Measured in human lifetimes? Sure. But we arent talking about human lifetimes.

spread = 0
speed = 0

How long does it take then?

[noxiousdog]

The galaxy is only 100,000 light years across. Put in any fairly reasonable variables for spread and speed and you can see it doesnt take long in the cosmic sense. Measured in human lifetimes? Sure. But we arent talking about human lifetimes.

spread = 0
speed = 0

How long does it take then?

Why would you think that ZERO civilizations would have any interest in colonization? It only takes 1. Just like we had thousands of civilizations that were living quite well, it only took one to take over the planet (or 3 depending on how you look at it, but any of the 3 would have done it).

Likewise, it only takes 1 to take over the galaxy.

[Kraken]

Why would you limit yourself to a human timeframe?

Because it's the only hard data that we have. Speculating beyond that is fun and interesting, but the chain of assumptions necessary for a Fermi Paradoxical pan-galactic civilization (from the nature of intelligence to its motivation and capabilities) are not supported by the very limited facts that we have.

[noxiousdog]

Why would you limit yourself to a human timeframe?

Because it's the only hard data that we have. Speculating beyond that is fun and interesting, but the chain of assumptions necessary for a Fermi Paradoxical pan-galactic civilization (from the nature of intelligence to its motivation and capabilities) are not supported by the very limited facts that we have.

Seriously? We're postulating that civilization could cloak all radiant energy, but not that they'd choose to have generational colony ships?

[RunningMn9]

Why would you think that ZERO civilizations would have any interest in colonization? It only takes 1. Just like we had thousands of civilizations that were living quite well, it only took one to take over the planet (or 3 depending on how you look at it, but any of the 3 would have done it).

Likewise, it only takes 1 to take over the galaxy.

I don't know that there are any other civilizations out there. Civilization is a human construct. And we show no signs of being interested in, or having the capability to, colonize the galaxy.

We can't even get behind sending a handful of humans to Mars.

There is no argument that there are other forms of intelligent life on earth. How close are cetaceans to colonizing the galaxy? How about cephalopods? A wholly different kind of smart. Do they have the desire to conquer the galaxy?

It's taken our planet 4.5 billion years to produce 7 billion humans. How many humans do you think it would take to colonize 10s of billions of other planets? Who would pay for that operation?

[Kraken]

Why would you limit yourself to a human timeframe?

Because it's the only hard data that we have. Speculating beyond that is fun and interesting, but the chain of assumptions necessary for a Fermi Paradoxical pan-galactic civilization (from the nature of intelligence to its motivation and capabilities) are not supported by the very limited facts that we have.

Seriously? We're postulating that civilization could cloak all radiant energy, but not that they'd choose to have generational colony ships?

Not my postulate. It's entirely plausible that a human-like civilization could colonize its own solar system, and even neighboring stars, without drawing our notice. Absence of evidence is not evidence of absence.

I'm still skeptical that an alien intelligence would naturally be technological and expansionist and "civilized" just because we are. The universe could be overflowing with sentient beings that have no affinity for toolmaking and are quite happy right where they are. What exactly are you asserting?