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have they found anything?

amb said:
Out of the millions of lifeforms that have evolved on the Earth, only homo sapiens has developed intelligence enough to ponder these questions.
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What about Homo Neanderthalis? Or are you refering to the entire genus of Homo?

And what do you know of the thoughts of other species? They may not have the technology, but do they have the philosophy? Just a thought to ponder outside our humancentric point of view. :)
 
amb said:
but animal life takes on the average at least 4.5 billion years to evolve from nothing, on a Earth like planet that is at the right distance from it's sun like star at the right distance from the center of it's galaxy,ect, ect.
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Really, the fossil record would dissagree with you on the first statement. Not sure about the start, but that would be (according to all the latest theories) about 1 billion years after the formation of the planet. Complex multicellular life took about a total of about 3 billion years. But hey, it's like government accounting, what's a billion here or there? :p

As for the Earth conditions, you are again falling victim to our one datapoint. Who says those are requirements? For life like us, yes, but evolution is very adaptible, who says that something else couldn't adapt to different conditions? We can't say one way or another.

Even the "right distance from the center" argument is pretty weak... I would GUESS that as long as it isn't IN the center, anywhere in a galaxy could have quite a good chance.
 
amb said:
There just has not been enough time for billions of intelligent species to have evolved throughout the whole universe.
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Sure there has. There's been enough time for it to happen here. More time has not passed here than anywhere else in the universe.

This is surely the weakest argument you've put forth yet.
 
JoeTheJuggler said:
I don't think there's evidence for that claim either. On Earth, plenty of life has existed many many times longer than intelligent life (defined as technology-using intelligence). The oldest known life forms (archaebacteria) are still the most abundant and ubiquitous form of life on Earth. Even among more complex life forms, the dinosaurs, for example, existed a great deal longer than humans have so far.

Most of the lineages of life on Earth thrived without anything like the kind of intelligence we're talking about.
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amb said:
Out of the millions of lifeforms that have evolved on the Earth, only homo sapiens has developed intelligence enough to ponder these questions.
All other lifeforms seem to be doing just fine with their limited intelligence.
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I think you both missed my point. And going back over it, it seems a little strong-anthropic for it to be an actual description of what I really think.

I'll have to think about this a little more.
 
LarianLeQuella said:
What about Homo Neanderthalis? Or are you refering to the entire genus of Homo?

And what do you know of the thoughts of other species? They may not have the technology, but do they have the philosophy? Just a thought to ponder outside our humancentric point of view. :)
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Apart from whales and dolphins, or is that the same species. No other animal seems to have much intellect. At least, none to start a civilization.

LarianLeQuella said:
Really, the fossil record would dissagree with you on the first statement. Not sure about the start, but that would be (according to all the latest theories) about 1 billion years after the formation of the planet. Complex multicellular life took about a total of about 3 billion years. But hey, it's like government accounting, what's a billion here or there? :p

As for the Earth conditions, you are again falling victim to our one datapoint. Who says those are requirements? For life like us, yes, but evolution is very adaptible, who says that something else couldn't adapt to different conditions? We can't say one way or another.

Even the "right distance from the center" argument is pretty weak... I would GUESS that as long as it isn't IN the center, anywhere in a galaxy could have quite a good chance.
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Our solar system is in the habital zone of the galaxy. Too close to the center, we could not possibly exist as the radiation and ultra violet light would render any planet sterile. To far from the center, and the elements that make life possible diminish to practically zero.

JoeTheJuggler said:
Sure there has. There's been enough time for it to happen here. More time has not passed here than anywhere else in the universe.

This is surely the weakest argument you've put forth yet.
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If the universe is around 13.7 billion years old, and Earth life started around 4 billion years ago that leaves around 9 billion years for the first and perhaps even second generation stars to produce and spew the vital elements into the vastness of expanding space to produce Earth like planets and the very elements to produce life.
A question has to be asked, how long does a nebula take to became a galaxy, how long after that does it take to produce a solar system and Earth like planets and moons?
 
amb said:
Apart from whales and dolphins, or is that the same species. No other animal seems to have much intellect. At least, none to start a civilization.
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Did you seriously just say that whales and dolphins are the same species?
The blue whale and the humpback whale are two different species, but you think that both are the same species as a spinner dolphin?
Seriously?

As to other animals forming civilizations, go back a few million years and see if you would predict us forming a civilization.
Someone else pointed out other intelligent species in the genus homo. The fact that they are extinct now doesn't mean they never existed.

Our solar system is in the habital zone of the galaxy. Too close to the center, we could not possibly exist as the radiation and ultra violet light would render any planet sterile. To far from the center, and the elements that make life possible diminish to practically zero.
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How close is too close? How far is too far? How many stars exist in that area, and how did you make your determinations?


If the universe is around 13.7 billion years old, and Earth life started around 4 billion years ago that leaves around 9 billion years for the first and perhaps even second generation stars to produce and spew the vital elements into the vastness of expanding space to produce Earth like planets and the very elements to produce life.
A question has to be asked, how long does a nebula take to became a galaxy, how long after that does it take to produce a solar system and Earth like planets and moons?
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Does it matter? How many billions of such solar systems were produced within the many billions of years window that we're talking about?
I'll give you a hint: a whole lot.
 
amb said:
Our solar system is in the habital zone of the galaxy. Too close to the center, we could not possibly exist as the radiation and ultra violet light would render any planet sterile. To far from the center, and the elements that make life possible diminish to practically zero.
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You made this argument before, and it doesn't hold up. There is no dearth of heavier elements further out, and you don't know that further in radiation would preclude life.

I was just re-reading Asimov's Night Fall. (Sci-fi story about a civilization in a star cluster, who only experience a dark sky once in some thousands of years.) Here they're speculating on life in a much simpler system with a planet revolving around a single star:
"Of course," continued Beenay, "there's the catch that life would be impossible on such a planet. It wouldn't get enough heat and light, and if it rotated, there would be total Darkness half of each day. You couldn't expect life--which is fundamentally dependent upon light--to develop under those circumstances."
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If the universe is around 13.7 billion years old, and Earth life started around 4 billion years ago that leaves around 9 billion years for the first and perhaps even second generation stars to produce and spew the vital elements into the vastness of expanding space to produce Earth like planets and the very elements to produce life.
A question has to be asked, how long does a nebula take to became a galaxy, how long after that does it take to produce a solar system and Earth like planets and moons?
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The answer is, less time than there has been.
Again, this argument is weak. You're trying to say that there hasn't been enough time for an intelligent civilization to arise in the universe, yet here we are.

So then you're trying to argue that there hasn't been enough time anywhere else in the universe except here, even though, as I just said, more time has not passed here than elsewhere in the universe. What makes us unique? We are not unique temporally, as you seem to suggest.

How could there be enough time here, but not enough time anywhere else?
 
Speaking of time. . . one of the prerequisites to life mentioned by the Rare Earth theory is a gas giant like Jupiter to help vacuum up debris and protect the Earth-like planet from more frequent meteor strikes.

(I suppose this is based on the observation that there's virtually no rocky debris in our solar system between the Earth and Jupiter??? Asteroid belt?)

As it is, we get belted with a big hunk of rock about once every 50 million years. Big enough to punch the ecological re-set button and give another kind of animal a shot at being top dog. You're claiming that nearly 4 billion years is a requirement for a tech-using intelligent civilization to arise. I pointed out earlier, that you could have this speculation all wrong. It could be that if the Earth got belted hard every 25 million years, that a tech-using civilization would have come up a lot sooner. (And perhaps in that time span developed the technology to protect itself from a collision.) In other words, more frequent resets might result in more chances of intelligence arising, and the big collision could be another source of selection (that more quickly wipes out forms that don't get technology--at least quickly enough).

Again, the point here is that we don't know. So claiming that any of these things are prerequisite to higher life is just speculation. I can speculate the exact opposite. It could be that the Earth is 100 million years behind the average in terms of how long it took for a tech-intelligence to arise.
 
The first sentence on the sample page of the book you linked to says that the Rare Earth Hypothesis is an "unproven supposition". I totally agree. That's why my speculation on the requirements for higher life forms is just as valid.

It also claims the hypothesis is testable. It says there are two kinds of tests--one is by finding microbial life (using landers that test for the presence of microbes within our solar system) and the other is by searching for evidence of ET intelligence.

I don't think either of these are very conclusive tests of the Rare Earth Hypothesis.

In the first type, either positive or negative results would be compatible with it and also with the hypothesis that higher life forms are relatively common. (Recall everything I've been saying in this thread about the problem with relative terms like "rare" or "common". At this point, you've asserted that "rare" means that we are unique in our galaxy, so let's assume that's what it means here.)

For the second type, both hypotheses are consistent with not encountering any evidence of ET intelligence. If we did find the needle in the haystack, it would disprove the Rare Earth Hypothesis, but there is no test where not finding ET intelligence disproves that it is relatively common. (Again, ET intelligence can be relatively common--like much more frequent than one per galaxy or a dozen in the universe--and we'd still be extremely unlikely ever to encounter evidence of another one.)

It would be like me testing the hypothesis that there are no dogs anywhere in North America by an exhaustive search for evidence in my back yard only. If I don't find evidence of a dog in my backyard, it's preposterous for me to consider that support for my hypothesis that there are no dogs anywhere in North America. Not finding evidence of a dog in my back yard is consistent with the Rare Dog Hypothesis and with the hypothesis that there are a great many dogs in North America.
 
Another way of saying it: if the null hypothesis to the Rare Earth Hypothesis is that ET intelligence is relatively common (much more than 1 per galaxy or 12 in the entire universe), there is no test short of an exhaustive, close-up search (our own civilization is not detectable with current technology beyond our solar system) of the entire universe that allows you to reject the null hypothesis.

Without FTL travel, that exhaustive search is impossible.
 
On the bottom of page 245 of the book sample is this sentence:

An alien astronomer, viewing Earth from a great distance, could detect the presence of life on the planet with comparative ease.
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That's just a false statement.

We've had a tough enough time even detecting extra solar planets in our immediate vicinity. We've had to use clever techniques and expensive equipment, and what we can even detect much less "view" is very limited. (See the image in post #288 of this thread.) An alien astronomer couldn't even view the Earth from a great distance, much less view signs of life or evidence of an intelligent civilization--unless you're assuming technology more advanced than ours or such abundant wealth that anything that is even technologically possible would be something easy to do.

Based on the sample you linked to, I'm unimpressed with the book.
 
Of course you are not impressed by the book. You are starting from a completely different belief, and have shut your mind to anything that differs from your preconceived ideas.
That idea, as any other idea has to start with an open mind, as I did.
 
amb said:
The reason I believe we may be one of the first intelligence in the cosmos is because the first generation of stars had not yet produced the carbon and other elements necessary for life and planets to form.
Carbon and all other elements is spewed into space by a star going supernova. The carbon is produced in the core of a star. Super massive stars have very short lifespans that still take around 1-5 billion years to exhaust their hydrogen supply. Our universe is around 13.7 billion years old. In other words, second and third generation stars were only able to form after the first generation stars became extinct. There has been only enough time for one or a dozen other civilazations in the cosmos at most seeing that life took around 4.5 billion years to reach the stage we are at.
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No, SuperGiantsWP live much shorter lives than that:

"Because of their extreme masses they have short lifespans of 30 million years down to a few hundred thousand years (by the equation M - 2.5 × 1010 where M = mass in sols)[1]. They are mainly observed in young galactic structures such as open clusters, the arms of spiral galaxies, and in irregular galaxies. They are less abundant in spiral galaxy bulges, and are rarely observed in elliptical galaxies, or globular clusters, which are believed to be composed of old stars."
 
amb said:
Of course you are not impressed by the book. You are starting from a completely different belief, and have shut your mind to anything that differs from your preconceived ideas.
That idea, as any other idea has to start with an open mind, as I did.
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HAH!

"You're just CLOSE MINDED!"

What every Bigfoot, religious freak, New Age whacko uses on a daily basis when meeting a skeptic.
 
amb said:
Of course you are not impressed by the book. You are starting from a completely different belief, and have shut your mind to anything that differs from your preconceived ideas.
That idea, as any other idea has to start with an open mind, as I did.
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No. You're wrong. I'm unimpressed with the book because it makes statements like this one:

An alien astronomer, viewing Earth from a great distance, could detect the presence of life on the planet with comparative ease.
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Your close-mindedness is evident from the fact that you repeat arguments that have been debunked (there's not enough heavy-elements elsewhere in the galaxy, for example).
 
Now, do you care to address the issue of how there was enough time for complex life to arise on Earth but not enough time anywhere else in the galaxy?
 
For the record, my position on ET intelligence is that we don't know. (Exactly what Carl Sagan said in that quote I cited earlier.)

I reject the claim that we are unique in the galaxy. I've shown why. You're making a claim you can't support with evidence. All you've got is speculation (or "unproven presumptions").
 
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