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Rare Earth
But expensive monitoring equipment which can confirm the calculation does not always exist, and hence in some fields, our entire knowledge is based on back-of-the-envelope calculations and rough estimates.
Take, for example, the following question: "How many intelligent civilizations, capable of radio communications, currently exist in the Milky Way galaxy?". The worthwhileness of search projects (such as SETI) is closely related to the answer to this question. The number of positively known civilizations is exactly one: the human civilization. And yet, many scientists believe, or at least believed until recently, that the actual number is far, far higher.
This belief was based on various estimates, such as the calculation proposed by Frank Drake, now known as "The Drake Equation." This equation was popularized in Carl Sagan's remarkable TV series, "Cosmos". Sagan himself believed the calculation's result, and was one of the founders of SETI.
Drake's equation is easy to understand. Take the number of stars in the galaxy (about 200 to 300 billion, based on generally accepted estimates), and multiply it by: the percentage of stars that are similar to our Sun in the energy output and stability; the percentage of stars that have planets (since not every star has any); the percentage of planets orbiting their star in a proper distance (so they could hold liquid water, a necessity for maintaining life); the percentage of planets with liquid water on which life actually evolved; and finally, the percentage of life-bearing planets in which intelligent civilizations (i.e., those that can communicate by radio) eventually came to be. All in all, there are five or six factors in this product.
(Note: In my own copy of the book (2nd impression), page 267 states that "a good estimate for the number of stars in our galaxy [is] between 200 and 300 million" - one letter misspelled, and wrong by three orders of magnitude. I do hope the authors' actual calculations were based on the correct value.)
But what values should be used for the various percentages? Drake (and Sagan) chose what they considered to be a conservative approach, and estimated that only about 1 in 10 stars has any planets; only 1 in 10 planets is in the proper orbit, and so forth. Despite the conservative approach, the results were encouraging, indicating that there are thousands of intelligent civilizations in the Milky Way, and probably millions of them in the whole universe. Thus they concluded that there is intelligent life out there, in all likelihood; now we only have to look for it.
In their book Rare Earth, published by Copernicus Press in 2000, Peter Ward and Donald Brownlee point at Drake's (and other physicists') mistakes in a long and depressing discussion, a discussion that took the wind out of more than one SF author's sail.
The book presents what the authors call "the rare Earth hypothesis": simple (bacterial) life is very common in the universe; complex life (multi-cellular life forms, or animals -- let alone intelligent life) is very rare. The first part of the hypothesis is easy to understand, and few scientists will argue with it: indications of simple life were already discovered on rocks originating on Mars, and even here on Earth in conditions that were, until recently, considered completely hostile to life (such as temperatures higher than 100 degrees Celsius, in which 'extremophile' bacteria were found to exist). The second part is the interesting one, and it suggests that the existence of simple life does not necessarily lead to the evolutionary development of complex life, for any number of reasons.
Drake's mistake was basically in the assumption that all it takes for a planet to develop life is being in the proper distance from a proper star. The truth, Ward and Brownlee suggest, is that we have to look at each and every attribute of Earth, and re-estimate its importance for supporting life. Drake's equation is a statistical calculation, but with no other example for life, we're doing statistics with N=1.
Well then, what are the special attributes of Earth that we have to take into account when attempting to run this calculation?
- Proper distance from the star. If a planet orbits its sun too closely or too far away, liquid water would not exist. There isn't much margin for error here: a change of 5 to 15 percent in Earth's distance from the Sun would lead to the freezing, or boiling, of all water on Earth.
- Proper distance from the center of the galaxy. The density of stars near the center of the galaxy is so high, that the amount of cosmic radiation in that area would prevent the development of life.
- A star of a proper mass. A too-massive star would emit too much ultra-violet energy, preventing the development of life. A star that is too small would require the planet to be closer to it (in order to maintain liquid water). But such a close distance would result in tidal locking (where one face of the planet constantly faces the star, and the other always remains dark -- as with the moon in its orbit around Earth). In this case one side becomes too hot, the other too cold, and the planet's atmosphere escapes.
- A proper mass. A planet that is too small will not be able to maintain any atmosphere. A planet that is too massive would attract a larger number of asteroids, increasing the chances of life-destroying cataclysms.
- Oceans. The ability to maintain liquid water does not automatically imply that there will be any on the planet's surface. It looks like Earth acquired its own water from asteroids made of ice that crashed here billions of years ago. On the other hand, too much water (i.e., a planet with little or no land) will lead to an unstable atmosphere, unfit for maintaining life.
- A constant energy output from the star. If the star's energy output suddenly decreases, even for a relatively short while, all the water on the planet would freeze. This situation is irreversible, since when the star resumes its normal energy output, the planet's now-white surface will reflect most of this energy, and the ice will never melt. Conversely, if the stars energy output increases for a short while, all the oceans will evaporate and the result would be an irreversible greenhouse-effect, preventing the oceans from reforming.
- Successful evolution. Even if all of these conditions hold, and simple life evolves (which probably happens even if some of these conditions aren't met), this still does not imply that the result is animal (multi-cellular) life. The evolution of life on Earth included some surprising leaps; two worth mentioning are the move from simple, single-cellular life to cells which contain internal organs, and the appearance of calcium-based skeletons. It appears like the first of these leaps took more time than the evolution from complex single-celled life to full-blown humans.
- Avoiding disasters. Any number of disasters can lead to the complete extinction of all life on a planet. This include the supernova of a nearby star; a massive asteroid impact (like the one that probably caused the extinction of dinosaurs, and 70% of all other life-forms at the time); drastic changes of climate; and so on.
There are also a few attributes that seem, at first, to be completely unrelated to life and not required for its development. Ward and Brownlee argue strongly for the importance of the following attributes:
- The existence of a Jupiter-like planet in the system. Apparently, Jupiter's large mass attracted many of the asteroids that would have otherwise hit Earth. Could life evolve in a system with no Jovian planet? On the other hand, too many Jovian planets, or one that is too large, could lead to a non-stable solar system, sending the smaller planets into the central sun or ejecting them into the cold of space.
- The existence of a large, nearby moon. Luna, Earth's moon, is atypically large and close. Both of Mars's moons, for example, are minor rocks by comparison. What does this have to do with life? Well, it turns out that Luna kept (and still keeps) Earth's tilt stable. Without Luna, the tilt would have changed drastically over time, and no stable climate could exist. If the tilt would have stabilized on a too-large or too-small value, the results could also be disastrous; Earth's tilt is "just right."
- Plate tectonics. Surprisingly enough, it seems like plate tectonics are required for maintaining a stable atmosphere. Plate tectonics play an important role in a complex feedback system (explained in detail in the book) that prevents too many greenhouse gases from existing in the atmosphere. No other planet (except maybe for Jupiter's moon Europa) is known to have plate tectonics. Is this a rare phenomenon, but required for life?
The bottom line is that many additional factors must be added to Drake's equation. One must keep in mind that as any term in such an equation approaches zero, so too does the final product. For most terms, we have no way of reliably estimating their true value, but it seems like at least some of these values are extremely low.
Two important things should be noted about this book. First, about what it does not contain: although I am sure many people will see the Rare Earth Hypothesis as another proof for the existence of a god, this notion of a proof is completely unrelated to the authors' ideas. The hypothesis claims that the conditions for creating complex life are rare; but we know for a fact that at least in one case, all the required conditions were met. Additionally, anyone who insists on taking the ideas of this book as a proof for god's existence will also have to accept the authors' prepositions about the age of the universe, the age of planet Earth, and more importantly, the theory of evolution.
Second, about what the book does contain: the book discusses at length all the issues I've listed above, and more. The problem is that sometimes one gets the feeling that these issues are discussed in too much detail, and the authors tend to repeat themselves, or to delve too deep into some of the less-important aspects of their theory. This is certainly not your common popular-science book; it relies on very up-to-date research results (including some results that were not even published when the book went to press). The writing gets technical on many points in astrophysics, biology, chemistry, and geology (as well as the new field of astrobiology, of course). Over 25 pages of bibliography and references are included.
The theory's weakest point, however, is obvious. The authors admit (after 281 pages of discussion) that their base assumption was that every complex life-form would be similar in many ways to life on Earth: "We assume in this book that animal life will be somehow Earth-like. We take the perhaps jingoistic stance that Earth-life is every-life, that lessons from Earth are not only guides but also rules. We assume that DNA is the only way, rather than only one way" (p. 282).
For me, reading this book was a fascinating and awe-inspiring experience. The most important conclusion (apart from SETI being a huge waste of resources) is an unavoidable cliché, which the authors avoided presenting directly, even though it stares into the reader's face from every page and each paragraph: What we have here is rare, maybe even unique. We should try a little harder to make sure it survives.
Post Scriptum: A news item in the November/December 2001 issue of the Skeptical Inquirer (Vol. 25, No. 6) states that "David Darling, an astronomer who is a critic of the Rare Earth hypothesis, has revealed that one of the strongest influences on the authors, a young [...] astronomer who they acknowledge in their preface 'changed many of our views about planets and habitable zones', has a hidden, Earth-is-unique agenda motivated by strong 'intelligent design' religious views." That astronomer, Guillermo Gonzalez, published several articles in Connections, a quarterly newsletter published by Reasons to Believe, Inc. In one of these articles, co-authored with the creationist scientist Hugh Ross, Gonzalez writes: "The fact that the Sun's location is fine-tuned to permit the possibility of life [...] powerfully suggests divine design."
Darling published these findings, along with a detailed point-by-point scientific critique of the Rare Earth hypothesis, in his book Life Everywhere: The Maverick Science of Astrobiology . Skeptical Inquirer quotes Darling as saying, "What matters is not whether there's anything unusual about the Earth; there's going to be something idiosyncratic about every planet in space. What matters is whether any of Earth's circumstances are not only unusual but also essential for complex life. So far we've seen nothing to suggest there is."
For more about this book, please see this page. For additional book reviews, please visit Tal's bookshelf. You can purchase Rare Earth from bn.com. Want to see your own review here? Just read the book review guidelines, then use Slashdot's handy submission form.
. . . Fermi would be fined for littering. Yet another example of the government oppressing innovation! :)
While using a nuclear device for the search for life elsewhere, we destroy life we already know of here.
What happens when we get acustomed to life elsewhere than?
How about the magnetic field of the earth? Is it known yet whether most other earth-like planets have as intense a magnetic field, or is this property rare as well? I understand that the surface of our planet is shielded from a lot of bad radiation by the magnetic field.
"If you're thinking what I'm thinking, you're right." -
---- El diablo esta en mis pantalones! Mire, mire!
>If a planet orbits its sun too closely or too >far away, liquid water would not exist. There >isn't much margin for error here: a change of 5 >to 15 percent in Earth's distance from the Sun >would lead to the freezing, or boiling, of all >water on Earth.
What about subterranian water?
The ground is constant at about 60 degrees, summer or winter. On a planet with thinner atmosphere, that water might be liquid even when surface water boiled
___
It's the end of my comment as I know it and I feel fine.
should have made a few 'back of the enveloppe' calculations BEFORE sitting a few thousand yards away from a nuclear blast. And then WALKING around the blast area.
This is a sign of high intelligence?
It seems interesting to me that someone critical of this idea uses the fact that they were influenced by the work of a creationist as a method of arguing against them.
What in the world does this have to do with anything?
Isn't this the very worst kind of thinking?
"You're idea can't be correct. There are other people who share this view and I don't agree with other things that they think."
Guilty by association.
Look at the argument for the argument.
Why did that deserve a footnote? I am guessing to fair warn those who might be terrified to find they had been suckered into 'agreeing' with a creationist.
The evolution/creationism debate on many fronts has devolved into a mess. There is a lack of honest exchange in favor of turning one's back to any argument or information.
Not very scientific.
Oh- and I predict this thread for the most part turns into a major conflagration.
.
It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
one of the strongest influences on the authors, a young [...] astronomer who they acknowledge in their preface 'changed many of our views about planets and habitable zones', has a hidden, Earth-is-unique agenda motivated by strong 'intelligent design' religious views.
So what? Science is science, and all that anyone is doing in this subject is educated guesswork. If an author or influence had a 'hidden, Earth-is-random agenda motivated by strong atheistic and humanist views,' would that make his science automatically invalid as well?
Just because someone's science is motivated by pre-existing beliefs doesn't automatically make his science bad. This is just prejudice, end of discussion.
When I saw "Rare Earth", I thought this was an artical about the band!!! =p
If you think most people run SETI to contribute to it's end, your way off. Most people run SETI for the cool factor of techy looking screen saver. It's resource is that it actually looks like you're *doing* something!
Democrats and Republicans only disagree about how to enslave you
... they would be here. (Fermi)
11.0010010000111111011010101000100010000101101000
apart from SETI being a huge waste of resources
I disagree with your statement. The people at Seti are investigating an area of science that simply has a low probability of success in a given lifetime. Does this mean it should not be done? It kinda reminds me of the people who play the lottery, you have a low chance for winning, but hey, if you do, it changes everything. and the longer you stay at it, and the more wavelength-space you cover, the better your chances get. Besides, SETI gets alot of money from private sources these days.
My personal opinion (and thats all this is, MY OPINION) is that SETI is not a waste in time and resources. Are they "LIKELY" to find anything? probably not, but ALOT of people feel that the payout if they do is great enough to continue to do it.
-hommiefro
These are the requirements for life ON EARTH.
One of the things that never ceases to amaze me is the sheer adaptability of life. Who's to say that our way is the only way? who's to say that life must contain water?
The -ONLY- requirement for life is that it must last long enough to reproduce.
In an environment without a moon, so that the planetary tilt shifts and there are more extreme climactic changes, mobility may be more strongly encouraged than it is here, which then might tip the scales in favor of the evolution of intelligence, resulting in an INCREASE of intelligent species.
The long and short? We simply won't know until we find another intelligent species on another planet. And, whatever we find, it will be far stranger than anything we've imagined so far.
I have no problem with your religion until you decide it's reason to deprive others of the truth.
Isn't it possible that life doesn't necessarily have to be water-based, carbon-based, or in need of a sun or planets at all? I forget which novel I read it from (it was years ago), but there was a sci-fi author (Asimov?) who put forth the idea that maybe there could be an intelligent life form that is electro-magnetic based.
Let's expand our thinking and loosen up the requirements a bit!
I went to the city because I wished to live without deliberation.
had a picture of a mushroom cloud, a well-drawn skull and crossbones and the equation
bomb = big
this was later confirmed by small children.
It's depressing that our race still hasn't learnt how to live in peace. The warrior mentality is so deeply buried in our psyche that even the beta-male geeks dream of death and slaughter.
The problem is, these guys are talking about what it takes to creat (Spock voice) "Life As We Know It".
Who is to say there aren't all kinds of life, that can flourish under completely different conditions than what we have here on Earth, or in our solar system?
And I love the "Earth is exactly the way it needs to be to support life on Earth" bit. Well, duh!
I thought that if you were looking at the flash of the explosion he would have been blinded (or at least those convicts the US military got to stare at the flash were , they were testing to see what effect the flash would have on pilots dropping nukes would have)
perl -MIO::Socket -e 'IO::Socket::INET-new(PeerAddr="some.windoze.box:1
- there needs to be a country named "USA"
- there needs to be a state named "Michigan"
- there needs to be a city named "Grand Rapids"
- there needs to be a woman named "Jackie" that
is of Norwegian heritage
- there needs to be a man named "Don" that is of
extremely mixed heritage
- they have to meet and marry
- they have to have two previous children, one
5 1/2 years old and female, one 8 years old and
male
- and then they have to all to take a trip to
a place called "Florida", with its especially
fertile air.
- "grandparents" must live in this place, and
these beings must take care of the aforementioned "kids" for an evening.
- both "Jackie" and "Don" must be in the mood.
and *then* you get me.
Since this is obviously amazing unlikely to ever
occur again, I have therefore proved that no
one in the world exists but me.
Ta-daaaaa!
Me.
(Gosh its lonely)
Well, it depends entirely on what you consider to be "scripture", but assuming that includes the New Testament: ..."
..."
Hebrews 1:2 "...by whom also he made the worlds
Hebrews 11:3 "... understand that the worlds were framed by
The truth is, though, that you don't want to believe it, so you'll discount this evidence too.
This is tripe.
First off, Drake's equation was meant to map our ignorance, not as a serious attempt to enumerate the number of planets with intelegent life, just as if someone asked me how fast a car I'd never seen or heard of was, I might answer "take the distance from where it stops to where it stops and divide by the time it takes" as a (slightly) more informative way of saying "I don't know." Then I suppose these clowns would come along and say "But the driver might have taken side trips! What if he forgot his sun-glasses and had to go back for them? You aren't accounting for acceleration/deceleration time! What about the wind?", etc.
Secondly, "the moon is vital to life" is one of those science fiction plot ideas that predates science fiction. It comes in many forms, but I've never seen one that doesn't beg the question (we couldn't have evolved without the moon because the moon causes X, we are the only example of us we have, and evolved with X; therefore we needed the moon to evolve). It sometimes makes me wonder at the sagacity of whoever coined the term "lunatic."
Third, many of the things they drag in are by no means established (and several are in fact in doubt). For example, we don't know where the Earth got its water, so we can't say if the process is common or not. We have only detected large extra-solar planets because that's all we know how to look for. We don't know that a stable climate is needed for the evolution of complex life (some argue that an unstable climate is required, lest you get stuck at a local addaptive maxima.
Anyway, I could go on, but you get my point: this is tripe.
-- MarkusQ
Ever heard of "Earth Changes" and the cataclysms that have destroyed practically all life on the Earth?
You're right that the Earth magnetic field oscillates. And what happens when a field oscillates? It goes down to zero at one point. Now, when Earth's magnetic field strength goes to zero, all the deadly radiation from the outer space can reach the ground.
I wouldn't want to be around then, 'cause that's the end of the world as we know it.
Of course the military and our government knows all about this and have special bunkers prepared deep underground prepared Utah.
Why? We're not there....
Actually, based on these additional observations, SETI could refine it's search to locations that are MORE like our solar system. Since the authors book is based on making the questions fit the known answer, why not have SETI use that to it's advantage, and look for Earth-like life FIRST?
We can imagine a hell of a lot, but the authors are right, and we KNOW Earth-like life exists. Let's just start looking for the boring (bi-pedal humanoid), before looking for the fantastic (silicon/energy based, whatever you can dream).
"I can't give you a brain, so I'll give you a diploma" - The Great Oz (blatently stolen sig)
That's funny because "Scripture" is responsible for most of these conflicts.
Excessive forking causes un-wanted children.
(Several tens of thousands of years of silence, depending on your bible's timeline)
You do the division.
If even a tiny percentage of stars have planets capable of growing intelligent life, and a tinier fraction of those manage to avoid blowing themselves up long enough to perfect intersteller travel, you should have a galaxy positively swarming with Bug Eyed Monsters. They've had billions of years to cross the interstellar vastness and do the exponential growth thing. So WTF are they? Except for the ravings of that guy in the FBI basement, there's no sign of them.
Fermi's skill is not that unusual. When the slide rule was taught and used, almost anyone could make quick back of envelope calculations. It was an important skill to master because it aided in the use of the slide rule. To get the decimal point right with the slide rule, you had to have an idea of what the magnitude of your result would be. A slide rule will not fix the decimal point for you. That is up to you.
I can quote a bunch of other texts that will say the opposite of what you are trying to claim. So what?
If you're old enough to use a computer, aren't you old enough to no longer need fairy tales?
Or take the first line of the Qur'an: "Glory be to God, the Lord of the Worlds."
It's definitely plural.
Head down, go to sleep to the rhythm of the war drums...
Ancient Sumerians used pictographic writings on tablets. A archaeologist discovered one of these tablets which showed a drawing of our solar system. The thing about it, was, it showed the sun at the center of the universe and also a distant planet that looks like Pluto. Pluto wasn't discovered until around the 1930's, and there were debates on whether the Earth was at the center of the solar system/universe rather than the Sun well after the Sumerian civilization was gone. Sumerians describe Gods coming down to Earth which they called the Annunaki from a planet called Nibiru. The Annunaki created man using Genetic Engineering at a place called E'Den.
Ancient Astronaunts
From Google
It appears the above readers stopped at paragraph one.
Perhaps, if they read to the end of the story they would have found the immense irony and reflection made by the the emphasis stating perhaps "life is much more rare than we once thought, and therefore more precious than we've realized" I think the whole atomic blast opener quite sets into place the idea of realizing that "yeah, gee, perhaps we need to be a bit more careful with this thing called life and be careful we don't destroy it"
Hmm...I think you missed the entire essence of the article. I will be courteous and assume you are just pre-judgmental and did not finish the article lest I must assume you both were just plain stupid "anonymous cowards"
You got to love the postscript.
Some ignorant jackass (and legions like him) imagines a personal affront to his religion (and probably his funding), but lacking any knowledge, abilities, or reason, turns to a personal smear campaign, claiming the authors were influenced, even duped, by a bomb tossing pedophile god worshipper false scientist.
OK, sure, I can buy the argument that throughout time there must be thousands of civilizations in the universe that are capable of radio contact... but that's stretched out over the lifetime of the universe.
Not all civilizations will last forever, not all will go into space and continue propigating, not all have invented their radios just yet. After all, we just celebrated the 100th anniversary of a trans-atlantic transmission...
What if aliens had turned their sattelites on our speck in the sky just before our signals went out in the air... What if they died off millions of years before life started evolving on this planet? What if we're the first life to exist in the universe (not ruling out that others could evolve, just that they haven't yet).
We don't know shit about this, and we won't until our Zefram Cochrane comes along and helps us reach to the other stars.
- passion
The underlying problem with this and many other ET discussions is that they assume all life requires parameters similar to our own. Once the possibility of life taking forms completely alien to our own is accepted almost all current debates on the matter have their scope changed. No longer is it a debate about the existence of complex life, it is a debate about the existance of complex life as we know it.
The circumstances that allow intelligent life to develop are just too unlikely to ever occur. Therefor, I propose that it is just a mistaken assumption to believe that there ever was such a place as Earth... and even if there was, intelligent life never would have developed.
Hmmmm... reading some of the political news, this is probably correct.
Assuming that all the factors line up again (or different factors work out)
AND life reaches multicellular levels
AND eventually sapience
AND they are psychologically enough like us to want to reach out to the universe
AND they are an engineering species (if dolphins eventually reach full sapience, their lack of hands make constructing massive radios a little bit of a trick)
AND they develop a metallurgical technology so they can discover radio waves (a biosciences technology could possibly reach incredible advances without ever discovering radio)
AND they aim the transmitter in the right direction (or build a super massive omni-directional one)
AND they don't give up too soon or start transmitting too late
AND they send a signal we understand as a signal
AND...
I love SETI and I WANT it to succeed, but do I think it will... not so much.
(Several tens of thousands of years of silence, depending on your bible's timeline)
You do the division.
Well, you (and everyone else) seem to think a biblical day is one revolution of the Earth... What if it's a revolution of the Galaxy.. the Universe?
Some people can't "break out of the box", and take different perspectives. Both sides can be right, it just takes a little leveraging, and ego bashing. :)
"I can't give you a brain, so I'll give you a diploma" - The Great Oz (blatently stolen sig)
What many people seem to forget is that that ideas of evolution and creation are not science at all. It can never be proven that the process of evolution worked on some stuff in the proper location, and resulted in what is alive today. Likewise, it can never be proven (scientifically) that creation is the proper explanation. The reason is the same for both (and quite simple): nobody is around now that was alive then. Pure science is based on direct observation. This is a mistake often made by spokesmen for both positions. This is not to say that there is no evidence that can be used in the argument, just that it shouldn't be called science (or a proof).
Quite subtle enough to induce moderation points from the few God-fearing creationists on Slashdot.
But too contrived to show up on the radar of the evolutionists.
I have two ideas regarding this.
First, as a civilization approaches the technological level necessary to travel to the stars, they also have a myriad of opportunities to kill themselves off. I.E. nuclear war, designer viruses etc. As technology increases, (at least here) we are coming to the point where more and more dangerous technology can be used by the single deranged individual.....
If an evolutionary model is used, I think most species would have a crazy or two who might end up causing their own extinction. We are very near this point. Imagine either nanomachines, or plague as the easiest self replicating disaster.
2nd, perhaps other life does exist, but is not motivated by the explore and conquer ideal.
A xenophopic or non-curious species.
Service guarantees Citizenship! Questions Guarantee GITMO.... Amerika Uber Alles!
Hello Yr0,
Thanks you for your interest in a Tasty Beef Jerky recipe. When the poison spitting cobra faces who call themselves moderators stop banning me, I will post my most zesty and flavorful recipe for jerkied beef. Thanks you
RT
Hello, my name is Dan BentlEy.
My father is Jon BentlEy.
We spEll our namE with an E.
To Taco:
"My name is Dan Bentley. You kill my father ('s name). Prepare to die.
I think the quote is "if there were intelegent life on other planets, they would not come here"
as a statment about how horrible our civilization is.
I am the Alpha and the Omega-3
"We assume in this book that animal life will be somehow Earth-like. We take the perhaps jingoistic stance that Earth-life is every-life, that lessons from Earth are not only guides but also rules. We assume that DNA is the only way, rather than only one way" (p. 282).
It's not a bad assumption in my mind. It's hard to think of another form of life without some of our features being as industrial as we are. The human body is well adapted not only to our climate but for creating as well.
While I know it is only a movie, in K-PAX they were discussing why the alian was in the form of a human. The alian responded it was like a drop of water, formed to what was the least resistance. The human form was the best suited for the environment.
I'm firm believer that science is universal, and that for another life to contact us must at least have some means to put together a transistor radio.
-AlPhAbEt
> Gonzalez writes: "The fact that the Sun's location is fine-tuned to permit the possibility of life [...] powerfully suggests divine design."
I can't resist pointing out that if the Sun wasn't in such a state, we wouldn't be here to talk about it.
On the other hand, if the Sun wasn't so tuned, and we WERE here and not all dieing of mass cancers or being frozen/boiled, I'd be much more inclined to believe that maybe there is some divine intervention there.
nowadays, you are lucky to not be SHOT for making an anti-governmental remark.
drake's equation, as summed up in the review, seems awfully earth-centric to me. why, for example, is water or carbon, necessary for life?
(spare me the biochemical arguments -- i'm aware of them)
it appears that we look around our world and assume the conditions of our environment are essential for life. but, we have discovered anaerobic life, bacteria that live in undersea hot chemical springs and in the upper atmosphere, etc. what's to say "life" can't evolve in environments that are inhospital to earth life?
perhaps there's a conciousness out there in space thinking, "life on earth? with all that oxygen and carbon -- no way!"
The fact that the enviroment we're living in is so rare in the universe is not surprising. If there were no such environment nobody could think about it ...
with these equations is that, although they are an esimated guess, there are far too many unknowns.
Until we find *some* kind of life *somewhere* else other than earth, we simply do not have anything to really go on to build statistics.
It's like, say I bring you over to my computer, tell you to hit enter, and then the computer shows you a number on the screen.
I tell you that this program follows a pattern, (not random) and that the numbers it produces are between one and a hundred billion.
Then I ask you what the probability of the same number coming up again is.
You have nothing to go on.
I believe the original Hebrew translates more literally to "lands", not "worlds." Thus the verses you quote are not referring to other planets. Think about this, other planets would be a pretty big deal. Wouldn't they be mentioned very prominently? The fact that they are not is strong evidence that they don't exist.
When I'm not so human first in my thinking I also use the following explination:
There are two intelligant civializations in the universe. (this expands to more, but not many) The other is many millions (maybe billion) lihgt years away. We can turn our telescopes on them, but the problem is they were intelligent millinos of years ago. Likewise they are turning their insterments on us, and the insterments would detect us, but we were not emmiting intelligent signals back when they would have had to leave earth to arrive now.
By the time we detect each other, we are both on the decline, by the time we get a response out, both are dead. And worse yet, because we are so far apart we can never impart useful information to each other. They might look on Fermet's last theorm as a child's exercise, and they might hear about it in their first decoded transmission. They can send a response right away, but it doesn't help, they won't get the problem for several million years, and we sovled it already. Likewise we can solve problems that they are interested in and haven't yet, but they will solve them long before we get decode their interest and get a solution back.
The idea that we are the first is certainly interesting, and if you consider the additional requirement for supernovas to explode and litter space with the higher elements (carbon, oxygen, nitrogen, iron etc) then it may well be that we got here pretty much as fast as it can be done.
:)
Give or take a few 10s of millions of years, that is.
And, 10 million years is PLENTY of time for an intelligent species to get smart, get expansive and then vanish. Expand if they can, that is.
We've only had radio for about a century, for instance. Space flight somewhat less. And we have no idea how much wealth it would take to colonise a new world. It may be that, not only are we not rich enough now, we will NEVER be rich enough.
NOW is unique because we are close to our peak population on the planet. It seems likely that the Earth's population will start to decline around the middle of this century. Hence, fewer people to conduct research, generate new ideas, build wealth and get things done.
If it isn't going to happen in the next few centuries (as far as BIG projects go) then it might never get done.
This is the last, and best, renaissance.
Enjoy it.
At the risk of answering a troll, how about Ezekiel?
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
Right, the atheist Joe Stalin used the Bible as his justification to murder 100 million innocent people. Pull the other leg, why don't you. And then Chairman Mao based his bloody Cultural Revolution on Scriptural principles. And then Pol Pot and his benevolent regime. A handful of people get killed in the Inquisition (which was a Catholic thing, not a Christian thing) and you people think you can blame every atrocity in history on the Bible. Well you can't, because 99.9% of them have been atheistic in nature.
Oh please -- I am so glad someone threw in the theological angle on this -- an unproven doctrine upheld by a fervent cult...
Huh. The postscript must have been entirely changed before I read it, as the version that I read makes no smears nor does any name-calling.
Unlike your post.
1) Other life doesn't have to be like us. Just because we haven't seen life based on something else doesn't prove that it cannot exist. Maybe the most common form of life in the universe are hydrogen based blimp's floating in the atmosphere of gas giants around red dwarfs! We simply don't know yet!
2) In regards to the comment about there not being complex life, I suggest the book "Non-Zero" which talks about the concept that once life comes around, it will ALWAYS progress towards more complex lifeforms. (barring cataclysmic events) This is simple darwinism, the first lifeform to innovate will prosper until its prey catches up, ad infinium.
Personally, I like to maintain optimism. For example, I believe that faster-than-light travel (not necessarily "moving" FTL though) are possible simply because the universe would suck if we're confined to one or two planets forever. It may be irrational now, but "scientists" have said things were impossible which are now commonplace.
Travis
Please enligthen me about your novel definition of "evidence".
What you choose to belive is not evidence.
"First lesson," Jon said. "Stick them with the pointy end."
putz -- because a person believes in the Quran it makes them a terrorist?? Love the ugly american angle... did this become an american website -- when did this happen; I was neither frisked nor was my passport requested when I logged on to /.
I personally have always liked the "Foundation" type galaxy that Asimov wrote about - one with billions of inhabitable planets, all uninhabited and just waiting for us to colonize them. If, as this book suggests, it takes a very, very tight set of circumstances for life to evolve, that may be the way the galaxy is.
We can live on a much wider variety of planets than the one we evolved on. We've got at least one (Mars) right here in the solar system that we can adapt to our needs, albeit with a lot of work. Even Venus might be okay with a huge amount of terraforming. To me,that means there is probably at least one marginally livable hunk of rock in just about every star system. Even if it's only 1 in 100, that's a lot of expansion room.
Heck, I hope we ARE the only ones here. I like the idea of all that elbow room.
Serving your airship needs since 1995.
Purely in response to your second point, I'm reminded of Niven's "One Way Street" (I'm surprised no-one else has mentioned it yet). I'll not diminish the story by summarisation, but one of the points made is that without the Terra-Luna system to stir the atmosphere and makes tides, our planet would be a lot more like Venus - covered in clouds and victim of a greenhouse effect to melt lead. Niven's description is wonderfully evocative - "an eternal searing black calm".
Now, whilst I don't take issue with your objection to the 'massive moon vital for life' view, I do think it's important to note that our particular system does seem to be a rather odd freak of fate that has strong bearing on our existance. Perhaps the more correct view would be that a large moon is necessary for Earth-like life to develop. This is, as others have pointed out, rather like evaluating the probability of the factors that led to your own birth (eg, my father dropped a screwdriver on my mother's head - would I be here if he hadn't?).
Personally, while I find the argument fascinating, I consider the implications to be more metaphysical in scope than scientific. This is probably why it attracts so much emotive argument...
|>
Here be Dragons
Let's just assume that a planet just like Earth[TM] is the only way to get intelligent life.
Add all of the extra pessimistic factors described in the article to the Drake equation. Put in reasonable values for everything. If you get an answer greater than one the Fermi Paradox means that finding intelligent life (or it finding you) is still likely, if you manage to keep a civilization around long enough.
I forget who I'm paraphrasing, but I've heard a convincing argument for the absense, or extreme rarity of other intelligent life in our galaxy. It goes something like this:
In 20,000 years, humans have gone from banging rocks together to reaching escape velocity.
Earth has been capable of supporting intelligent life for way longer than 20,000 years, and the galaxy has been around for much longer than Earth.
Even if faster-than-light travel is impossible, at a mere 100,000 light-years across, a single intelligent race around at the time of the dinosaurs could have colonized the whole galaxy many times over by now.
Which sounds the most likely?
a.) Intelligent life is either very rare in our galaxy or unique to Earth, or
b.) Intelligent life is abundant and coincidentally developing at more-or-less the same level everywhere, or
c.) Intelligent life is abundant, but Earth is in the lead development-wise.
Perhaps there is a forth option, but without one, option 'a' is the simplest and , therefore, most likely to be correct.
Some people have a way with words, and some people, um, thingy.
Can you be more specific?
"Huge waste"???
I don't know what the total amount spent on SETI is, but for instance Arecibo's entire annual budget is US$11m (Google tells me). Multiply that by 10, which is probably way too much, and how is that "huge"? It's about what Bill Gates spent decorating his house. It's about what one A-list movie star "earns" in a year. It's trivial. For something with literally cosmic implications to science, philiosphy, religion and EVERYTHING, it's beneath contempt to claim this is something unaffordable, no matter even if these geeks are right and the chance is vanishingly small. Not to look when we have the capability should be a crime against humanity.
Think about this, other planets would be a pretty big deal. Wouldn't they be mentioned very prominently?
God speaking: "Look guys, I love you, but I have 500 billion other Worlds to take care of. I've set the whole planet on 'automatic' so you'll be on your own for most of the time. If something is important, you might have to pray harder than usual to reach me. Other than that, enjoy the ride."
See, that doesn't make a very good religion.
Hey, why haven't WE colonized the galaxy yet? Since we haven't given any indicator that we exist (outside of a 90 light year radius or so, and then only weak ass radio signals), we must therefore not exist.
Fermi was super intelligent in some areas, and dumb as a brick in others (like everyone else). Saying that it ain't there because you haven't found it is silly.
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
I was about 3/4 of the way through writing a new novel when "Rare Earth" came out; since "Rare Earth" contradicted pretty well every premise I'd based on the novel on, I was pretty freaked--until I actually sat down and read through the book. I shouldn't have worried. The basic arguments put forward in "Rare Earth" are each consistent and compelling; the problem is that each challenge to the development of life presented has its own solution(s), which they ignore. For instance, they maintain that plate tectonics is essential for the maintenance of an atmosphere; this is manifestly untrue, because neither Venus nor Mars have plate tectonics, and both planets have atmospheres (albeit unlike our own). In fact, when you examine Venus, it turns out to have something that may fulfil the same role as plate tectonics: "coronae" which are upwellings from inside the planet that form ring-shaped volcanic chains. So an Earth-like planet with coronae is quite conceivable, even likely. The authors of "Rare Earth" argue fallaciously by assuming an exact match to the Earth to be required for life, then running through a laundry-list of reasons why such an exact match is rare. But an exact match isn't required; not even an inexact match. My new novel posits planets in orbit around brown dwarfs (failed stars bigger than Jupiter but smaller than the smallest red dwarf). In researching the book I became convinced that such exotic environments (which may be the rule rather than the exception in our galaxy because brown dwarfs are at least as common as lit stars) are perfectly fine environments for the development of life: for sunlight, substitute infrared radiation and intermittent visible-light flares from the dwarf; for plate tectonics, substitute tidal stretching by the dwarf; for a Jupiter to protect against cometary impacts, substitute a smaller and more impoverished Oort cloud. The list goes on and on--for every supposed "requirement" of the Rare Earth hypothesis, there's at least one, usually many, alternatives.
I typically find it unscientific to attack anyone's work because they have "an agenda". Everyone who publishes these things has "an agenda". Its best to assault them on scientific grounds rather than philosophical. A theory is only as good as the supporting data. Since until recently we didn't even have positive proof other stars had planets, we seem to have a lack of any usable data, save from our own solar system. The planets we have seen around other stars appear to be gas giants (primarily due to physical limitations of our instruments, ain't optical diffraction and photon counting a bitch!). Neither side has room to be taking pot shots, since there assumptions are basically articles of faith (do I discern signs of a new religion here?). I see no reason why life can't be based on silicon or some other materials when a planet orbits a sun with too much UV. It seems to me that critical to the development of life is a photon source with sufficient energy to make chemical reactions occur dependant on the materials available. This reminds me of Sagan's nuclear winter theory, too many unprovable assumptions. It doesn't mean its a bad theory, just unprovable with current knowledge.
His argument was if there were a number of intelligent alien civilizations in our galaxy - then there was a good statistical probability that some would be much more advanced than us. If they colonized the galaxy at moderate sub-light velocities (say 0.1c) then they would have colonized the entire galaxy in about 10^5 years. So if there were many extraterrestrial civilizations intelligent aliens should be here by now (he assumed that UFO phenomena were not produced by aliens).
This stuff is on the web - but I have forgotten the URL. Google "Fermi's question" and you should find it.
Most intellegent species blow themselves up long before they get around to interstellar exploration.
I've seen this on all sides of the debate.
I'm a religious person; I believe in a creator. Does that mean I agree with all the creationist wackos out there who don't know how to do good science? Nope. Does it mean I look skeptically at atheistic scientists who look at something they don't understand, can't explain, and pronounce there must be some mysterious non-divine explanation because they've already decided there's no God? Of course I expect them to back up their science.
Right now science doesn't have good explanations for exactly how macroevolution works. Religion doesn't have good explanations for the apparent age of the universe. Everybody should just fess up and admit they don't know the whole story, quit pushing dogma, and work on finding honest answers.
But hey, I'm religious and therefore biased.
People are never as simple as their stereotypes. This applies equally to Christians, Muslims, and Emacs-lovers.
Even if all the factors were considered using conservative values and the results indicated a "good" chance that other life like ours must exist. This still does not account for time.
Specifically, a question that we can only guess at, what is the average life span of an intelligent species? At what point, due to their own intelligence or an external influence, will an existing intelligent species cease to exist?
Currently we have no idea how long we will be around... until the first global thermal-nuclear war? Until the greenhouse gas effect does cause catastrophe? etc.
There may indeed be intelligent life out there now or in the future. That doesn't mean they or we will be around long enough to find each other.
My second more positive thought to consider:
Let us for a moment consider that the suggested "more complete" equation is correct. This gives us an equation with the following factors:
Now if we use the conservative values suggested (200 billion stars/galaxy and a 1 in 10 chance per factor) we will get the result that each galaxy has 0.002 planets like Earth.
This means that for each 500 galaxies in the universe there will likely be 1 Earth like planet (intelligent? life and all).
This leads to the question: How many galaxies are there in the universe?
--
WasteOfAmmo who can't currently log in due to being at work and forgetting the password! Sigh!
gives an interesting analysis of the belief that organisms increase in complexity. Gould argues that organisms are just as likely to evolve into something more simple as into a more complex organism.
There's strong evidence that the earth was once an iceball yet life not only survived, it had an unprecedent and unmatched explosion of diversity after the Thaw.
The problem with the earlier models is that they only considered the incoming solar radiation and the ice. Shortly after the oceans froze over, the surface temperature near the equator was -50F and stayed there for many thousands of years.
But the earth (and any tectonically active planet) has volcanoes. Volcanoes release greenhouse gases, notably CO. According to one estimate I saw on the Discovery Channel (IIRC), the CO level hit _10%_ and the surface temperature was something like 150F before the ice started to melt. (Remember that the conversion from ice to water takes a *lot* of energy, and there was only poor thermal coupling between the hot atmosphere and frozen ocean.) Once the ice started breaking up, there was a cascade effect that lead to a thousand years of acid rain as the CO was washed out of the atmosphere.
And after the Thaw, we had the Cambrian(?) Explosion, the transition from the simple single-celled organism (the only life that could survive under the shattered sea ice) to multicellular life.
This begs the question - is an "iceball" stage a necessary precondition to multicellular life? If it is, and the fact that most life-bearing planets will have an iceball stage since stars become brighter over their lifetime as main sequence stars, then a key part of their argument is invalid. Life-bearing planets will have ice-ball stages, and multi-cellular life will appear after the Thaw.
As an aside, one thing that's unique about the solar system is the unusually high level of metals for a system of our age. Maybe complex life requires these metals, and we're a few billion years too early.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
The Greek word used here, aion, can be translated 3 ways:
I'm not sure where you are trying to go with this line of argument, since we clearly know that other worlds DO exist (Mercury, Venus, etc...). IN FACT, this means that it would be a very bad thing if scripture definitively said THERE ARE NO OTHER PLANETS since it would be false, and thereby conclusively rule-out divine authorship of the Bible (unless one would want to say that the divine being is a liar, but that's another can of worms).
MarkusQ, big kudos to you for the first correct, appropriate in context, use of "beg the question" I have ever seen on this site. It is misused *vastly* more often than it is used correctly, so it's a relief to see it right for once. Way to go.
Light cup, beer drink, thin so chain, neck turtle fat, man I won't say it again
I know this was not the authors intention, but for me it is another indication for God. Like the BigBang...
The question is: who or what caused the BigBang.
Believing that God made the BigBang is as plausible as any other theorie...
I'd have to be a believer already to even begin to buy the hooey I put up in the previous post.
Bull. Martian tropics can get above freezing in the summer. Mars is 50% further away than Earth.
A star of a proper mass. A too-massive star would emit too much ultra-violet energy, preventing the development of life.
*Our* star emits too much U-V. Did you ever hear of the ozone layer? What did life use for shielding before the you ask? Ocean water blocks U-V.
A proper mass. A planet that is too small will not be able to maintain any atmosphere.
How much smaller? Mars could probably hold a thicker atmosphere than its got, Venus, and Earth sized planet, can hold a much thicker atmosphere than Earths. Smaller planets may actually be better. A bigger problem with small planets is low volcanic activity.
A planet that is too massive would attract a larger number of asteroids, increasing the chances of life-destroying cataclysms. Oceans.
The Earth hasn't experience one life-destroying cataclysm. It seems logical that it would be harder to destroy all life on a larger planet than a smaller one.
The ability to maintain liquid water does not automatically imply that there will be any on the planet's surface. It looks like Earth acquired its own water from asteroids made of ice that crashed here billions of years ago.
There is no evidence that these comets are rare.
On the other hand, too much water (i.e., a planet with little or no land) will lead to an unstable atmosphere, unfit for maintaining life.
How, or do you just mean higher winds? What bearing does this have on life.
A constant energy output from the star. If the star's energy output suddenly decreases, even for a relatively short while, all the water on the planet would freeze. This situation is irreversible, since when the star resumes its normal energy output, the planet's now-white surface will reflect most of this energy, and the ice will never melt.
I suppose this is why the ice ages never reversed. A high C02 atmosphere might negate this argument. The sun has not been consistant in its output, and there is no evidence that stars as constant as the sun are rare.
Successful evolution. Even if all of these conditions hold, and simple life evolves (which probably happens even if some of these conditions aren't met), this still does not imply that the result is animal (multi-cellular) life. The evolution of life on Earth included some surprising leaps; two worth mentioning are the move from simple, single-cellular life to cells which contain internal organs, and the appearance of calcium-based skeletons. It appears like the first of these leaps took more time than the evolution from complex single-celled life to full-blown humans.
The evolution of increased cooperation could be inevitable. There is no evidence that the events mentioned above were random singular events as opposed to the culmination of eons of progressive evolution.
Avoiding disasters. Any number of disasters can lead to the complete extinction of all life on a planet. This include the supernova of a nearby star; a massive asteroid impact (like the one that probably caused the extinction of dinosaurs, and 70% of all other life-forms at the time); drastic changes of climate; and so on.
I'm not sure about the supernova, but everything else you've mentioned here *has happened to Earth*, yet here we are. Not only did life survive, but maybe they are essential to the evolution of complex life.
The existence of a Jupiter-like planet in the system. Apparently, Jupiter's large mass attracted many of the asteroids that would have otherwise hit Earth. Could life evolve in a system with no Jovian planet? On the other hand, too many Jovian planets, or one that is too large, could lead to a non-stable solar system, sending the smaller planets into the central sun or ejecting them into the cold of space.
No evidence that these are rare. Earth has two (is uranus/neptune Jovian?) Jovian neighbors. How many is too many? How many planets have been ejected from our system?
The existence of a large, nearby moon. Luna, Earth's moon, is atypically large and close. Both of Mars's moons, for example, are minor rocks by comparison. What does this have to do with life? Well, it turns out that Luna kept (and still keeps) Earth's tilt stable. Without Luna, the tilt would have changed drastically over time, and no stable climate could exist. If the tilt would have stabilized on a too-large or too-small value, the results could also be disastrous; 1Earth's tilt is "just right."
Earth's moon is atypical. But how does it affect life? It's not plausible that a change in Earth's tilt would wipe out all life, or negate the possiblity of life forming. The Earth has experienced a lot of dramatic climate change, even with the Moon's steadying power. Yet life trucks on.
Plate tectonics. Surprisingly enough, it seems like plate tectonics are required for maintaining a stable atmosphere. Plate tectonics play an important role in a complex feedback system (explained in detail in the book) that prevents too many greenhouse gases from existing in the atmosphere. No other planet (except maybe for Jupiter's moon Europa) is known to have plate tectonics. Is this a rare phenomenon, but required for life?
Interesting idea. Another planet that probably has plate techtonics is Venus. Yet it is loaded with greenhouse gasses. The Earth probably has other mechanism for reducing greenhouse gasses.
Creationist claptrap at its worst.
Play Command HQ online
It's called Trinitite and you can still see some down at the test site at White Sands under a protective enclosure. You can also find some on the ground although it's getting more difficult. They ask you not to pick it up but you still see people doing it. The site is open first Saturday of October/April.
I'm in Wisconsin, the Earth's tilt sucks.
if u don't get it, you've never lived here.
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ahh... you must be one-o-dem bible beatin' holey rollers runnin' 'round with poidnus snakes. This is America, where there's nothing wrong with quoting the Quoran, or praying to Allah... You're part of the problem redneck!
Two important things should be noted about this book. First, about what it does not contain: although I am sure many people will see the Rare Earth Hypothesis as another proof for the superority of the capitalist system, this notion of a proof is completely unrelated to the authors' ideas. The hypothesis claims that the conditions for creating a capitalist system are rare; but we know for a fact that at least in one case, all the required conditions were met. Additionally, anyone who insists on taking the ideas of this book as a proof for the superority of the capitalist system will also have to accept the authors' prepositions that other economic systems may in fact count as complex life, and that the theory of evolution may include the possibilty for other economic systems to evolve.
The Fermi argument is really that if there are lots of planets supporting intelligent life, it is likely that some of them are more advanced than us, and so should have explored further, or at least worked out how to signal us. (The fact that Fermi was mentioned at the beginning of the article was a bonus.)
11.0010010000111111011010101000100010000101101000
Perl is obvious a tool in some hidden agenda Larry Wall is wreaking upon the hacker community because he was influenced by religion.
For instance, the Catholic Encyclopedia has this to say concerning Hebrews:
Another similar document, in discussing the evidence against Pauline authorship, offers the following: "The Greek style is not typical of Pauline abruptness and digressions; it is more classical."If Hebrews was originally written in Hebrew, as you say, then the Greek style should be of little importance.
No mention is given to the original being written in Hebrew. Can you point me to your source?
What if other intelligent species realize it's better to focus on wisdom and living in the moment? I don't think humans are intelligent. Definitely self-centered and egotistic.
The term used in the review was "complex life", but most of you keep using "intelligent life". The former is certainly in existence on Earth, but I think the jury is still out on the latter.
I agree with the idea that Drake's equation is wrong, but not for the reasons stated.
Drake is assuming that all life must evolve on an earthlike planet. Europa-like planets, with a possible liquid ocean, and warmth supplied by the tidal forces of a gas giant, seem much more plausable. (Btw, the book discussed seems to ignore this possibility as well). Jovian planets seem more common then earth-like planets, and some of the reasons the book brings up for the decreased incidence of life don't apply (Jovian planets can be at a distance from the sun where the sun's energy fluctuations wouldn't matter, since the moons are warmed by tidal forces. Of course, in some discovered systems, Jovian planets are rather close to their stars, which means the $64k question for this scenerio is: how many stars have Jovian-type planets with the appropiate moons at the right distance?).
On earth, life took quite some time to jump from sea to land. On a Europian planet, there is no land, but there is another "beach" they can wash against - airless vacuum. I don't see any reason why a creature can't evolve to live in a vacuum, which leads to the idea of a lifeform being able to live in interstellar space. Imagine a creature that is content to drift through space in a dormant state, only "waking up", when its near enough to a star for its version of photosynthesis. Damned if I'd know how such a life could generate intelligence, but if I was a Europan, staring at earth, monkeys making fire wouldn't be an idea I'd come up with. ;)
Of course, we have the Jovian planets themselves, with thick atmospheres, and the chance of liquid water to exist in that atmosphere.
The point of these examples, is that the Drake equation is misleading, making assumptions that might not be true.
Just my $.02
Whenever I remove my tinfoil hat, the cacophony is deafening. Amongst the several societies communicating with me is one that wants to mine our planet for salt, and one that would just like the recipe for Krispy Kreme donuts.
So, obviously, this book is garbage.
C8H10N4O2 | Developer > Code
Read this book back in '99 in astronomy class at CU. Excellent book disputing the claims made by Sagan and the drake equation (cited numerous times by jodie Foster in the movie Contact). It touches on most of the known factors in creating/sustaining a habitable planet. After finishing it however, I am still not convinced that the Drake equation is not valid. There are millions of factors that equate to a hospitable planet for Life As We Know It, BUT we are assuming that life is carbon based (rather than silicon based, which IS possible), and requires the same environmental elements that we do. This may prove to be another case of human ignorance similar to us projecting ourselves at the center of the universe for a good part of the last millenium. This in conjunction with the sheer number of possible "Earth-like" planets out there makes me very optimistic that life IS out there. Europa may contain life (though the issue of whether or not the water beneath the ice of Europa is sterile or not still stands)highlights this possibility. Though this book is excellent, and worth reading, don't drop Drake quite yet.
Right now on a distant planet, someone is writing a book about how life is only possible on a planet that is tidally locked to it's star.
Right now on the moon of a giant planet, someone is writing a book about how life is only possible on moons of giant planets.
As near as I can tell, the author came up with a list of conditions that might (yes, might) have been conducive to the development of intelligent life on earth. Then he jumped to the conclusion that those were the only conditions under which intelligent life is possible.
Seems a bit of a stretch to me.
Support SETI@home
What I find especially troubling here is the implication that since by the author's estimates the odds are low, then the search should be abandoned as a poor use of resources.
Resource allocation has to be balanced against possible return on investment, which in this case is hard to quantify, but possibly huge.
One need to also look at what can be done today at what cost, and what can be done tomorrow at what cost. One can reasonably predict computer price/power ratio to exponentially increase for at least the next 2 decades, if not the next 5 decades. If the computer power needed to reasonably search data (SETI@home aside), won't exist for 5 or 10 years, then plans should be made as to when larger searches should be started, based on when affordable compute time will be available. This is tied up in making best guess estimates on approximate distance to intelligent civilizations, likely broadcast power, distance signal could be detected from, etc...
While there are many factors that can be used to better bound Drakes' equations, has as been pointed out by an earlier poster, one most not assume all factors likely to have helped intelligent life establish here on Earth are required (like the large Moon hypotheses). To add to this, what is not factored in (and cannot be known at this time), are what other life advantageous factors, other planets may have that Earth lacks. While there may be a few strict requirements for life, there are likely hundreds of life promoting effects, of which we do not know what subset Earth has.
Letter To Iran
Plate tectonics is probably a common characteristic of rocky planets of sufficient size in a second generation solar system. It is maintained by heat mass and energy released from the decay of heavy radioisotopes in the Earth's core.
Mars doesn't have plate tectonics...now. It used to, but its mass to surface ratio is much lower than the Earth's.
The Earth is by far the largest hunk of rocky stuff humans have ever observed. Jupiter could easily have plate tectonics, too. It is just impossible to see under that thick atmosphere.
The outer planets all are either small rocks (Pluto), or gas giants (Jupiter, Saturn, Uranus, Neptune).
Even if something (life, the Solar System, ...) is "designed", this does not make the designer God, at least in the sense of an omnipotent infinite entity. The designed something does not have infinite complexity - even the entire visible Universe is estimated to have probablility of 10^(-10^90) of coming into being from chaos. This is not impossible nor does it require infinite input.
Let's, just for fun, assume that there are such things as aliens with FTL ships but they are not making official contact for some inscrutable reason - too much else to do, we're in a galactic nature reserve, not invented warp yet - that kind of thing ;-)
So what do we have here on earth that *would* tempt your galactic tourist to come looking at us. Especially as they can proberly get a better pan-galactic gargle blaster in the Rigil system?
The answer has to be a total solar eclipse. Even if the Rare Earth hypothesis is correct in that all life-bearing planets have large moons, the chances of the moon being exactly the same apparent size as the sun so as to produce a total solar eclipse as we see them is vanishingly small. Even on earth the window is only a hundred thousand years or so wide because the earth-moon distance changes over time. We are fantastically lucky to be around at a time when there are such things as solar eclipses in the way we see them. Throw in all the atmospheric and biosphere changes seen in an eclipse and we may well be worth a mention in the galactic 'lonely planet' guide.
So the best place to look for aliens would be in a nice remote spot under the path of totality.
By increasing the number of variables in the "Drake equation" the authors make one major error: a lot of the variables they introduce are very close related:
... during this phase you have a sorting of all elements by weight.
/. Live allready existed at that point. And it survived under the ice plate as the ocean was warm enough by vulcanic activities. Not only bacteria but high evolved live like crabs etc.
... it could just be a ice covered ocean world like our world was 400 million years ago. Habouring live, of course.
E.G.
a star of proper mass and:
A constant energy output from the star
are close related to each other IF the star has a similar age like our sun e.g.
I mean: if the star is similar old like the sun and has similar mass like the sun, it will have a similar and constant energy output, like our sun.
For the planet the following variables are not independened from each other or even depend on the variables related to the sun above:
Proper distance from the star.
A proper mass.
Oceans
Plate tectonics.
IF the planet has the proper mass THEN the planet will have plate tectonic. EXCEPTION: the planet is FAR older than our earth.
IF the planet has the proper distance from the star AND the planet has the right mass THEN the planet WILL have oceans.
The bottom line is that many additional factors must be added to Drake's equation. One must keep in mind that as any term in such an equation approaches zero, so too does the final product. For most terms, we have no way of reliably estimating their true value, but it seems like at least some of these values are extremely low
I doubt that. IMHO the approach should be other way around. We shoudl look how many variables indeed are only different expressions of the same basic principle.
There are several astrophysicians which strated to study and make models for solar system creation. They describe how a solar system is comming to existance like this:
You have a big cloud of "dust". Depending on the distance from the galactic core and super novae around that area you will have there a defined mixture of heavy elements and lighter ones.
During star forming the mixture is slowly compressed by gravity
Basicly the same process like in a mixture of liquids and sand and lead in a hot pot: lead sinks to the bottom of the mixture, above sand will settle, then you have the hot water and on the surface you have the oil.
Now imagine you have a dust and gas cloud as big as our solar system. The center is several thousand degrees hot, but FAR from ignition.
There will be several hot spots where bodies are forming. The closer the bodies are to the center, the more heavy elements will participate in the forming.
IIRC some 10 years ago an astrophisics got a nobel price for crafting such star system forming models.
He proofed that our solar system only had one way in "condensating" into planets and that is the way it is visible now.
Well, of course we could have the Venus a bit farer away and Mars a bit closer.
Earth then would probably not exist but Mars would be bigger.
Same for the outer planets, there could be one more or one less. But the distribution of mass from the inner side of the solar system to the outer side would be very similar.
And it only depends on two things: total size of the dust and gas cloud forming the solar system and total amount of heavy elements in the cloud.
Bottom line, if two dust clouds are similar enough (-> size of sun which is ignationed is similar) and in the same distance to the galactic core ( -> distribution of heavy elements is similar) they will condensate to similar solar systems.
If you take ten sun like suns I bet that ALL have planets and that 3 have one or more in the distance of the Venus/Earth/Mars belt.
And those planets will in the size of Mars to Venus. Because there is NO WAY in forming any other planets in any different size or any different distance. (If the system has enough iron and other heavy elements)
There are further variables which are supported by weak arguments: a big moon.
Sure, a big moon stabilizes the rotation axe.
Sure, it might deflect incomming bigger rocks.
But: how important is a stabilized rotatino axis?
During earth history the planet flipped its rotation axe several times by 180 degrees. Yes, what is now north pole was then south pole.
This was recent hsitory! In terms of the age of the earth.
The same for the proper distance, a final quote: There isn't much margin for error here: a change of 5 to 15 percent in Earth's distance from the Sun would lead to the freezing, or boiling, of all water on Earth.
The earth was some hundred million years ago totaly covered by ice. There is a recent story about that in scientific american, it was covered here on
There is absolutely nothing preventing that, to be the normal way in other solar systems. E.G. if Alpha Centauri has a Earth sized planet as far away as Mars
Regards,
angel'o'sphere
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
I disagree with one point. IMO it is much more likely to develop psudeo intelligent machines,
i.e. a "colony" of nanomachines that act like ants, before you develop a thinking machine capable of replication.
These machines while possibly having the drives to survive and reproduce would NOT go to the stars, or even be capable of comprehending it. However, they could easily replace organic life on their home planet. Imagine the troubles life here on earth would have with a self replicating carbon-based nanomachine. Our immune systems would probably be unable to cope with the new invader, and short of nuclear blasts, it would be a real problem to get rid of.
Service guarantees Citizenship! Questions Guarantee GITMO.... Amerika Uber Alles!
This article stinks. While he rightfully points out many more variables that need to be taken into account in more accurately estimating the number of evolved civilizations, surely Drake was aware of many and knew that there were many more factors as well. Drake did something simple based on what he had available to him at the time to make a general point. Seeing as how there is exactly one planet that has (verified) life, it is kind of stupid to try and make concrete arguments about whether or not life, once it starts, is more likely to remain as a bacteria or evolve on up from there. I would in fact argue that due to the lack of any other evidence (and you can really include nothing about the possibility of Martian life since it is very controversial and most people think at this point there was none), based on the fact that the universe is fairly repetitive in its organization, you might say that seeing it evolve here on Earth beyond the simple is the norm rather than the exception once it starts. The other problem I had with this article is the inherent assumption that life must be "Earth-like." If you are going to ream Sagan and Drake for their assumptions, better cover your own ass.
PS Hitler was a practising Catholic but I guess that does not make hom a Christian - after all he wasn't taken up by the rapture.
... is that nobody knows the values of those last few terms. It's not that the concept behind the equation is wrong, it's just that you don't have clue one as to what to plug in there. Nobody has any idea whatsoever the average lifespan of a "technological society". Nobody knows half the other probabilities in the equation.
I actually had some kid at a party state that "it's a mathematical certainty that life exists on other planets". He based that claim on the Drake Equation.
Dudes, having a good sense of what the terms might be is nothing like knowing what values to plug in...
- Steve
Of course! Media coverage of Sept 11th proves beyond doubt that only people on Earth who are Muslim are capable of terrorism! *denote intense sarcasm* Surely Christians, Atheists, Hindus, Jews etc... have never been guilty of any atrocities! *denote intense sarcasm*
Please spare us...
P.S. In case my point was a little too subtle, I'll spell it out: You are being incredibly naive!
"An eye-for-an-eye makes the world blind..." - Ghandi
Civilizations develop or die. They're not static. We've been using radio for less than 100 years, and are already stopping using it in any observable pattern (digital spread-spectrum). Our broadcast/beacon program lasted less than 10 years out of the 3-4 billion that there's been life on Earch. Et may be more patient and change slower, but by how many orders of magnitude?
The inverse-square-law really kills. Don't worry about RF emissions attracting aliens. They don't make it past Jupiter with any S/N. An important benchmark is that Voyager 5 used ~5 Watts power with a directional antenna to the most powerful receiving array on Earth and couldn't get more than 110 baud past Neptune's orbit. Give ET a 10 MW transmitter with 100x greater efficiency, and he's still got to be close, ~10 light-years.
I don't believe we're alone, but I do believe we're separated by unfathomable gulfs of time and distance. Even if we did discover faster-than-light travel, there's still the phasing of civilizations development and the huge number of rejects.
I always wondered how can anybody say something like this: "from these planets that are Earthlike 'x' procent are likely to develope life"
How do they know? It's not like tossing a coin. How can you assign probabilities to something that you have no clue. The right answer can be 0% or 100%, should we use 50% then? Or maybe this sounds too big, let's use 10%. Hmmm! Maybe 13.2453533% What do you think?
A lot of the conjecture I have been reading on this thread seems to support the assumption that life BEGAN on Earth. The problem is that we don't precisely know what conditions necessitated the emergence of life. The logic: life exists on Earth, therefore, life began on Earth, is fundamentally flawed. We are, in effect, presupposing that the conditions required to support the plethora of life on this planet are the same as those required for life to begin. Whilst, this may seem like a baseless and wholly irrelevant observation the Theory of Panspermia is slowly gaining credibility due to recent findings. While I think it is wise to view these finding with guarded skepticism it is worth a look: Panspermia
There are many hidden assumptions here. ET is interested in talking with us ET is interested in Planets ET is carbon based. Is it possible we a just too dumb or dangerous to bother with. Do we need to wait until we genetically engineer ourselves? ET may have had bad experiences with other species and decided to hide. His com system may be point to point so as not to give away their existance. Once ET can create space habitats why would they be interested in planets. Carbon is good for encoding information in long strings and water is a carbon solvent. There are 46 relatively complex chromosomes. Is it possible to produce life with thousands of small chromosomes. Are there liquids that act as solvents for these chemical?
After all until we ACTUALLY FOUND tube worms living at the bottom of the Atlantic Rift living off boiling sulphuric acid we 'naturally' assumed that such a thing was absurd and patently impossible. We falsely assume that ET life would be ANYTHING like us or anything proto-humanoid or 'bear' we see on the old Vid.
What I don't understand is why people are attacking the rare earth book on the grounds that the authors were not Christian, but merely influenced by the work of a Christian.
Leaving aside the issue of whether you can believe in God and still correctly count the chromosomes in a tapeworm, can you find any scientist that wasn't influenced by a God-fearing man?
How about Newton? Aristotle? Or Enrico Fermi, who was a Catholic.
In order to present their work in a secular setting, even Christian scientists will need to have facts.
Sidenote: wait.. so the authors' work is illegitimized by their appreciation of the work by a scientist with a "hidden" religious agenda..? [laugh] maybe they didn't even know he was religious.
-jon
http://jonhuang.com
since the original post was refuting the original illogic by using the rhetorical technique of "reducto ad absurdum", ie making an obviously wrong conclusion using the very form of argument he wishes to refute. Read it again.
One of the major factors relating the Drake equation to SETi is this:
How long does a complex lifeform survive from the time they gain radio technology until they destroy themselves with nuclear bombs or biowarfare technolies?
Since the life of a star is long (billions of years) this short technology time window (in our case less than a hundred years potentially) may (if you're a pessimist about our collective survival instinct) make SETI a long shot. They were out there - but they took themselves off the air...
"Knowing everything doesn't help..."
Io has plate tectonics; it has the most active volcanos in the solar system.
Mars had plate tectonics until quite recently (on geologic time); we theorize that the core is now frozen and tectonics have ceased, but that is, of course, a theory.
Just a small correction.
We wouldn't need a Jupiter to protect us from ASSteroids if there was no ASSteroid belt, right? And earth was supposedly a snowball once, and it remelted from CO2 given off by Volcaones + Greenhouse effect. Basically we don't know crap.
Eat at Joe's.
The problem is this: Yes, we can posit any number of life-forms that don't need air, or water, or DNA, or even a planet. Good for us, I say - that's remarkably open-minded.
But...
To have intelligent life, there needs to be some advantage to intelligence. You can have a Funky Space Alien Bug (FSAB) that is twice as smart as all the others - but what good is that if all it does is, say, float through space collecting hydrogen using an electromagnetic field? Not much- - it doesn't help the bug eat or get laid, so there's no more chance for it's genes to be carried to the next generation than the other, dumber bugs.
To have intelligence, you need life in a place where intelligence matters. There needs to be some possibility that if you're a little smarter, if you can think abstractly, if you can teach your offspring and learn from your parents - heck, if you can learn at all! -, there has to be something to gain from these abilities in terms of staying alive.
Am I making any sense here? What I'm trying to say is that sure, there may be life in environments we may consider so hostile to life, there's no way it could exist. But that life may adapt to that extreme environment by becoming so well adjusted, no further cognitive effort is needed for survival.
I'm the stranger...posting to
dave.
home-automation.org
Ironically, one possibility is addressed in David Brin's "uplift" series (Startide Rising, Uplift War, etc.) Only instead of being the brash wolfling race, we would be the Progenitors that first started uplifting other species.
But as a practical matter we would just overwhelm any existing life on these planets. Even our "primitive" life forms have billions of years of evolution on the competition, and they wouldn't stand a chance.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
People are too used to thinking on a human scale. Look at it this way: if the whole age of the universe were a single year, then the human species would have existed for a fraction of a second. One explanation of the Fermi paradox is that no intelligent species manages to survive longer than that -- a depressing thought.
Donald Knuth is well-known to be a religious man (he has even written on the subject) -- which is why everything written in The Art of Computer Programming is false. I have a marvelous proof of this, but unfortunately Knuth wrote TeX as well, so when I tried to typeset my groundbreaking proof the entire thing was erased and replaced with a copy of the King James Bible. Damn that Knuth!
Cheers,
IT
Power corrupts. PowerPoint corrupts absolutely.
And even here on Earth, where intelligence turned out to matter (humans are kicking all the other animals' butts) we still got by for 4 billion years without intelligence.
Go back in time 50 million years and look at Earth. It has perfect conditions for all the Drake factors, yet none of the lifeforms are building rockets and radios. Earth churned through species by the millions, and still nothing happened for practically forever, until one type of ape happened to turn out weird.
Earth may not be a fluke, but I suspect we are.
As copyright owner of this comment, I authorize everyone to defeat any technological measure which limits access to it.
Completly changed my mind when I was young. I was kind of closed mind, and at 15 I read a book about Einstein theory of relativity (not much math, but well explained). Since then, it really changed the way I look at life. You know, at this age my vision was that we born, we live, we die. Well, it's still what happens, but I am not so sure now about the before or the after or the HOW and WHY? To learn that TIME was NOT a CONSTANT was the hardest thing for me to learn. The point I want to make is that sometimes, scientist are so closed mind that they fail to discover new things because it's not 'normal', it's not in the book! Well, today I know that nothing is really 'true'. It's all a question of understandment and of vision. We don't know a thing, nothing!!! We are looking for other forms of life, but we are still looking for other forms of life like us, not bad in itself, but we just have less chances of finding 'other' life form in the general term. Scientist need to have the same feeling as I had (I think), so they can sit and say themself: "All what I know isn't a fraction of what it is. I'm looking at the whole house by the lock and I understand only part of what I see. I'd rather be openmind cause everything else in the house also influence what I see thru the lock!"
I'd rather be sailing...
"Drake's equation is a statistical calculation, but with no other example for life, we're doing statistics with N=1."
And that's what's always bothered me. It always irked me how Sagan smoothly insisted that life would become intelligent, and the way he calmly made assertions about which he had nothing but his own opinion to back up!
Shutting down free speech with violence isn't fighting fascism. It IS fascism!
I intuitively somehow don't think we can be alone in this universe but what if we are? Does that make us God? Does that make us lords of creation? or would that just make us incredibly lucky?
My own personal feeling is that our moon is what makes life on earth possible. My reasoning:
If you take a look at tides or even at women's menstrual circles, or the lunar calendar don't you get the feeling that the moon is the "heart" of our planet? That it is the thing that makes our planet "breathe"?
If it weren't a single revolution of the Earth, then why didn't God explain it more clearly (in Hebrew, of course) in the first place?
The only reason to spend a second thinking up your "outside the box" solution is because you need an excuse to stay in your own box, i.e., you need some way to keep the seemingly-explicit language in Genesis consistent with your understanding of history.
How about thinking outside your own box: Genesis was written by several Hebrew writers, who were addressing an audience that needed religious instruction, but didn't care too much about how old the universe really was.
1) Makes perfect sense
2) Doesn't require any stretching of the Hebrew text to make it work.
I realize I'm posting this in a forum that practically worships the idea that 'friendly aliens are out there', but I have a karma of 50 so what do I care?
The biggest mystery in terms of alien civilizations is why they aren't here. Why haven't they colonized the Earth? If intelligent life is common then at some point at least one species had the wherewithall to colonize the galaxy. And that species, once moderately into the colonization process, is immune to complete collapse. Any one planet might suffer a collapse in civilization; even thousands might, if they're all affected by the same disaster. But many won't be and since expansion is a given (otherwise they would never have left the home system in the first place) they'll reoccupy any habitable system that goes through this collapse. And if you posit that one species is capable of doing, then others will eventually come along as well.
What this means is that the Earth should have been colonized by *at least* one intelligent species that found it to its liking at some point in the past (distant past, actually). And even if that colony was destroyed it wouldn't matter - Earth would just be *recolonized*, again and again because colonization is what these aliens, all of them, do. Yet it hasn't: we're here and nobody else is, nor is there any evidence at all to suggest that anyone has been here but us. And even if they had been here, in all the long millions of years the recolonization, or new colonization by some other species, just didn't happen. Doesn't make sense.
The 'galactic' disaster theories (a la Niven's Thrint/Tnuctipun war) are so much hogwash - great science fiction, lousy science. Also hogwash is that civilizations advanced enough to begin the process of colonization eventually collapse - every planet, everywhere, all of them in a time frame close enough to prevent recolonization. Uh huh. Again, nice science fiction but there's no rational reason why this should be believed. Another postulation of pseudo-science is the 'Prime Directive' which again has no basis in anything but a TV show popular among geeks. Humans don't practice the prime directive so there's no reason to believe that *every species capable of colonization* is somehow enamored of leaving nice big chunks of real estate alone to allow potential natives to *perhaps* develop into future neighbors. The 'Prime Directive' argument is apologia for why we aren't in contact with a colonization-capable species and isn't something to be seriously considered. The 'we haven't discovered them because the galaxy is so huge' argument is much the same thing, as it doesn't matter what *we've* done; *they* should be here anyway.
All of these are just suppositions, in fact defenses given by the pro-alien crowd for why contact hasn't occurred, and why there is no evidence at all that other intelligent life exists in the galaxy.
Of course, the only sample for life we have (so far) is Earth. Life on earth is incredibly resilient and lives in the most inhospitable of places; it's rational to assume that life exists elsewhere as well, wherever conditions permit. The 'Earth Only' crowd essentially denies the adaptability of life by claiming - without any evidence to support them - that life was a one-time fluke in a galaxy with a hundred billion or more stars. Right. Tell me another, O creationist.
But whether or not life exists elsewhere isn't the point. The question is whether *intelligent* life exists elsewhere. And how do you go about answering that question?
For starters, they aren't here. If intelligent life were common, and throwing out the inane arguments, they should be; they should've been here all along, during our development and before, and they aren't. Okay, so this gives us some idea that while life may be common, intelligent life might be darned rare. Another fact in support of the rarity of intelligent life is Earth itself. Of all the species that have existed over the course of hundreds of millions of years (just taking into account complex organisms, say from the Triassic on up) there has been exactly one intelligent life form. Just one. No others. That is pretty definite evidence that *at least on Earth* (my only sample, and yours too) intelligent life is incredibly rare - unique for this planet. It might very well be a fluke.
So, common sense tells us that life may be common but that intelligent life might be one of those one-in-a-billion shots in the dark. With that we have something to work with. But the question still stands: even if intelligent life is that rare, unless humans are the first to make it this far why has no species colonized the galaxy?
That one is unanswerable, as yet. My hypothesis (completely unsupported) is that once a species reaches a certain technological level, barring accident or malevolence it'll do as we're doing now - ride a roller coaster of technological development that follows an asymptotic curve to a conclusion that we can't even guess at. If this is true, it could be that all species, once they've punched the ticket for ride, reach the technological know-how to travel between stars and colonize planets; but that by the time they get to this level of development they're no longer interested in doing so. It could be that whatever siren-song plays at the event horizon of asymptotic development is far, far more interesting than the pedestrian endeavors of colonizing other planets. That *something* happens to them that draws the entire species into one great collective bent on achieving a goal we can't even guess at - not yet, at least.
And once they achieve that goal, they disappear from the universe as we know it. On to some other playground where our little patch of reality appears downright boring in comparison. Perhaps they go someplace else and mutter 'let there be light'. Who knows? All conjecture, of course.
But if true, it does explain why the universe is so empty. Any species capable of interstellar colonization is no longer interested in colonization. The time frame between discovery of the radio and the Whatever-It-Is that tempts them to go 'someplace else' would be awfully short. Hence no colonization, and no tens of thousands of years worth of radio waves criss-crossing the galaxy.
I have no evidence for any of this, but I believe that Vernor Vinge just might have gotten it right in "Across Realtime". In any event, barring self-destruction or catastrophe we'll hit the 'event horizon' in about 150 years, and then we'll be able to answer the question for ourselves.
Assuming all of this isn't a crock.
Max
My god carries a hammer. Your god died nailed to a tree. Any questions?
It is VERY HARD. And the Biosphere thing is only one, tiny, part of the problem.
Yes, you have to get the biosphere thing right.
Then, you have to expand that model to house a multi-generational breeding population.
Then, you have adapt the model for details like relative darkness, gravity, vacuum of space, and cosmic radiation from which the Sun's magnetoshpere protects us.
Then, you have to replace the Sun as the long term energy source. Both as propulsion and to drive the biosphere.
Then, you have call AAA and get a Trip-tik(tm) to... Ummm... Where? We haven't yet been able to locate an earth like planet. Nearby, or not.
Ok, so you get 8, 80, or 800 people basiclly crash landed on a rock, in the rain, in middle of winter, on some planet uninhabited by life intellegent enough to shoot you, or big enough to eat you, but advanced enough to feed your 2.5 kids. The heating oil guy isn't answering the phone, the electricity's out, and both Home Depot and FoodForYou.com won't ship to your new address. Bummer.
So you might need a shuttle rocket system fueled/maintained from the space side that is capable of escape from an Earth sized body. Now there's a few joules of energy expenditure that isn't likely to come from the Mothership's solar panels.
How long does it take our merry band to build a ground based space shuttle program, let alone the next intersteller spaceship? The first generation of kids will be more interested in exploring what's over the next hill than finding the next planet. A few generations out and you have alot of nomadic tribes fighting for survival, and strikingly few space station engineers.
All this assumes, of course, that the biology of the new planet is compatible with ours. Wouldn't it be an absolute bitch to land and discover Posion Ivy was the root stock for most of the plant life?
All that's left, I think, is for a few million years to pass, without an extinction event, and we can move onto the next planet!
This is all very depressing. With so many possible conditions for the evolution of Intelligent life on other planets, and so many of the factors leading one to beleive that only in identical solar systems would a planet, quite similar to Earth, be able to support life, why even bother searching?
Maybe I should become a Mormon...
(Note: The above statement was one of sarcasm and in no way intended to insult those of the Mormon community)
"You are not a beautiful and unique snowflake."...Tyler Durden
> All that's left, I think, is for a few million years to pass, without an extinction event, and we can move onto the next planet!
An extinction event on either planet during this time would set N back to 1.
The probablities of a successful expansion effort may be lower than the probabilities of all previous and con-current efforts surviving over the same period.
Intellegent life could be plentiful, and even aggressively trying to expand the Empire. But, the astoriods back at the Home World just won't have it.
but wasnt the entire stability of atoms...especialy higher numbered atomic nuclei ones... dependant on the surrounding radiation(cosmic?)...as to how stable they are? and as stated in the article the closer you get to the centre of the galaxy the higher this is...
now i may just be thinking aloud here bout would that mean that in other places, perhaps in a heart of a much bigger galaxy than ours...there could be a say... 1024th element that rivals carbon?
or better yet... Lithium or something... having its attributes changed by the surrounding radiation environment?
i know carbon dosnt really act very well when introduced to the style of radiation found in say, chernobyl... and yet...under this logic, mabye something else *would*
once again, despite my interest in this ; i do know know exactly how it works...
GENERATION 26: The first time you see this, copy it into your sig on any forum and add 1 to the generation.
Evolution requires mechanisms for both variation and selection. One problem is that all the attention is placed on selection and none on the very sophisticated systems that have evolved within complex life to ensure not quite random variation.
The corollary is that selection is popularly presumed to be intrinsically non-random, while there is plenty of evidence from the premature accidental deaths of individuals to the impacts of comets and asteroids that we need to admit a significant fractal random component into our analysis of selection pressures
One clear consequence is that while microevolution provides pressures towards increased efficiency, macroevolution provides counterbalancing pressures towards increased capacity for innovation
The most persuasive argument I see against a creator is all the stuff no intelligent designer would have dreampt of specifying, not even a malicious one.
-- Our systemic servants do not good masters make.
As many have noted, life itself isn't hard, but from there to the Cambrian explosion and the chordates, arthropods and molluscs the Cambrian eventually left us with took 80% of life's history on earth and seemingly the snowball crisis. After the explosion, it didn't take near as long for the range of multicellular life to reach something like today's levels.
The real problem that our anthropocentic perspective keeps hiding is that despite the amazing achievements of millions of animal species in the past couple of hundred million years, only homo sapiens sapiens crossed one particularly significant threshold starting us down a track towards planetary domination, and that less than 100,000 years ago.
To me one really weird thing is that we aspire to communicate with others who have reached a similar pinnacle elsewhere while we haven't managed to get to first base with respect to communication with orcas, elephants or corellas all of whom have useful knowledge and intelligence we aren't smart enough to be able to share.
-- Our systemic servants do not good masters make.
The idea of a chemical origin of life on Earth (and therefore other planets) was proposed simultaneously by Oparin and Haldane in the 1920s. Although they differed about details, their ideas became the basis of the Standard Model of the origins of life.
But in a paper published later Oparin expressed his doubts about the abundance of life based on the unusual location of Earth within the Galaxy. Earth's position is:
1. remote from star-formation areas (with dangerous X-ray bursts)
2. in a sparsely populated region of stars with few chances of collision
3. distant fom nebulae and other dust clouds and thus in a stable chemical environment
Oparin came to the reluctant conclusion that Earth may hold the only life in the Galaxy. He did think, however, that other galaxies had eveloped civilisations. Of course, these would be so remote that any meaningful contact would be impossible,
This is nothing new.
I have been saying this for a long time, especially to those over at SETI, to stop wasting thier money.
The requirements for deep time, that is, a planet that provides a terrestrial environment for many billions of years that is stable is unheard of, in most star systems we observe.
That is, many star systems are either double, have fairly irregular cycles (unstable environments) or lives that prevent long expanses of time too pass with very little variation in solar output.
Remember, it took many billions of years too pass before an organism arose here on earth that could do poetry, go to the moon and otherwise build instruments too look for other sentient beings. Hundreds of millions of organisms came and went in that time.
After all, the dinosaurs, arguably the most successful species EVER, had pea brains, and no intelligence, and they did far better than we have. Intelligence it would seem is not a very good predictor for survival. So it isn't very useful, from an evolutionary model.
In fact, intelligence, may even by a very very bad DISADVANTAGE to a species long term survival. We certainly haven't been around very long, and look at how well the dino's did with far less intelligence than us!
I don't think the physical laws that gave rise to us, are any different here than anyplace else in the Universe. Therefore, I think we can make a safe assumption that intelligent life requires BILLIONS AND BILLIONS AND BILLIONS of years to evolve, MINIMALLY. Even when we look at the fossil record, only ONE species evolved in all that deep time, us.
Intelligent life must be a rare "evolutionary" event, given this evidence.
The money that SETI is spending is wasteful given what we know about stellar topography, which is currently forming a picture of what the average star is, how stable it is, and where its position in the Galaxy is. Even, what kinds of solar systems are "typical", so far bear very little resemblence to our own.
More research is needed, and much more money. About a billion or more would do.
So far most of the evidence, suggests that if we use the Earth as a model, and make the assumption that the same physical laws, and therefore, same possibilities and probabilities exist in the same way elsewhere, civilizations that might exist probably number in the 2-3 range in our galaxy.
We would be one of them.
You can also bet, that because of the amount of time involved, that we are probably many millions of years behind in both our understanding of physical laws, what we think is possible technologically, than this other race.
In short, they are, probably do or have spread throughout the galaxy. Furthermore, they probably can harness the energies of time and matter on a galactic scale, and will not be using anything so stupid as Radio waves, or Laser beams, or other stupid conceptions of how to transmit information.
The whole idea is quaint, and quite ridiculous.
In fact, I would be willing to bet that since they have survived for so long with each other, they are probably watching us right now, asking themselves, "Will this species discover how to live together, and take the first steps out into the void? Or will it destroy itself?" All along, taking very good steps to insure we cannot detect them in anyway, shape or form.
Given the growing body of this evidence, I would suggest to SETI to spend its money in donating it to new initiatives that look for other Earth like planets, which very well could number in the thousands in our galaxy. In fact, there could be a good probability such a planet within 200-300 light years.
We won't know however, if we can't build the space based facilities and technologies to do the searching.
SETI has collected just about 1 Billion or more dollars so far. Ironically, that figure is about how much would be required to build a space based system to answer these sorts of questions, definitivly.
Although intelligent life is probably very very rare, we are quickly finding out, that life evolved very quickly after the Earth formed. It is not unreasonable to assume that many planets have life on them, and I think Rare Earth points that out.
Intelligent Life is Rare, Life is probably not so rare, or is much less rare by an order of magnitude. There really could be millions of worlds out there with pretty strange critters running around!
SETI should assist financially in space based building of such facilities instead of wasting thier time looking for laser beams and radio waves and other such NONSENSE which is not supported by the astronomical evidence.
-hack
Got Geometrodynamics? Awe, too hard to figure out? Too bad.
For example, the sun is 30% warmer than when life started. That must mean there is less greenhouse gases now than in the past. Sure enough, core samples from hundreds of thousands of years ago show CO2 levels that are higher than now. Plant life (mostly microscopic) has been converting the CO2. Of course the CO2 levels can't go much lower, so there will be a state change coming in a few thousand years.
Inorganic science can't explain why we have had an oxygen atmosphere for so long. With out life it is just plain impossible.
Some of the speculations in the Gaia Theory are mind boggling. For example, since lower CO2 levels result in colder temperatures, that would mean there would be more life during ice ages. So the bulk of the life would be in the oceans. As the microscopic sea creatures like diatoms convert CO2 to their shells, these shells start forming sedimentary deposits that are so heavy that they cause the sea floor to press down enough to increase subduction rates and volcanic actions at the plate edges, which releases CO2 gases, which then end the ice age.
Of course this is all still theory, but the book's assertion that everything must be "just right" is it's fundamental flaw, because once single cell life starts using the water and atmosphere, the inorganic sciences will not be able to explain the supposedly "fragile" systems that life creates.
living people are definatly alive, metabolic activity, reproduction locomtion and the same follows all the way down to bacteria.
rocks are definatly dead no metabolic activity, no reproduction and non-locomative
but there are things in the grey zone, are viri alive? no reproduction, they are manufactered by the host, no metabolism again taken care of by the host and non-locomotive but they are considered alive by most people.
let's say viri are non-living just like a computer program with out hardware is non-functional consider ricketsia and chalymedia each class of organisms missing things that we consider part of being alive.
the point is there is no definition of alive just like we know the Earth is a planet and a rock isn't but there is a lot of stuff in the middle, where is the line drawn?
as for me I'll keep on crunching seti@home because it's likly one of us will stumble across some signal that'll lead to an interesting phenomina probaly not associated with an intelligent source.
Apocalypse Cancelled, Sorry, No Ticket Refunds
why does everyone assume that an alien life form will take the same conditions to survive that we do? Maybe the alien life forms need extreme cold or a different type of air. Or maybe the aliens don't need water.
Start with life as we know it - generalized
ATP - chemical bonds - short term energy storage
glucose, etc., - chemical bonds - long term energy storage
DNA - information encoding - long term data storage
RNA - information encoding - short term data storage
polymerase, transcriptase, etc., - encoding and decoding mechanisms
semi permeable membranes - semipermeable barriers - compartmentalization
water & energy (phototrophs, chemo--) - electron source - energy high
water - transport system (building materials, waste, information, components)
oxygen - electron sink - energy low
proteins - functional components
ribosomes - construction mechanism for components per instructions in data
All of above must be able to interact with at least one or two of the others.
complex equilibriums (varied and interacting)
Any life form failing to have all of the general qualities above, we would fail to recognize as living. Not that they don't exist, but we would not know them to be alive even if we met them.
lipids, proteins, complex protein structures - self assembling units
This last does not seem absolutely essential, but it is common to all known life forms ( even some viruses have self assembling protein coats )
The above list is some of those things that are common to all life as we know it and some attempts at generalization. I have my doubts that this list is exhaustive or that it even represents most of the more important principles of life. It does not at all address what principles are involved in building the complexity into life that we associate with intelligence. Indeed our knowledge is so limited that I doubt the ability of mankind's best minds to even come close to preparing such a list.
Given our limited knowledge of chemistry and physics it is difficult to imagine a life form that is not carbon based, and in which water does not play a major role. Water is something of a super solvent with a lot of interesting properties that contribute very significantly to some of the other qualities associated with life as we know it. But who knows what some other compound might be capable of at temperatures and pressures that are rarely observed by us?
The most likely alternative for a life form that makes use of chemical bonds for energy storage with a non-carbon costruction base would be silicon based. The bonds that silicon forms do not admit of as rich a variety in as small a number of atoms as carbon does. This makes such a life form seem unlikely because functional components would of necessity be relatively large in size and life as we know it has a certain elegance difficult to imagine with significantly larger functional components. Some of the objections based on instability of various silicon compounds might possibly find their answers in behaviors at different temperatures, pressures, and in different solvents. While it is simple for us to conceive of silicon based information systems, it is more difficult to picture how they would be integrated with carbon based functional components or how they themselves might be fashioned from components functioning within a chemical system. Material transport systems and compartmentalization are unknowns with a silicon construction base.
Other non-carbon construction bases for chemical bond energy storage are much less plausible than silicon.
Other forms of energy storage do not prompt our imaginations to visualize complex varied and interacting equilibriums, and visions of nuclear or solar powered robots seem the best we can imagine for mechanisms to build functional components. The idea of a self-assembling robot seems almost absurd, whereas ribosomes have apects of self-assembly.
The combination of all the listed qualities is really such an amazing thing that God may, perhaps, pardon us if we are unable to imagine how he might have done it differently.
I think science have a very good explanation about how evolution works.
It is usually given in highschool or college bio classes.
You'd have to redesign a lot of atoms.
For example, water is very special in a number of ways, starting with being very small and highly polar, and working outwards.
In the case of systems like DNA, you have very specific atoms arranged in large, highly ordered groups of groups, to form codons; these codons are bound to their DNA strand (itself amazingly complex); the two DNA strands bound to each other with complementary codons and twisted just so, the whole lot folded, and folded again, each enfoldment a marvel of geometry and held in place by (again) very specific complementary geometry and features (bump-hollow, pluspolar-minuspolar, oily-oily etc). This is just DNA I'm on about so far, we haven't explored the miracles of RNA transcription, the automated untangling that happens as this progresses along the (foleded!) DNA strands, yadda, yadda, or worked up the scale to the incredibly complicated array of interdependent molecular factories, structure and membranes which fill a living cell... I have a couple of huge wall-charts from Roche which show a massive simplification of the 1,000 `most important' reaction paths of the 50,000 _known_ in a cell (and given a typical collection of roughly 2000 organelles in a cell, the 50,000 looks very impoverished, a small fraction of reality). The simplified diagrams look like a collection all of the marshalling yards in the USA, in colour, after an earthquake and a tornado came through.
OK, now if such specific atomic properties are necessary for the operation of this mind-boggling miracle of moelcular engineering, how many other systems of _successfull_ arrangment of the same atoms do you expect to find?
Got time? Spend some of it coding or testing
hehe I don't intend to mean it's something I dwell upon, it had just occured to me, and happened to fit both scenarios. Kind of like "Man in God's image" = god looked like an ape - fits both.
I was the only kid in Lutheran School class that thought coloring Mary white and Joseph black would be interesting.. I spent more time sitting in the corner that year than I ever spent in detention in public school.
"I can't give you a brain, so I'll give you a diploma" - The Great Oz (blatently stolen sig)
Request. When you make an original post, please write an original subject line. I almost didn't read yours -- which would have been a shame. When I get a dozen or so "Re:" replies I tend to assume they're all knee-jerk "Oh yeah?" responses, as most of the responses to "Hello? Fermi Paradox!" were. It's one thing to be disagreed with, but people who just want to tell you that you're wrong are too boring and depressing to deal with.
One day, evil men entered the valley where the scientists and logicians worked. The evil men said that all life sprang from physical effects that we see and can replicate today. Even though no one had ever seen non-life become life without the intervention of life, people wanted to believe the evil men. So, the scientists and logicians looked the other way as the evil men perverted the principles on which the former had stood.
Soon, people began to believe that life is inevitable everywhere in the Universe, even though no one had ever seen any life anywhere else. They made up formulas to estimate many things they had never seen, logically derived from the implications of the lies the evil men had spread earlier. As a result, powerful movements arose that were based on the belief that life must commonly exist throughout the Universe. The End.
There are several reasons that it is difficult to calculate the amount of life beyond Earth. The most important is that no one has ever demonstrated a workable process that will produce independent life forms. Ever. Not even Fox, with his organic soap bubbles. In fact, no one has even the ghost of an idea what it would take to produce life from non-life without the intervention of life. So, any theory that attempts to base an argument favoring abundant life is based on extreme, baseless imagination. We would normally call such people, "fools"; instead, we call them, "evolutionary biologists."
The second reason that it is so difficult to estimate the likely for life beyond Earth is that the few facts we know about life chemistry result in calculations that show that abiogenesis is practically impossible. Even a single incidence of abiogenesis in a trillion years is virtually impossible, based on what is known. But, many people don't want to believe such results, and so, they don't. We normally call such people, "fools." In this case, we have several names for them, including "SETI researchers."
Don't get upset with me; either produce a specific, observable and repeatable example of abiogenesis, or live with the title of "fool."
Taking stuff apart since 1969 (TM)
Any 1984 world, would probably not be interested in expansion. My thinking is any expansion would by necessity mean a loss of power/control over those not on the homeworld. Think about Europe and its expansion to the Americas. Great latitude was given to the "governors" who went West, and you also had piracy etc. followed be eventual independence from Europe. In addition, my argument about the technology is not that they would necessarily be researching doomsday weapons per se, but that any technology powerful enough to go to the stars inherently involves potential doomsday weapons due to the energies etc involved. Technology is a two edged sword. Say you study how to keep a life support system balanced on a ship. You can turn around and most likely use the same tech to make the atmosphere deadly.
Service guarantees Citizenship! Questions Guarantee GITMO.... Amerika Uber Alles!
I bet if these guys were to analyize birth they would come to the conclusion that children are very rare. Yet there are already 6 billion of us. Ah science. You got to love it.
but wasnt the entire stability of atoms...especialy higher numbered atomic nuclei ones... dependant on the surrounding radiation(cosmic?)...as to how stable they are?
No. An increase in cosmic radiation will only destabilize chemistry and make it harder to survive. Organic molecules have difficulty in radiative environments because high-energy particles can disrupt the chemical bonds between the constituent atoms. The properties of actual nuclei do not change with respect to cosmic radiation, unless we go to extreme environments, such as the insides of stars. The possibility of life in such places is very unlikely, and even if it were to exist, it would be difficult to make contact.
A 1024th element would fall apart almost instantly, because (among other things) the electromagnetic repulsion between the protons would be stronger than the binding nuclear force.
Organic molecules have difficulty in radiative environments because high-energy particles can disrupt the chemical bonds between the constituent atoms.
:)
carbon. yes. is there anything that sticks faster than carbon...even if to less things or something like that? lithium perhaps? potassium?...
thank you, though... i think you are probably correct...and i am incorrect.
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Intelligent life on other planets? What about intelligent life on this planet!?
Who's to say that the Star Trek ideal is even feasible!? If people and signals can not travel faster than light at all then it seems we have no chance of exploring the universe. The explorers would just evolve into their own species and maybe if they colonize (..ise?) other planets they would forget their roots and become a distinct civilisation.