11 replies to this topic

[J.Litobarski]

Hello all

I'm putting together a paper. I'd like to subject my ideas to a bit of "natural selection" to see if they sink or swim. To this end, you'd be doing me a favour if you pointed out any flaws in my argument or any ways I could improve it. But please note: the below is not the actual proposed text for the paper, just the general ideas. I've been sloppy with citations because I've not got access to a library at the moment. When I've got a chance, I will provide proper references for everything.

Here's an abstract:

(1) The synthesis of life in a laboratory would strengthen the hypothesis that life on Earth emerged through chemical abiogenesis.

(2) If chemical abiogenesis occurred on Earth, it is reasonable to assume life exists elsewhere in the universe.

(3) Intelligent life has a higher probability of surviving existential crises (such as the end of a star's life cycle) than unintelligent life.

(4) Therefore the universe selects for intelligent life.

And here is my argument in a bit more detail:

(1) The synthesis of life in a laboratory would strengthen the hypothesis that life on Earth emerged through chemical abiogenesis.

Chemical abiogenesis, the hypothesis that living organisms emerged originally through chemical interactions (i.e. the "primordial soup" argument), has yet to be replicated under laboratory conditions. However, in October 2007 in the UK newspaper The Guardian, biologist Craig Venter announced he had "built a synthetic chromosome out of laboratory chemicals and [was] poised to announce the creation of the first new artificial life form on Earth."

The process used by Venter's team uses an existing life-form (specifically, the bacterium Mycoplasma genitalium) as a host for synthetic DNA. It does not represent complete chemical abiogenesis. However, it does suggest that chemical abiogenesis might one day be possible (and if Venter is to be believed, it may even be achieved in the near future). If chemical abiogenesis were possible, it would have several implications. It would strengthen, for example, the hypothesis that the origin of life on Earth was through chemical abiogenesis. It would also strengthen the idea that life exists elsewhere in the universe, as I shall now discuss below.

(2) If chemical abiogenesis occurred on Earth, it is reasonable to assume life exists elsewhere in the universe.

In the 1960s, astrophysicist Frank Drake suggested an equation to determine the number of advanced civilizations which should be transmitting detectable signals in our galaxy. The Drake equation calculates the average rate at which stars form in the milky way, the fraction of those stars with planets, the average number of those planets that could sustain life, the fraction of those planets that actually develop intelligent life, the fraction of those intelligent life-forms which then go on to develop civilizations advanced enough to transmit detectable signals and, finally, the average length of time such civilizations transmit those signals into space.

In a 2004 article for Wired magazine, Drake wrote that he thought the total number of advanced civilizations transmitting detectable signals in our galaxy could be “a great deal larger” than 10’000. There are estimated to be 100 billion galaxies in the universe and, assuming 10’000 civilizations were transmitting in each galaxy, there would be at least one quadrillion advanced civilizations in the universe. If the number of civilizations in each galaxy is “a great deal larger” than 10’000, then there could potentially be more than a quadrillion advanced civilizations in the universe.

Some scientists dispute Drake's numbers as being wildly optimistic. Geologist Peter Ward and astrobiologist Donald Brownlee argue in their 2000 book, Rare Earth: Why Complex Life is Uncommen in the Universe, that Earth is suitable for life only because of an extremely unlikely combination of geological and astrophysical factors. However, Ward and Brownlee are not arguing that life is unique to Earth, only that life is less common in the universe than Drake supposes. If the conditions for life occured once, then it should be possible (however unlikely) to replicate them. The universe is so vast, that even if intelligent life only emerges once per galaxy, there would still be 100 billion instances of intelligent life.

(3) Intelligent life has a higher probability of surviving existential crises (such as the end of a star's life cycle) than unintelligent life.

The extinction of the human race some time in the current century is a very real possibility, taken seriously by many respected members of the scientific community. Britain’s Astronomer Royal, Martin Rees, has given the human race a fifty per cent chance of surviving the century. Oxford philosopher Nick Bostrom is more forgiving – giving humanity an eighty per cent chance of survival. If an intelligent species isn't wiped out by WMDs, deadly pandemics, climate change, resource depletion, asteroid impact, deadly cosmic rays from nearby supernova, etc, then it will eventually have to deal with the death of its local star.

Our own star, the Sun, is predicted to one day expand into a red giant, swallowing the Earth and sterilising all life. Oxford physicist David Deutsch, in his 1997 book The Fabric of Reality, writes that “if the Sun does become a red giant, it will engulf and destroy the Earth. If any of our descendants, physical or intellectual, are still on the Earth at that time, they might not want that to happen. They might do everything in their power to prevent it”. Deutsch adds that “even if the human race will in the event fail in its efforts to survive, does the pessimistic theory apply to every extraterrestrial intelligence in the universe?”

This is the basis of my argument. Existential crises are an inevitable outcome of the laws of physics. The laws of thermodynamics ensure that, even if a planetary system avoids external threats to life such as asteroids and cosmic rays, the local star will eventually die. Only intelligent life would, potentially, be able to anticipate this event and take steps to avoid extinction. Unintelligent life would have to rely on external intervention.

We can imagine the possibility that some incredibly tough single-celled organism, an extremophile, could leave a planet aboard material ejected into space from the planet’s surface by, for example, asteroid impact. This idea, central to the panspermia hypothesis, was championed by astrophysicist Fred Hoyle. Given enough time, it is possible that extremophiles could spread throughout the universe this way. The advantage of intelligent life, however, is that it can direct its efforts in order to maximise the probability of success. Intelligent life could work to maximize the probability that it would leave a planetary system before a local star expired. Unintelligent life would have to rely on an asteroid impact or some other external intervention in order to achieve the same result. Intelligent life could also attempt to prevent or prolong the death of its local star, which is something unintelligent life could not do.

We could also, perhaps, imagine some unintelligent creature that somehow evolved in such a way that it could survive in the hostile environment of space. This creature's existence, however, is highly unlikely. Furthermore, even if it could survive one existential crisis (such as the death of a star), another, different crisis would likely soon arise for which the creature would have to adapt again or die. Intelligent species have the potential to anticipate and adapt much faster than unintelligent species. Natural evolution occurs on a timescale many times greater than that of human inovation.

Ultimately, the laws of physics dictate that the universe will one day end. Physicist Michio Kaku proposes, in his 2004 book Parallel Worlds: The Science of Alternative Universes and Our Future in the Cosmos, several methods by which intelligent beings might prolong their life beyond the end of the universe. Whether these methods are tenable or not is moot. The point is that only intelligent beings can actively search for methods through which they can escape the ultimate fate of the universe, as opposed to stumbling across them by chance. Intelligent life is best able to cope with existensial crises, including the ultimate existensial crises of the end of the universe.

(4) Therefore the universe selects for intelligent life.

I look forward to your feedback.

Regards
Joe

[marcopolo]

Hello all

I'm putting together a paper. I'd like to subject my ideas to a bit of "natural selection" to see if they sink or swim. To this end, you'd be doing me a favour if you pointed out any flaws in my argument or any ways I could improve it. But please note: the below is not the actual proposed text for the paper, just the general ideas. I've been sloppy with citations because I've not got access to a library at the moment. When I've got a chance, I will provide proper references for everything.

Here's an abstract:

(1) The synthesis of life in a laboratory would strengthen the hypothesis that life on Earth emerged through chemical abiogenesis.

(2) If chemical abiogenesis occurred on Earth, it is reasonable to assume life exists elsewhere in the universe.

(3) Intelligent life has a higher probability of surviving existential crises (such as the end of a star's life cycle) than unintelligent life.

(4) Therefore the universe selects for intelligent life.

And here is my argument in a bit more detail:

(1) The synthesis of life in a laboratory would strengthen the hypothesis that life on Earth emerged through chemical abiogenesis.

Chemical abiogenesis, the hypothesis that living organisms emerged originally through chemical interactions (i.e. the "primordial soup" argument), has yet to be replicated under laboratory conditions. However, in October 2007 in the UK newspaper The Guardian, biologist Craig Venter announced he had "built a synthetic chromosome out of laboratory chemicals and [was] poised to announce the creation of the first new artificial life form on Earth."

The process used by Venter's team uses an existing life-form (specifically, the bacterium Mycoplasma genitalium) as a host for synthetic DNA. It does not represent complete chemical abiogenesis. However, it does suggest that chemical abiogenesis might one day be possible (and if Venter is to be believed, it may even be achieved in the near future). If chemical abiogenesis were possible, it would have several implications. It would strengthen, for example, the hypothesis that the origin of life on Earth was through chemical abiogenesis. It would also strengthen the idea that life exists elsewhere in the universe, as I shall now discuss below.

(2) If chemical abiogenesis occurred on Earth, it is reasonable to assume life exists elsewhere in the universe.

In the 1960s, astrophysicist Frank Drake suggested an equation to determine the number of advanced civilizations which should be transmitting detectable signals in our galaxy. The Drake equation calculates the average rate at which stars form in the milky way, the fraction of those stars with planets, the average number of those planets that could sustain life, the fraction of those planets that actually develop intelligent life, the fraction of those intelligent life-forms which then go on to develop civilizations advanced enough to transmit detectable signals and, finally, the average length of time such civilizations transmit those signals into space.

In a 2004 article for Wired magazine, Drake wrote that he thought the total number of advanced civilizations transmitting detectable signals in our galaxy could be “a great deal larger” than 10’000. There are estimated to be 100 billion galaxies in the universe and, assuming 10’000 civilizations were transmitting in each galaxy, there would be at least one quadrillion advanced civilizations in the universe. If the number of civilizations in each galaxy is “a great deal larger” than 10’000, then there could potentially be more than a quadrillion advanced civilizations in the universe.

Some scientists dispute Drake's numbers as being wildly optimistic. Geologist Peter Ward and astrobiologist Donald Brownlee argue in their 2000 book, Rare Earth: Why Complex Life is Uncommen in the Universe, that Earth is suitable for life only because of an extremely unlikely combination of geological and astrophysical factors. However, Ward and Brownlee are not arguing that life is unique to Earth, only that life is less common in the universe than Drake supposes. If the conditions for life occured once, then it should be possible (however unlikely) to replicate them. The universe is so vast, that even if intelligent life only emerges once per galaxy, there would still be 100 billion instances of intelligent life.

(3) Intelligent life has a higher probability of surviving existential crises (such as the end of a star's life cycle) than unintelligent life.

The extinction of the human race some time in the current century is a very real possibility, taken seriously by many respected members of the scientific community. Britain’s Astronomer Royal, Martin Rees, has given the human race a fifty per cent chance of surviving the century. Oxford philosopher Nick Bostrom is more forgiving – giving humanity an eighty per cent chance of survival. If an intelligent species isn't wiped out by WMDs, deadly pandemics, climate change, resource depletion, asteroid impact, deadly cosmic rays from nearby supernova, etc, then it will eventually have to deal with the death of its local star.

Our own star, the Sun, is predicted to one day expand into a red giant, swallowing the Earth and sterilising all life. Oxford physicist David Deutsch, in his 1997 book The Fabric of Reality, writes that “if the Sun does become a red giant, it will engulf and destroy the Earth. If any of our descendants, physical or intellectual, are still on the Earth at that time, they might not want that to happen. They might do everything in their power to prevent it”. Deutsch adds that “even if the human race will in the event fail in its efforts to survive, does the pessimistic theory apply to every extraterrestrial intelligence in the universe?”

This is the basis of my argument. Existential crises are an inevitable outcome of the laws of physics. The laws of thermodynamics ensure that, even if a planetary system avoids external threats to life such as asteroids and cosmic rays, the local star will eventually die. Only intelligent life would, potentially, be able to anticipate this event and take steps to avoid extinction. Unintelligent life would have to rely on external intervention.

We can imagine the possibility that some incredibly tough single-celled organism, an extremophile, could leave a planet aboard material ejected into space from the planet’s surface by, for example, asteroid impact. This idea, central to the panspermia hypothesis, was championed by astrophysicist Fred Hoyle. Given enough time, it is possible that extremophiles could spread throughout the universe this way. The advantage of intelligent life, however, is that it can direct its efforts in order to maximise the probability of success. Intelligent life could work to maximize the probability that it would leave a planetary system before a local star expired. Unintelligent life would have to rely on an asteroid impact or some other external intervention in order to achieve the same result. Intelligent life could also attempt to prevent or prolong the death of its local star, which is something unintelligent life could not do.

We could also, perhaps, imagine some unintelligent creature that somehow evolved in such a way that it could survive in the hostile environment of space. This creature's existence, however, is highly unlikely. Furthermore, even if it could survive one existential crisis (such as the death of a star), another, different crisis would likely soon arise for which the creature would have to adapt again or die. Intelligent species have the potential to anticipate and adapt much faster than unintelligent species. Natural evolution occurs on a timescale many times greater than that of human inovation.

Ultimately, the laws of physics dictate that the universe will one day end. Physicist Michio Kaku proposes, in his 2004 book Parallel Worlds: The Science of Alternative Universes and Our Future in the Cosmos, several methods by which intelligent beings might prolong their life beyond the end of the universe. Whether these methods are tenable or not is moot. The point is that only intelligent beings can actively search for methods through which they can escape the ultimate fate of the universe, as opposed to stumbling across them by chance. Intelligent life is best able to cope with existensial crises, including the ultimate existensial crises of the end of the universe.

(4) Therefore the universe selects for intelligent life.

I look forward to your feedback.

Regards
Joe

I have been thinking about this myself lately, and I am coming to the opposite conclusion that you do. Here are my reasons-
1. Evidence, SETI has failed so far to find evidence for intelligent life in this galaxy. Not only that, but there is the problem of what is sometimes called the "Fermi Paradox". Basically, he concluded that if intelligent life arose anywhere in the galaxy, and interstellar travel is possible, that any alien race more then a few million to a few tens of millions of years old would have colonized the entire galaxy by now, including earth.

2. It does seem like with all the stars in the galaxy, that intelligent life would be out there somewhere, but I do not believe intelligent life is selected for and is therefore exceedingly rare in the universe. My reasons for this are, first, the prerequisites have to be present for intelligent life to evolve, such as complex terrestrial lifeforms and a mature biosphere. The reason I say terrestrial is that I don't see how an aquatic life form could develop an advanced civilization without first learning to use fire for energy. So earth has probably had a mature biosphere since sometime in the Mesozoic Era (Dinosaurs), or possibly even as far back as the late Paleozoic(just before dinosaurs). With this it is possible for some species to evolve intelligence given the right conditions. However, it took about 300 million years for a mature biosphere to evolve an intelligent species on this planet. One would think that once the preconditions are in place it would have happened fairly quickly, certainly by the end of the Mesozoic, but it didn't. Therefore I believe that intelligence is extremely rare and unlikely to evolve even on a planet with a rich biosphere like ours.

So why then did humans evolve? I believe that it took a series of freak and unlikely events for intelligence to evolve and for us to evolve from apes to what we are now. At any point in this series of events we could have just as easily become extinct. The reason that our ancestors did not become extinct is because there was a strong natural selection for intelligence during those crisis periods. In times when we should have become extinct, instead, the most intelligent members of the species were able to eak out an existence. I also believe that very strong natural selection pressures have to take place for intelligence to evolve. During the time when humans have evolved on this planet has been an unusual time in the earths natural history. Namely, it has been a time of frequent climate and environmental change, and also geological change at the spot on the planet where our ancestors first started to evolve human level intelligence.

During that time, East Africa started to split from the rest of the continent, and this led to a change from forest to savanna over much of the range of our ancestors. They were forced out of the trees and either had to learn to adapt on the open plains, and fight off predators, or they would die. I think this encouraged humans to evolve intelligence and social structure, as well as tool use. But I will try not to get into too many details here. Anyway, our ancestors had to adapt to many changes like this, including the rapid and frequent climate change of the Pleistocene (the so called Ice Ages). For most of our planetarey history earth has had a relatively stable and warm climate, not these rapid glacial advances and retreats every 100,000 years or so, this is very unusual in Earth's history. There are also times when the human race could have become extinct because of our intelligence, such as when the mothers birth canal had to widen in order to give birth to a larger brained baby. How many mothers had to die in childbirth for that to be naturally selected for I wonder?

One other thing I want to mention is that I believe that intelligence is only naturally selected for and not sexually selected for. This is conjecture because I don't know of any studies to back this up, but I think there is strong anecdotal evidence to suggest this. Modern women typically will mate with a tall handsome male and will care less if he is intelligent or not. Intelligence may have an edge now becasue it is easier to become rich with intelligence, but certainly not in the past when brute force allowed the bigger and stronger humans to dominate physically and socially, and the handsome ones to fight off disease better. During times of relative ease it would have been tall handsome males who were sexually selected for, and therefore little or no selection for intelligence. In fact intelligence may have been selected against, because intelligent people tend to come up with absurd ideas that challenge the status quo(like the ludicrous and heretical idea that earth is not the center of the universe). Sometimes they will be persecuted, socially excluded, or even killed for such obscene ideas. It is only in times of great adversity where intelligence would have had an advantage.

I also think the Drake Equation is too optimistic, even with all the stars in the galaxy. Each step in eliminating the possibility of intelligent life is called a "filter", and some people have hypothesized that there must be a "great filter" where the odds of making it through are astronomically low. However, I think it is much more likely there are a series of little filters that would add up to one great filter. Even if the odds were one in 6 of any event happening in a long string of events leading up to intelligent life, it is a logarithmic progression and not a linear one, so with each even modest "filter" the odds increase logarithmically. Basically, if you roll a dice once you have a 1 in 6 chance of getting a six. How about if you rolled that dice ten times? fifty times? a hundred times? The odds of getting sixes every time quickly become astronomical. Well, that is my thought out answer, I could be totally wrong but it is fun to sometimes think about.

[J.Litobarski]

Hi marcopolo!

I'm very happy you posted - thank you for your comments. I'm going to try to change your mind.

Your first point is the Fermi paradox. Ward and Brownlee, in Rare Earth (and also in The Life and Death of Planet Earth), propose that the reason we haven't found life in the universe is because it's much, much rarer than Drake supposed. This also addresses your problem with the Drake equation being too optimistic. I actually agree with you - and I think Ward and Brownlee's modified Drake equation is more realistic. The issue, then, is one of probabilities.

Basically, if you roll a dice once you have a 1 in 6 chance of getting a six. How about if you rolled that dice ten times? fifty times? a hundred times? The odds of getting sixes every time quickly become astronomical.

There may be a lot of filters, but there are not an infinite number of filters. Using your analogy, you would not have to roll a six every time; you would only have to roll a certain number of sixes in a row. Let us say that you need to hit a six one hundred times in a row, to simulate the various steps which need to be passed before intelligent life can form. If you roll the dice one hundred times, the probability of rolling only sixes (unless the dice is loaded) is miniscule. If you roll the dice one thousand times, the chance of a series of one hundred sixes turning up increases, but not by much. Roll the dice 100 billion times, and the chance becomes greater. If you roll the dice one quadrillion times, the possibility of a series of one hundred sixes appearing at some point is by now fairly high. It might even be approaching (but not actually) 100%.

Life might be so rare that the hypothesis that the Universe selects for intelligent life is not justified. This is one of the ways I think it could be falsified, which is (according to Karl Popper) a requirement of a scientific theory. What might be the value at which it is falsified? I don't know. I think the further from 100% the probability gets, the less useful is the hypothesis.

There are also other possible solutions to the Fermi Paradox. It could be that life on Earth is the only life in the Universe. Another solution is that the Universe is still very young, with perhaps another 100 trillion years until it dies. Another is that transport between planets and interplanetary communication is impossible. And then there is the zoo hypothesis or the non-intervention hypothesis.

My point is, however, that we don't have to actually have physical proof of life outside the solar system to make a reasonable assumption that it exists. If chemical abiogenesis occurs when conditions are right in a laboratory, then it is reasonable to calculate the probability of those same conditions being replicated elsewhere.

The reason I say terrestrial is that I don't see how an aquatic life form could develop an advanced civilization without first learning to use fire for energy.

Can I ask where you first read this argument? I remember a similar argument being put forward in the manual to the SimEarth computer game (which was heavily influenced by the work of James Lovelock), and I wonder where they got the idea from.

Anyway – I mostly agree with the argument. It would be highly unlikely, but not necessarily impossible. We can imagine, for example, an aquatic life-form harnessing natural energy – such as the energy from undersea thermal vents. Still, intelligent life is probably more likely on land.

So why then did humans evolve? I believe that it took a series of freak and unlikely events for intelligence to evolve and for us to evolve from apes to what we are now. At any point in this series of events we could have just as easily become extinct.

I absolutely agree. But that refers to evolution within a single biosphere. Not evolution among many biospheres (i.e. planets). Let me put it this way:

Q: In a universe full of biospheres, which biospheres will go extinct?

A: Those biospheres which haven't evolved intelligent life.

Of course, the answer is more complicated than that. Some fraction of those biospheres which have evolved intelligent life will still go extinct. In addition, an intelligent species might prefer to save only itself and not its biosphere. However, we can still say that biospheres which have not evolved intelligence life have a probability of survival of zero, while biospheres which have evolved intelligent life have a probability of survival of greater than zero; perhaps not much more than zero, but the more dice are rolled, the larger that number grows.

One other thing I want to mention is that I believe that intelligence is only naturally selected for and not sexually selected for. This is conjecture because I don't know of any studies to back this up, but I think there is strong anecdotal evidence to suggest this.

As I've said above, selection for intelligent life does not take place within a biosphere, but among biospheres.

Well, that is my thought out answer, I could be totally wrong but it is fun to sometimes think about.

Absolutely! I appreciate your comments.

Edited by J.Litobarski, 15 December 2007 - 08:52 AM.

[marcopolo]

Your first point is the Fermi paradox. Ward and Brownlee, in Rare Earth (and also in The Life and Death of Planet Earth), propose that the reason we haven't found life in the universe is because it's much, much rarer than Drake supposed. This also addresses your problem with the Drake equation being too optimistic. I actually agree with you - and I think Ward and Brownlee's modified Drake equation is more realistic. The issue, then, is one of probabilities.

the problem with the Drake Equation is it is full of unknown variables, and no meaningful estimate can really be made with such minuscule data and small sample size. So far the evidence(SETI results, Fermi Paradox) points to intelligent life, at least in this galaxy, being very rare.

Basically, if you roll a dice once you have a 1 in 6 chance of getting a six. How about if you rolled that dice ten times? fifty times? a hundred times? The odds of getting sixes every time quickly become astronomical.

There may be a lot of filters, but there are not an infinite number of filters. Using your analogy, you would not have to roll a six every time; you would only have to roll a certain number of sixes in a row. Let us say that you need to hit a six one hundred times in a row, to simulate the various steps which need to be passed before intelligent life can form. If you roll the dice one hundred times, the probability of rolling only sixes (unless the dice is loaded) is miniscule. If you roll the dice one thousand times, the chance of a series of one hundred sixes turning up increases, but not by much. Roll the dice 100 billion times, and the chance becomes greater. If you roll the dice one quadrillion times, the possibility of a series of one hundred sixes appearing at some point is by now fairly high. It might even be approaching (but not actually) 100%.

yes, but for each and every planet you would have to roll a six x number of time, say in the range of 30-100 times to get intelligent life, and the chance of one of those string of 30 sixes coming up even once is like, well, my calculator I have in front of me won't even go that high without me getting an error message lol. When you have to use scientific notation you know the odds are astronomical.

Life might be so rare that the hypothesis that the Universe selects for intelligent life is not justified. This is one of the ways I think it could be falsified, which is (according to Karl Popper) a requirement of a scientific theory. What might be the value at which it is falsified? I don't know. I think the further from 100% the probability gets, the less useful is the hypothesis.

I don't know either, we are both speculating.

I used more then my alloted number of quotes, so I have to reply in two messages apparenlty....

Edited by marcopolo, 15 December 2007 - 09:49 AM.

[marcopolo]

There are also other possible solutions to the Fermi Paradox. It could be that life on Earth is the only life in the Universe. Another solution is that the Universe is still very young, with perhaps another 100 trillion years until it dies. Another is that transport between planets and interplanetary communication is impossible. And then there is the zoo hypothesis or the non-intervention hypothesis.

There are other explanations, however I doubt that the zoo hypothesis or interplanetary communication being impossible are very likely explanations. One possibility, and I hope I am wrong, is that civilizations almost all destroy themselves out of stupidity, like some crazy misanthropic individual decides to engineer a nasty virus that will kill most of us and end civilization. Or they run out of fossil fuel before alternative energy sources can be found and go into an eternal technological dark age, or they turn their planet into a mass of grey goo. I hope I am wrong about all of these but sometimes my faith in humanity is not that great these days. It could also be that they find massively multiplayer online games like Everquest more enjoyable then exploring the galaxy. I lost a friend to Everquest once, he got on his computer one day to play that game and was never seen or heard from again, but there is speculation that he fell into his computer or something.

My point is, however, that we don't have to actually have physical proof of life outside the solar system to make a reasonable assumption that it exists. If chemical abiogenesis occurs when conditions are right in a laboratory, then it is reasonable to calculate the probability of those same conditions being replicated elsewhere.

but that probability could be extremely low, which is the basis of my hypothesis. Creating slime in a labratory is one thing, having that slime evolve into a grey or a human there are quite a few steps in between. Even if simple microbial life is fairly common on Earthlike planets, what are the step or steps necessary to evolve eukaryotic cell bacteria? say one in six. What is the chance that the planet they evolve on has active plate tectonics and a reasonable amount of both oceans and land? one in six? How about one celled organisms evolve into something more complex? roll another dice; they form hard shells, and even more importantly, eyes, leading to a biodiversity similar to the Cambrian explosion here on earth? roll another dice... the planet has a moon that gives the ocean tides, allowing intertidal and eventually terrestrial life to evolve and flourish? roll another dice. See how all these little steps could easily add up to an astronomically small chance? I am simplifying it of course but you get the idea. Frankly, I used to think that intelligent life was abundant in the universe, but so far the evidence doesn't point that way so I am just trying to figure out why not.

[/size][/font]

The reason I say terrestrial is that I don't see how an aquatic life form could develop an advanced civilization without first learning to use fire for energy.

Can I ask where you first read this argument? I remember a similar argument being put forward in the manual to the SimEarth computer game (which was heavily influenced by the work of James Lovelock), and I wonder where they got the idea from.

Nowhere, I just thought about it and it made sense to me, that an aquatic life form would have difficulty developing a technological civilization without first mastering the use of fire.

So why then did humans evolve? I believe that it took a series of freak and unlikely events for intelligence to evolve and for us to evolve from apes to what we are now. At any point in this series of events we could have just as easily become extinct.

Q: In a universe full of biospheres, which biospheres will go extinct?

A: Those biospheres which haven't evolved intelligent life. [/size][/font]

Of course, the answer is more complicated than that. Some fraction of those biospheres which have evolved intelligent life will still go extinct. In addition, an intelligent species might prefer to save only itself and not its biosphere. However, we can still say that biospheres which have not evolved intelligence life have a probability of survival of zero, while biospheres which have evolved intelligent life have a probability of survival of greater than zero; perhaps not much more than zero, but the more dice are rolled, the larger that number grows.

One other thing I want to mention is that I believe that intelligence is only naturally selected for and not sexually selected for. This is conjecture because I don't know of any studies to back this up, but I think there is strong anecdotal evidence to suggest this.

As I've said above, selection for intelligent life does not take place within a biosphere, but among biospheres.

Well, that is my thought out answer, I could be totally wrong but it is fun to sometimes think about.

Absolutely! I appreciate your comments.

I think that your main argument is that intelligence has a greater chance of continued survival should it evolve. My argument is that it is rare because of the unlikely probability of evolving in the first place. You may very well be correct that intelligence has a greater probability of survival once it evolves past a certain point, however, your conclusion that this leads to intelligent life being common in the universe may not be true if the evolution of intelligent life is extremely rare in the first place. In a way your argument actually supports my argument based on the apparent non existence of other intelligent life nearby. If intelligent life survives and prospers once it evolves, and it is still rare, that means that intelligent life evolving in the first place is even more rare. I hope I am making sense I am tired and it is way past my bedtime. I wanted to say something else but I forgot what. Maybe I will think of it later.

Edited by marcopolo, 15 December 2007 - 09:51 AM.

[J.Litobarski]

yes, but for each and every planet you would have to roll a six x number of time, say in the range of 30-100 times to get intelligent life, and the chance of one of those string of 30 sixes coming up even once is like, well, my calculator I have in front of me won't even go that high without me getting an error message lol. When you have to use scientific notation you know the odds are astronomical.

Yes, my calculator doesn't go up that far either (it can calculate the probability of rolling about 11 sixes in a row before it breaks). But the amount of dice being rolled might also be astronomical. Even if the chances of 30 sixes coming up is one in a quadrillion, then there's still a chance it could happen in the Universe (obviously it has happened, or I wouldn't be writing you this). What's interesting is that some physicists propose the Universe is much larger than we have so far observed. Some also propose a multiverse, containing a potentially infinite number of Universes. That would be an infinite number of dice being rolled.

In the end, however, the hypothesis doesn't require a multiverse for it to work. Just a sufficiently large universe (which we may or may not be living in). I agree this is speculative - but the hypothesis is (I think) logical.

There are other explanations, however I doubt that the zoo hypothesis or interplanetary communication being impossible are very likely explanations.

I agree. I think the most likely explanation is that intelligent life is very, very rare. Perhaps less than one example per galaxy.

It could also be that they find massively multiplayer online games like Everquest more enjoyable then exploring the galaxy.

Have you read Nick Bostrom's simulation argument?

I lost a friend to Everquest once, he got on his computer one day to play that game and was never seen or heard from again, but there is speculation that he fell into his computer or something.

I sincerely hope he's okay and can be coaxed back to reality.

I think that your main argument is that intelligence has a greater chance of continued survival should it evolve.

Certainly that it has a greater chance of continued survival when compared to unintelligent life.

your conclusion that this leads to intelligent life being common in the universe may not be true

I believe this is a misunderstanding - I'm not saying anything about how common or uncommon intelligent life is in the Universe (except to say that the larger the Universe, the greater the probability that intelligent life will evolve and survive a special existential crises).

Here's a work in progress - the hypothesis in the form of an equation (I realise that the value of G is not affected by the other values at the moment):

IF P = TRUE AND A = TRUE AND (S > X) AND (T > Y) AND (E > Z) THEN THE PROBABILITY OF (N = TRUE) = G

where

P = the laws of physics

A = the hypothesis that life can emerge naturally through chemical abiogenesis and that the probability of life doing so is greater than a certain value (call it V)

S = the total amount of space available within a system

T = the total amount of time available for a system to run

E = the total amount of energy available within a system

N = the hypothesis that a system selects for intelligent life

X, Y and Z = (potentially) empirically verifiable values

Intelligent life could be extremely rare per galaxy, but nonetheless exist many times across the Universe as a whole. These are very large numbers we're dealing with - 100 billion stars per galaxy, 100 billion galaxies in the known Universe, and a timespan of potentially 100 trillion years.

[Luna]

While most arguements are correct, the universe does not select for intelligent life because the universe isn't a being with choice.

Everything is simply following the laws of physics to become as it is, it is obvious that the intelligent will have higher chance of the survive just like the one who knows to avoid getting into fire will survive, while the one who goes in will most likely get burnt to death.

So yeah, intelligent life which will study the universe and by that avoid astroids and anything else is more likely to survive, but it's not the universe's selection, it's just the fact that those life are "intelligent".

[J.Litobarski]

While most arguements are correct, the universe does not select for intelligent life because the universe isn't a being with choice.

When I say "select", I mean the word as it's used in "natural selection" or "artificial selection", not as in "I select", or "she selects".

[spaceistheplace]

While most arguements are correct, the universe does not select for intelligent life because the universe isn't a being with choice.

Human beings are the product of evolution and the universe become aware of itself.

The universe does select for intelligent life if we are the universe and we are evolution in control of itself.

[brokenportal]

(3) Intelligent life has a higher probability of surviving existential crises (such as the end of a star's life cycle) than unintelligent life.

Exactly... Dont you just love how so many people are always like, "we are destroying nature, we are breaking up cycles and making everything deconstruct." Nature constructed us, it seems to me we are nature, it seems to me that nature did its best to produce us this way, we are smart nature and we are the only part of nature that has the capability of surviving. We are the most resilient product of nature and its up to us to do what we can do to be the enduring part of it that survives, the only part that isnt destroyed.

[John Schloendorn]

(1) The synthesis of life in a laboratory would strengthen the hypothesis that life on Earth emerged through chemical abiogenesis.

Venter's work is a very poor reference for this, because he is not even trying to replicate abiogenesis conditions. He simply synthesizes biomolecules in the lab, and surprise surprise they behave just like natural biomolecules. This makes good headlines, but is beside your point. It is long known that the same type of molecules behave in the same ways, no matter where they come from. The question you really want to ask is, can replicating systems spontaneously emerge from non-replicating systems, under early-earth like conditions, and if so is this also true for biomolecules? You might want to look at Jack Szostak's most recent work for some ideas.

[J.Litobarski]

Venter's work is a very poor reference for this, because he is not even trying to replicate abiogenesis conditions. He simply synthesizes biomolecules in the lab, and surprise surprise they behave just like natural biomolecules. This makes good headlines, but is beside your point. It is long known that the same type of molecules behave in the same ways, no matter where they come from. The question you really want to ask is, can replicating systems spontaneously emerge from non-replicating systems, under early-earth like conditions, and if so is this also true for biomolecules? You might want to look at Jack Szostak's most recent work for some ideas.

Thanks for your advice. I'd be interested to know what you think about the rest of the argument.

Nature constructed us, it seems to me we are nature, it seems to me that nature did its best to produce us this way, we are smart nature and we are the only part of nature that has the capability of surviving. We are the most resilient product of nature and its up to us to do what we can do to be the enduring part of it that survives, the only part that isnt destroyed.

I can dig it. We are a bit of the universe with self-preservation.

Human beings are the product of evolution and the universe become aware of itself.

The universe does select for intelligent life if we are the universe and we are evolution in control of itself.

Again - I can dig it. It's not exactly what I'm arguing (there really is no conscious selection process occuring in my argument) but if you define a person as "part of the Universe" then you can say that "the Universe" selects for, say, domesticated wheat strands (where one would usually say that wheat was domesticated by people). This concept might distract a bit from the point I'm trying to get across, though.

Edited by J.Litobarski, 17 December 2007 - 03:24 PM.