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    ET: Anybody Home?
    By Gerhard Adam | February 7th 2010 09:20 PM | 31 comments | Print | E-mail | Track Comments
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    There is a presumption among many people that extraterrestrial life is a foregone conclusion and that it is only awaiting our discovery.  The Drake equation is usually highlighted as many astronomers suggest that with the billions of worlds available, that life is all but inevitable1.

    Equally there is a sense that life couldn't possibly be unique to a single planet, so there is a strong belief that there must be other planets on which life flourishes.  However, we need to consider what the basis for these assumptions actually is.

    In the physical sciences, it is clear that the Earth and solar system, represent a localized version of phenomenon that are readily observable in space.  Therefore when we look at the laws of physics and chemistry we are reasonably assured that whatever applies on Earth is equally applicable elsewhere in the universe.  In addition, the physical sciences are also highly precise in defining the phenomenon being considered, so there is no ambiguity when such scientific laws/principles are being applied.

    In biology the situation isn't quite so clear.  One of the most obvious problems is that there is still no clear definition of what life is.  There are certainly broad definitions and criteria that are presented, but these are fundamentally unsatisfactory and certainly can't be said to apply anywhere except on Earth.  This is clearly seen when examining questions regarding whether viruses and prions are alive.  More specifically consider that if we discovered a prion or virus on Mars, would we consider it to be proof of life? evidence for life? or just a "dead" organic molecule?  The point is that even with such a discovery we still wouldn't have an actual answer to the question of life on other planets2

    Part of the problem is that, unlike the physical sciences, biology has no other environment against which comparisons can be made.  The only evidence for life exists on one planet, and everything that has been learned is only applicable to one planet.  Biology cannot make the claim that its theories or ideas are  universally applicable, since there is no evidence to suggest that life works anywhere else.

    More importantly, by not having a formal definition, we have to consider whether biology is necessarily capable of recognizing life on other planets. Are we assuming that extraterrestrial life will be based on DNA and genetics?  Do we know if alternate configurations or scenarios are possible?

    Despite the billions of other Earth-like worlds that may exist, we also have to consider the problem of how DNA evolved.  Do we assume that DNA evolved identically on other planets?  If so, that would be extremely fortuitous and suggest that life is a fundamentally singular process, however I suspect that biology won't be that lucky.    

    In addition, the question of life on other planets is little more than a curiosity question.  Like wondering if the guys in the freecreditreport.com commercial are a real band (they aren't).  After we know the answer, what difference does it make to anything3?  It isn't likely to advance our knowledge of biology on Earth, since it would be impossible to know what events or selection pressures were in existence on another planet.  In addition, if the basic configuration of life is appreciably different, then there may be no basis for comparison anyway.

    It's probably not worth the risk in bringing extraterrestrial life back to Earth because it could represent unparalleled hazards to our own biology and even if it didn't, we would be artificially modifying the selection pressures on this organism so unless it was confined to the alien environment it would be little more than a "dead" museum piece.  

    Similarly, to extend the search to include intelligent life, seems quite optimistic given the absence of any encouraging data.  I'm not sure why so many people find it difficult to accept the possibility of such uniqueness to life on Earth, or why there is so much resistance to being "alone" in the universe.

    I'm not prepared to say that there can be no life on other planets, nor am I prepared to rule out the possibility of intelligent life.  However, there is also no basis for the presumption of life being pervasive.  Life on this planet wasn't simply the mixing of a few organic molecules, but it was the evolution of microorganisms that "terra-formed" the entire planet making it habitable to the rest of us.  In the absence of such activities, it seems that the search for extraterrestrial life is largely going to be a long, tedious, and not a terribly rewarding process.



    1
    The Drake equation simply assumes that life is simple enough to be reduced to a mere probability of determining how often it occurs. Given our current state of knowledge, any value significantly greater than zero is making some huge assumptions. In addition, it appears that beyond having an Earth-like planet, the moon plays a critical role in ensuring the stability of the Earth at the environmental level thereby avoiding wider variation of conditions for life to evolve and survive.

    2
    Even our knowledge that viruses hijack the cell for reproduction isn't sufficient if we discovered an alien virus, since we have no way of knowing whether such a situation must occur, or whether it is specific only to Earth and cells here.  In other words, viral activity is not a universal law of biology.

    3 It's true that discovery of alien life would likely provide new insights into "origin of life" questions, but it is doubtful that it would do much to extend our knowledge of life as it exists on Earth and until we can explore such a foreign world, it can't answer much from that perspective either.

    Comments

    I think the reason why people are so sure that life exists in other worlds is because life is so resilient on Earth (and space for that matter) and it popped up almost immediately (in geological terms) as the conditions needed were met. Granted, life may form and evolve differently, but it's almost without doubt that whatever life we would find would have needed to evolve due to changing conditions on its home planet or moon, be it environmental or predatory, much like us. Because of that, it is reasonable to assume some level of intelligence given enough time to evolve. Of course it could be a one in a million shot for intelligence to form on a planet with life, but given even conservative estimates of the Drake equation, there would still be a handful, if not dozens of civilizations.

    Also, we know that the building blocks of life are abundant in the universe as formed here on Earth. Amino acids, Hydrogen, Oxygen, etc. have all been found in abundance in various locations in the univerise, it just takes that random chance (or the hand of a creator) to make the combo just right.

    When we examine all of the hurdles life had to overcome on earth to survive to this point (multiple catastrophic impacts, changing environment, the need for a strong magnetic field, liquid water, consistent source of energy, etc.) it does seem impossible that life could still be around, except that it stares back at us in the mirror every morning. If we accept that any one of those variables could have wiped out life on earth it appears impossible that life could exist anywhere else due the narrow probability for us to still be here. However, that probability looks enormous when you consider the truly unimaginable scale of the universe.

    And while it may not change anything here on earth biologically, to know we aren't alone could have a significant psychological impact on us. Whether we are alone has been the profound question since the dawn of man and has been a driving force for exploration ever since. Granted, it won't change our day to day life, but it could steer our goals as a world or civilization in a significant way.

    Do I detect a bit of anti-biology bias here? We are composed of elements that are the most common and lightest in the Universe, which is an unimaginably enormous place. If we found a trace of life on another planet or moon in our solar system, given the abundance of other solar systems, one would have to be perverse not to expect life elsewhere. Metabolism is a good definition of life if you eliminate viruses and prions as living things. But even they cannot exist without the metabolism of other cells for reproduction by invasion. Organic molecules are abundant in the universe. I wouldn't want to venture how many cases of ethyl alcohol, for example, are present in our galaxy. The chemical precursors of life, even macromolecules, have been produced in the lab from natural monomers and simple organics, mixed with inorganic small molecules containing nitrogen phosphorous and oxygen, by input of energy in the form of electricity, kinetic energy of collisions, heat and so forth. Given the above you don't need the Drake equation to understand the probability of life elsewhere. I never thought the Drake equation helped much since we have no values for many of the variables but it is just another way to look at things that are natural to the universe to help see how improbable it would be not to have life elsewhere. Besides, even physics and chemistry experiments only give us conclusions that are probabilities, some stronger than others.

    Simulation experiments based on our understanding of early earth produce the ingredients of life in hours. What we don't know is what happened to those ingredients to give us biochemical cycles that self perpetuate, like the Krebs cycle et alia. We are even at the point of artificially producing microspheres to enclose these cyclic reactions. Despite all this we may never find life because it is too far, may not be intelligent in our sense, may not care to establish contact, or be within our light cone to be able to communicate with electromagnetic radiation, but in my considered judgement it is very unlikely that we are alone.

    Eddie Bollenbach

    Gerhard Adam
    ... one would have to be perverse not to expect life elsewhere.
    Expectation is not certainty and that's my argument.  At present there is no evidence to suggest that life exists elsewhere and most certainly nothing to suggest that it is pervasive.  Whatever the probabilities may be, at present there is nothing except speculation.  What we believe, what we expect, or what probabilities may exist do not create life. 

    While I can understand an element of optimism that probabilities may point to the fact that life exists elsewhere, it is important to recognize that such optimism is just a feeling given how little supporting evidence exists.  In particular, this article was prompted by a previous one that basically announced that life was not only inevitable, but abundant.  Such hubris is simply foolish.

    In addition, far too many people take the concept of life and simply extrapolate it to include intelligent life, once again, presuming that this will give rise to communication.  There is little basis to believe this is anything except a very remote possibility.  My personal view is that we will be fortunate to locate microbial life in the near future and even that is far from assured.
    Mundus vult decipi
    Gerhard Adam
    Of course it could be a one in a million shot for intelligence to form on a planet with life, but given even conservative estimates of the Drake equation, there would still be a handful, if not dozens of civilizations.
    I understand your point, but even one in a million is highly optimistic given the number of species on Earth and the number that have achieved intelligence for communication.  More importantly though, I think too many people take the Drake equation as some sort of predictor model, instead of what it was intended for; simply a way to frame the discussion.  Most of the numbers are completely made up since we have absolutely no way to determine what a reasonable probability should be.
    Because of that, it is reasonable to assume some level of intelligence given enough time to evolve.
    I would agree, but what does that mean?  The intelligence of a dog?  a dolphin?  a chimpanzee?  None of these would do us any good unless we accidently discovered them.
    Also, we know that the building blocks of life are abundant in the universe as formed here on Earth. Amino acids, Hydrogen, Oxygen, etc. have all been found in abundance in various locations in the univerise, it just takes that random chance (or the hand of a creator) to make the combo just right.
    But we don't really know whether other combinations are possible or how they would manifest.  In truth, we don't even know how lucky or common our own evolution is, so it's extremely difficult to extrapolate that to other planets.

    My personal view is that microbial life is certainly more possible  and probably likely.  The higher we move up the evolutionary ladder, the less likely such occurrences will become (at least in the absence of any compelling evidence that suggests it's easy).   However, the main point remains in that without evidence or any predictive models, it is a bit optimistic to be proclaiming that life is all but inevitable (as some recent articles have done).

    Mundus vult decipi
    logicman
    The only behaviour exhibited by all known organisms, I suggest, is evolution of their genomes towards the extension of the organism's range of gene expression between lethal limits. 

    Take for example, an intertidal species with a gene for skin thickness.  Randomness in the cellular environment and in the biome ensures that there are individuals whose ranges along the beach profile vary - ranges between lethal wetness and lethal dryness.

    Small variations in the genome and /or in the biome will ensure a gradual drift of the population into both wetter and drier biome.  Ultimately there may be three distinct populations with three distinct ranges.  By this microprocess the organism acheives the macroprocess of expanding the space within which living organisms may be found.

    The natural result of natural selection is an expansion of life into every habitable part of a planet.  By 'habitable', I mean within the limits which are 100% lethal to all known forms of life due to the known limits of biochemical processes.

    This colonisation process should hold for any planet on which life may have started.  Once life has begun in any form which uses a genetic mechanism having some form of random variation in expression, living organisms will increase their range between lethal limits.

    In order for intelligent life to develop, the requirements, I suggest, are these:
    1 - that organisms shall have evolved to fill the entire habitable planet;
    2 - that one or more organisms shall have evolved a mode of existence such that the entire planet is their biome;
    3 - that they have evolved the means to modify that biome and
    4 - that they have evolved an awareness of their own ability to modify their biome.

    By the above standards, together with the Drake equation there ought to be a lot of intelligent life 'out there'.  By the same token, the almost entire absence of step 4 on planet Earth may be taken by any reasonable and impartial observer as conclusive proof that there is no intelligent life down here.
    Gerhard Adam
    The only behaviour exhibited by all known organisms, I suggest, is evolution of their genomes towards the extension of the organism's range of gene expression between lethal limits.
    The operative word being "known".  Unfortunately we literally have no idea about the requirements, possibilities, or variations that could entail life on any place except Earth.   In all likelihood the conditions that we have on Earth may be exceptional and it may only be due to a random circumstance that gave rise to this particular flavor of biology as any other.  We may find that "natural selection" is a more gentle filter than other environments which could consist of "all or nothing" scenarios. 
    Mundus vult decipi
    logicman
    Gerhard: I think an 'all or nothing' scenario would be confined to either a smaller biome than a fumarole or else a planet with a fairly uniform biosphere.  In either case, there would be no niche to be filled by the evolution of intelligence.

    I was speaking of 'known' in the sense that we know that the mechanism of evolution through genetic change can cause life to expand its range to the prevailing lethal limits.  The same should hold true of any species having an adaptive mechanism.  It could apply to any chemistry of life or even robots.  In fact, since the dawn of the electronic age we have been busy expanding the range within which our robots can operate.  From the bottom of the ocean to the surface of mars, even to the inside of a nuclear power station, our robots have 'adapted' to previously 'lethal' environments.

    I am suggesting that the constant adjustment of fit between genome and environment has cutoff points at the upper and lower lethal limits for all possible genomes.  This idea needs to be understood in terms of a single gene acting in an 'environment' which includes proteins expressed by other genes, or an environment external to a whole organism.

    The constant jiggling between genome and environment would work for any lifeform, for any chemistry, for any planet.  Without some form of 'build-me-list' there can be no 'copying errors', no gene juggling, hence no evolution.

    If ever we discover intelligence elsewhere, either it will have evolved in situ, or it will have been placed there.  I would be more disconcerted by the latter case than the former.
    @Gerhard:

    "I understand your point, but even one in a million is highly optimistic given the number of species on Earth and the number that have achieved intelligence for communication. More importantly though, I think too many people take the Drake equation as some sort of predictor model, instead of what it was intended for; simply a way to frame the discussion. Most of the numbers are completely made up since we have absolutely no way to determine what a reasonable probability should be."

    Well, the "one in a million" was more hyperbole than actual figure, so you'll have to forgive me there. The point I was trying to make is that intelligent life is clearly possible, so any probability greater than zero should still bring back results greater than a handful.

    "I would agree, but what does that mean? The intelligence of a dog? a dolphin? a chimpanzee? None of these would do us any good unless we accidently discovered them."

    Somewhere in the universe, an intelligent being just stated that exact sequence, except added human after chimpanzee :) Basically, you are assuming that we are the pinnacle of intelligence or have reached the evolutionary peak of communication. Sure, given the assumptions I am making we would find countless forms of life below our intelligence, but we our looking for ones equal to or greater than our intelligence. Communication and verification is an entirely different subject. But just finding life out there would be a significant event. If we do, then the models can be adjusted based on the new evidence.

    I think it's clear that "intelligence" is just an evolutionary byproduct much the same as flippers or sight. It gives us an advantage in our environment. We've seen in our own history that given enough time and evolutionary challenges, intelligence evolves. I'm not saying that this a given, in fact I would be willing to cede the point that it is extremely rare. But we now that it is POSSIBLE. Because it is possible, no matter how small the probability, you can use the dreaded Drake equation to come up with an answer greater than 1 (you would have to at least count us, right?).

    There are two extremes to the argument. One says that everytime the conditions of Earth are available, you will have human intelligence every time. The other says that if you take all of the Earths available, only 1 will produce what we consider to be human level (us). Even if you take the more conservative estimates of the Drake equation and work your way back from the first assumption to the latter, there are going to be dozens, if not hundreds, of outcomes that state there are more than one (including us). You seem to be arguing for the latter of the assumptions (let's say 1 of 100). Respectfully, I would say probability is on my side (99 of 100).

    I think anyone with reason would cede the point that we may be the only ones in the entire unimaginable scale of the universe with our level of intelligence (1 of 100). But it is significantly more likely, to the point of *almost* certitude, that we are not alone (99 of 100).

    Gerhard Adam
    Basically, you are assuming that we are the pinnacle of intelligence or have reached the evolutionary peak of communication.
    Not "the" pinnacle, but certainly a necessary pinnacle to move any farther down the path of possible communications.
    I think it's clear that "intelligence" is just an evolutionary byproduct much the same as flippers or sight.
    I don't think that is particularly clear.  When you consider the long history of the hominids, it isn't clear at all that the "intelligence" and knowledge that we're imagining is probable.  In fact, it's entirely plausible that it was a unique accident.  In other words, even if we were to look at "primitive" tribal societies today, they are clearly as intelligent as anyone else, however there is something missing that moved one set of humans down the path of our modern society and another that enabled people to maintain their status quo.  Basically this demonstrates that humans could be every bit as intelligent as we are today and yet never have achieved the technology we currently enjoy.

    If one takes an Australian aborigine and a typical European citizen, it is unlikely that you will find any substantive difference in human intelligence, although you will clearly find a vast difference in their use and dependence on technology.  As a result, the operative question is what created that difference if it isn't intelligence?

    In general, I don't have a problem with anything you're suggesting, but I am suggesting that we tend to frame the argument in terms of what we hope to find and not what is likely.
    Mundus vult decipi
    Amateur Astronomer

    ET Runs For Cover In A Hail Of Bullets.

    I'm not a fan of the Drake equation, and generally view statistical arguments as the result of some assumption that is probably wrong. Testing the assumptions and discovering hidden assumptions is one of my favorite sports. A sample size of one observation does not lead to large confidence levels, considering that the standard error rate is the square root of the sample size.

    Usually I favor the view of many worlds and many universes as the answer to any statistical challenges, but for now I am willing to advance the opinion that when life originally began, it was on one world lighted by one star in one universe. The question then becomes when and where did it happen.

    Origin of life is a rare occurrence, although it started rather early in geologic time on earth, there is still only one genetic code, one genetic alphabet, and one genetic language. It predates oxygen and nitrogen in the air, but requires a certain group of chemicals and minerals, derived from dead stars.

    A lot of work has been done for discovering the age of our world and the age of our universe with the sequence of star formation. Space and time are less well understood, but are key parts of the answer to Gerhard's question. There is a long running debate in which progress has been slow, because many people are opposed to this type of work and would like to shut it down. Every point is argued to an extreme.

    Central to the debate is the Dirac sea of energy. If the energy is very weak, then the human race is quarantined on Earth and will become extinct when our sun runs our of fuel, or possibly sooner. A dozen methods of star travel have been proposed, and all of them depend on a strong energy field in the Dirac sea in one way or another.

    Debate on the Dirac sea is coming to an end with the recent capture of the last remaining strong hold from the opposition. The Dirac sea has been derived from General Relativity without reference to quantum mechanics, and agrees with original predictions from Paul Dirac 80 years ago. That argument is over.

    Science is hard pressed to say where the Dirac sea came from and how it accumulated so much energy. There is one proven science of reflected and focused radiant energy that could account for how the Dirac sea was formed. Radiant focusing is a small power supply, and requires a long time to accumulate a large energy field. In the absence of any other science, or even a theory, or a good guess, the radiant focusing can be put into a calculation to give an estimate of how much time was required.

    The calculation gives an answer of cosmic age greater than universal age by a factor of 10^123. This is the basis of ideas about many worlds and many universes. Cosmic age is sufficient to contain universes more numerous than specs of dust in the deserts, and grains of sand in the oceans.

    Gerhard's question is still valid in this picture. All we have done in this reply so far is to dispose of the Drake equation and all of its assumptions. I don't believe Gerhard was very fond or it any way.

    With statistics pushed far beyond any imaginable horizon, it is time to look for other evidence about whether or not life began here or else where.

    At this point it should be said that with the Dirac victory comes a rather well defined technology leading to design of engines for star travel. With the same technology and the same machines comes time travel, because the vacuum energy is being altered. Gravity induction has been recommended as the best of several Break Through Propulsion choices and can be found on a NASA web page by that name. With gravity induction, extreme acceleration is possible because travelers will not suffer from the force of it. Then the same machines will have the power to move planets from one orbit to another, and stars from one system to another.

    For about 4000 years people have been reporting flying machines in the sky, with a well known report given by Ezekiel, and others from India and South America, ignoring claims from the recent 100 years. With star travel and time travel, we could not say for sure that those machines were not of Earth origin, even if we could find some physical evidence from them to examine. In 4000 years the apparent level of technology has not changed.

    Now the readers should realize that Gerhard's question may never be answered. With the amount of power being discussed, and our worlds propensity for aggression and war, who ever gets the technology first will use it to make sure no one else ever gets it. That's why the Dirac debate lasted so long.

    If Tau Ceti has a civilization with a space fleet that ever visited Earth, they would rush home to turn off the radio transmitters and flood lights. Their astronomers would like that.

    Gerhard gets some of the best papers to write.

     

    kerrjac
    Cool post.
    Some of the search for ET life may be wishful thinking, a projection of our own desires. 

    I enjoyed Carl Sagan as an adolescent; but recently (prompted by GK Chesterton) I've returned to his ideas, and they seem little more than an emotional - perhaps even unscientific - appeal to the scientific mind. It may be given that we are infinitely small creatures in a huge, perhaps even Godless, universe. But how scary would it be if we were truly alone in this huge space? Although it lacks the moral implications, the belief that ET life must exist is to a degree similar to belief in God.

    Underlying Sagan's billions and billions is the assumption that there's actually something out there, which is worth exploring, a mystery worth solving, which can intrigue the common person. GK Chesterton, responding to this appeal 70 years before Sagan popularized it, wrote the following in Orthodoxy
    The size of this scientific universe gave one no novelty, no relief. The cosmos went on for ever, but not in its wildest constellation could there be anything really interesting; anything, for instance, such as forgiveness or free will. The grandeur or infinity of the secret of its cosmos added nothing to it. It was like telling a prisoner in Reading gaol that he would be glad to hear that the gaol now covered half the county. The warder would have nothing to show the man except more and more long corridors of stone lit by ghastly lights and empty of all that is human. So these expanders of the universe had nothing to show us except more and more infinite corridors of space lit by ghastly suns and empty of all that is divine.
    Steve Davis
    Gerhard, you said; there is still no clear definition of what life is. 
    What's wrong with "independent spontaneous cooperation"?
    In my view its value lies in its suitability for everything from a cell to a social group, so would be useful in the case of possible alien life forms. Because it is not overly specific, it steers the researcher away from the pitfalls of looking for "earthy" forms of life.
    Gerhard Adam
    Steve, as I mentioned in the article, the problem occurs in determining what the criteria is that allows us to differentiate between viruses, prions, and whatever else might exist.  Perhaps that division is too arbitrary, perhaps its too stringent, or too liberal.  Whatever the case, the point remains that without a clear concise definition, we're going to have a problem in establishing if life has been discovered. 
    Mundus vult decipi
    Steve Davis
    That's true, but only if we get hung up on an overly specific definition of life.
    If we go to planet X and find anything engaged in cooperative behaviours, then I believe we will have found life. The interesting question then will be to find out how the life form functions, but undoubtedly we will have found life.
    I think we are too "terra-centric" on this.
    Amateur Astronomer

    Exobiology tries to answer these questions, but without any assumption about genetic codes, alphabets, and languages.

    I would expect any life form to have some type of transcribeable genetic information, which would include viruses and pirons at least as parasitic or symbiotic components.

    Lichens, our most hardy life forms are a spontaneous cooperation of two or more unrelated species that could survive alone, but not as well. I believe Lichens are the Earth version of living systems most likely to be found else where. That doesn’t mean the alien colony would have our type of genetic code. It could be a different code, alphabet, and language. Either way it would be one of the greatest finds of all times.

    Science needs to offer these types of possibilities to the public to get support for scientific research. That is where science has failed in the past.

    I was a founding member of Carl Sagan’s planetary society, but dropped my membership at the first opportunity, because the program was rather narrowly focused, and offered very little to the general public in return for the support it requested.

    Star travel is needed for any chance to discover the answer to Gerhard’s question. Public policy is retarding progress in that direction. It isn’t limited by science and engineering. There is a fear that if we establish colonies of life on other worlds in other star systems, and have more than one choice of places to live, then mutually assured destruction would fail as a public policy, and major war would become more likely.

    I covered this topic about 20 years ago in my book Habitat Of Red Dwarf Stars, where I trashed the Drake Equation before it received a name.

    We are hindered in our scientific achievements, by our warlike confrontations.

    Since public policy cannot support star travel, the technology will be advanced privately among small groups, as apparently already happened at least six times in the past 90 years.

    There will be an answer to Gerhard’s question, but it will not appear in public.

    Gerhard Adam
    That doesn’t mean the alien colony would have our type of genetic code. It could be a different code, alphabet, and language. Either way it would be one of the greatest finds of all times.
    If we could tell we found it.  Besides the uncertainties, much of the issue surrounding biology is that we are steeped in its history on earth, so we have all manner of species that we can compare things to and develop conclusions.  Even natural selection is based on the observation of organisms over long time periods to determine how they change.

    If we discovered an alien organism that was markedly different than our form of biology, what could we find out?  We would lack the most fundamental perspective of its evolutionary history since the discovery would essentially be out of context. 

    If it was similar to our biology, then it would be a major coup in establishing universal principles of biology that we could arguably claim have general applicability.  However, if this doesn't occur, then we may not learn much, since such a discovery wouldn't appreciably extend our knowledge of biology on earth, and we would lack sufficient knowledge to understand the newly discovered organism.  It would be like an alien civilization taking a sample from the Earth and obtaining only the Ebola virus.  What would they have learned?
    I would expect any life form to have some type of transcribeable genetic information, which would include viruses and prions at least as parasitic or symbiotic components.
    I would agree, but I'm not at all clear on what that actually means.  After all, how many transcribeable systems might be possible?  Certainly if we found something like a virus, we could lay claim to the fact that some higher form must exist for it to hijack the reproductive machinery. 

    In general, I think the problem is much more intractable than it first appears.  Unlike the physical sciences, biology may well need to invent an entirely new discipline if alien life were discovered, since a completely separate and unique evolutionary history would be needed.
    Mundus vult decipi
    Steve Davis
    Gerhard, you said "If we could tell we found it." That's the point exactly. If we go looking for life we'll most likely miss it, because we'll have in mind the life forms we're familiar with. If we look for cooperation, the chances of succes are much greater.
    Who cares that the definition of life is fuzzy at the margins? If we discover viruses on another planet, that would be an amazing thing. Life is at the far end of a continuum of complexity fueled by energy and the laws of physics. This is an irrelevant semantic concern.

    That Earth is special is at least as much of an assumptive leap as life being widespread; we must assume we are average unless there is evidence otherwise. We've only just begun the work of discovering rocky planets, and everything we discover has moved our solar system and its constituents closer to seeming average.

    How frequent life is we don't know. That it won't exist elsewhere is highly improbable. We can make assumptions based on what we know to be universal physical principles. The conditions favorable to life are specific but not infinitely so. In a big enough universe (and surely ours is) these conditions are destined to be repeated at some frequency. Complex life and intelligent life are surely less frequent than primitive and microbial life, but, again, assuming we're special isn't to appeal to probability.

    Gerhard Adam
    Who cares that the definition of life is fuzzy at the margins? If we discover viruses on another planet, that would be an amazing thing.
    The point is that we can't even be sure that life would resemble the particular organization that it displays on Earth.  Therefore unless we discovered something that possessed a similar structure, it is entirely possible to even miss that it exists.
    That Earth is special is at least as much of an assumptive leap as life being widespread; we must assume we are average unless there is evidence otherwise.
    That's quite a stretch, since we have absolutely no understanding of how life originated, and you're prepared to argue that it's an average situation?  At present the evidence suggests that the Earth is unique.  There is no contrary evidence, so until it is discovered to be otherwise it is not much of an assumptive leap.  I'm not even sure what the concept of "average" means in this context.
    We've only just begun the work of discovering rocky planets, and everything we discover has moved our solar system and its constituents closer to seeming average.
    That's not a very refined comparison.  Given the relatively few number of elements, it isn't surprising that such objects should converge to an average value.  On the other hand, given the millions of organisms and their variations (including extinct forms) has absolutely no basis for comparison anywhere.
    In a big enough universe (and surely ours is) these conditions are destined to be repeated at some frequency.
    That is a probabilistic assumption, but it cannot be considered to be "destined".  I agree that the complete absence of life elsewhere seems implausible, however that doesn't assure that life exists anywhere else, or if it exists that it will ever be discovered.  It most certainly doesn't provide any basis for claiming a certainty, nor that it is abundant (which is precisely what some of the more enthusiastic individuals are already proposing).  My view is that it will be extremely fortuitous for us to discover life anywhere, since our means and opportunities would have to be quite lucky to even find it.  However, regardless of our personal views, there is no scientific evidence to suggest that life is abundant or commonplace. 

    The likelihood of "intelligent" life of a type we envision, I would consider to be highly unlikely. 
    Mundus vult decipi
    Gerhard, are you really discussing default beliefs in the absence of proof of intelligent extraterrestrial life?

    If I choose to believe in a universe teeming with life as my default belief, then as the evidence comes in, I would expect my beliefs to change with it. That the earth is isolated, there is no doubt - and so were many cultures in the Amazon, as an example. These cultures are curious in their own way, using shamanism to actively communicate with and understand their universe. When the modern outside world reconnected, they had quite an adjustment to undergo.

    As a teenager, the prevalent default belief I most came into contact with via discussions and the media, were that the universe was devoid of life. Now it seems more logical to me that the most default beliefs, in the absence of evidence, and guided by physics and such thinking as inherent in the Drake equation, can be really be validly opposed. The position one takes for this issue therefore most likely reflects personal beliefs rather than raw science.

    Also, a modern form of centralism seems to be rearing its head here. To populate one planet in an entire universe (or universes) places humans squarely at the universe's biological center. From this perspective, aren't you taking the position of the pope with regard to Galileo's run-in with church centuries ago?

    Gerhard Adam
    You can have whatever default belief's you like, but that doesn't lend legitimacy to extrapolating a universe filled with intelligent life.  There isn't the slightest hint that such a position is true, despite whether it may be possible.

    Intelligent life is a serious problem because we don't even know what twists and turns produced "us" (and I'm being very careful here), as a species that produced electronic communications and space flight.  The reason for being careful, is that it is entirely possible that a slightly different variation in human existence thousands of years ago, might never have produced such a culture.

    An example I've used elsewhere is that Australian Aborigines are just as intelligent as any citizen of Europe or the U.S., etc.  However, a planet filled with such individuals would not have the electronic communication nor space travel.  It's a cultural difference not an intellectual one.  Therefore even on planet Earth, one can't conclude that such scientific developments are a predictable conclusion of intelligence.

    Without being judgmental about human culture, it is the byproduct of how we've evolved socially as a group and the infrastructure we've formed that produced our "achievements" and nothing that is simply biological.  Therefore to conclude that intelligent life in the universe must resemble humans regarding achievements is flawed.

    I don't have a problem recognizing the probability that life exists elsewhere in the universe, and I also recognize that it probably isn't likely in our solar system.  However, at the end of the day, without more evidence, there really is no reason to take the default position that life is abundant.  That seems unreasonably optimistic.
    Mundus vult decipi
    You said:
    >You can have whatever default belief's you like, but that doesn't lend
    >legitimacy to extrapolating a universe filled with intelligent life.
    >There isn't the slightest hint that such a position is true, despite
    >whether it may be possible.

    Yes, agreed, I can't extrapolate with certainty, but isn't this what you are doing to arrive at your default belief? The bottom line is, if we can't find life out in the universe when we look for it, then scientifically speaking, we can't be absolutely sure why we can't find it. And yes, the sheer size of the 'haystack' we are looking in matters and bears very much on this particular argument.

    Humans have a history of instincts riding over what careful scientific study can clarify, and in this particular case, there just isn't enough conclusive data. Hence, my comparison of your default beliefs and that of the church's with Galileo.

    Default beliefs are rarely discussed or even acknowledged. My main point here is that they can be legitimately separate from data and proof, as long as the line is clearly drawn. Mostly default beliefs are irrational, and so what!

    For example, you said:
    >I don't have a problem recognizing the probability
    >that life exists elsewhere in the universe, and I also
    >recognize that it probably isn't likely in our solar system.
    >However, at the end of the day, without more evidence,
    >there really is >no reason to take the default position that
    >life is abundant. That seems unreasonably optimistic.

    The last sentence gives a hint of your humanity affecting your position. You appear to be saying it is unreasonable to be optimistic. You could also argue that it is optimistic to believe that quasars are powered by black holes, but how is that relevant? I can understand how optimism (or lack of it) can affect your default beliefs, but I fail to understand how you use it to assume that my default belief is unreasonable based on the lack of evidence.

    Do you see more clearly now the distinction I am making?

    (Please excuse my poor html... I've just begun lessons this evening with my nephew, so this should improve...)

    Gerhard Adam
    Yes, agreed, I can't extrapolate with certainty, but isn't this what you are doing to arrive at your default belief?
    Not at all.  I'm not claiming certainty, but only that without evidence, there is no reason to believe that intelligent life is abundant.  After all, the only reason why there's any appeal to the "life is abundant" argument is because the size of the universe is being used to imply that this is a sufficient condition to produce such a result.  However, without having any real understanding about what it takes for life to originate, or how easy/difficult such a step might be, then simply using large numbers doesn't help.

    As I said before, a belief has no bearing and anyone is free to believe whatever they like.  However, beliefs are relevant when it comes to framing the discussion.  In particular, the point is what started as a "possibility" of life, or a discussion regarding the "probabilities" of life evolving on other planets has often been transformed into a virtual certainty that life is prevalent in the universe.  Until further evidence is available, the latter extends beyond mere belief because there is no basis for claiming certainty, regardless of the "size of the haystack".
    You appear to be saying it is unreasonable to be optimistic.
    Actually I'm not using the term in the usual sense of personal optimism, but rather simply as an attitude towards accepting unproven data or suppositions.  I'm pessimistic regarding the wild abandon most people display towards the notion of finding alien life.  It seems that they lack an appreciation of precisely how dangerous such a discovery would truly be. 
    Mundus vult decipi
    Gerhard, I should have read your recent (and excellent) "What Do You Believe?" essay before partaking in this exchange... I find we share many thoughts and ideas about beliefs anyway. A most thought provoking and illuminating article for me, and judging by the comments, for others too. It is clear that ideas and definitions attached to this simple concept have plenty of room for study.

    Back to topic though...

    I'd like to re-present the problem from "universe's" point of view, by exploring three extreme states of the universe, regarding the existence of life within.

    State 1: No life
    - Not True, by definition of our existence

    State 2: Just us
    - Can we agree this is the next best extreme?
    - Demonstrates that life is possible within our universe

    State 3: 'Teeming' with intelligent civilizations.
    - No comment ;-)

    Let us pause briefly to acknowledge that the states between S2 & S3 have been well-discussed in your 'ET:Anybody Home?' essay and comments... I'm not really discussing probabilities here, I'm discussing default beliefs.

    Considering that we know life is possible, and the laws of physics appear to extend to the limits of space and time, then from "universe's" point of view, S2 & S3 are equally possible, because "universe" made the rules.

    Now, idealy the scientific method is neutral, holding no bias either way, so 'ideal' science in this sense reflects "universe's" point of view, and so it should if science's goal is to help us understand "universe".

    Now to bring back your earlier comment regarding my position...
    "
    You can have whatever default belief's you like, but that doesn't lend legitimacy to extrapolating a universe filled with intelligent life. There isn't the slightest hint that such a position is true, despite whether it may be possible.
    "
    ...and let me invert it and see how it looks:
    You can have whatever default belief's you like, but that doesn't lend legitimacy to extrapolating a universe devoid of intelligent life. There isn't the slightest hint that such a position is true, despite whether it may be possible.

    This to me explains why I believe that your position is not based on scientific fact, but it in actual fact none other than a belief. I call it a default belief belief because it awaits further evidence.

    It seems to me you are using your default belief of an universe devoid of intelligent life to say that my default belief of a universe teeming with life is an incorrect belief.

    Yet in your "What Do You Believe?" essay, you said:
    "
    It becomes clear that conflict is inevitable when one set of beliefs is used to suggest that another set is untrue. Note that this doesn't have to change the underlying "facts" or "truth" of a situation, but merely our interpretation of those "facts".
    "
    I feel I have reasonably shown your position to be a belief in the absence of evidence, and in part you seem to acknowledge this. This leaves me confused... Can you clarify to me how you arrived at your belief ,and why my belief is untennable?

    Gerhard Adam
    Can you clarify to me how you arrived at your belief ,and why my belief is untennable?
    I think you've clearly demonstrated the pervasiveness of beliefs when discussing topics that have no evidence to bolster either side.   You're also right that my belief is no more "correct" than the opposing viewpoint regarding the evidence.

    I would not suggest that your belief is untenable any more than I can assert that my belief is the only correct one.  BTW, I do recognize your distinction of a "default belief" when considering such a discussion and agree that this will bias any ideas.

    In my view there is little that can be extrapolated from the evidence since we have the limited case of one planet.  However, this is simply a probabilities argument from a particular "belief" perspective and doesn't hold any more validity than an argument that someone might advance from another direction.

    The only thing we can say definitively, is that we simply don't know what the status of life is beyond our own planet.  After that we can present any number of arguments for or against life, but in the end, we simply don't know.

    Because of that we can approach it (as you've suggested) using those default beliefs and try and make our respective cases.  Obviously if we had an additional piece of evidence, then that would completely reframe the discussion and we could possible find out whether a particular position has become untenable.  If even microscopic life is located on another planet, then my position would become significantly untenable because it would demonstrate that life did exist elsewhere, and after only examining a few planets we found something.  That would suggest either we were extremely lucky in our choices, or that life is quite abundant.  However, your default belief has no such boundary.  No matter how long we search, it is clear that we cannot examine every location for life.  Even if we could, then we have the problem of planets that have ceased to exist or moved beyond our knowledge (by the universe expanding), so there is always an explanation to suggest that life may be "just around the corner".

    I also realize that some of the associated terms add levels of complication to what we believe.  Using the word "intelligent" with life suggests that simply finding life is insufficient, but rather placing the additional burden of intelligence on such a finding.  Similarly, I hope you realize that I don't believe that there is NO life in the universe, but rather that I think it is a less likely event than others may think, and I would argue that most of it will never reach high levels of intelligence.

    So, let me unequivocally say that I am not in a position to argue that anyone's view (including my own) is correct or incorrect. 
    Mundus vult decipi
    Well stated Gerhard, and thanks for giving me the opportunity to clarify my thinking.

    Now I have a confession along the lines of rationalised versus deeper beliefs.

    I've stated that I choose to believe, for reasons of personal convenience, that the universe is full of intelligent life - to what degree, I have left open. But if I were to up the stakes, and say bet my life or the even continuation of the human race (to be dramatic), on wether the universe was full of intelligent life, my belief becomes a little more shakey.

    Quite simply, I couldn't place the bet. I suspect my deeper beliefs are based on my experience of not having physically met an extraterrestrial. This is, no surprises, how I tend to live my day to day life. However, and more signifancantly, I can confirm that by exchanging my default belief to a universe full to some degree of intelligent life, it does affect my thinking in many arenas, even expands it dare I say, even though my belief is actually a rationalised belief.

    On a more local note, I'm really enjoying this blog-site and look forward to more of your thoughts and essays, and also of the other bloggers here.

    Gerhard Adam
    Thank you very much.  I might also add, that your statement illustrates the primary benefit of a belief system; ... it provides us utility in how we view our place in the universe and helps establish our behavior towards it.

    Also, my intent was to dampen some of the optimism that seemed to occur around this view.  I've seen this argument go from life is possible to life is probable to life is certain to life is abundant.  In my view while any of these sentiments could turn out to be correct, it is a far cry from possibility to abundance.
    Mundus vult decipi
    I find it curiously coincidental that the UK Government has recently decided to destroy future ET/UFO files, having released files to the public last year

    http://news.bbc.co.uk/1/hi/7398784.stm

    http://article.wn.com/view/2010/03/02/UK_releases_past_UFO_reports_will_...

    http://www.examiner.com/x-2912-Seattle-Exopolitics-Examiner~y2010m3d1-UK...

    This is supposed to show that there is no conspiracy with, or cover-up of, involvement by Government with any Alien life forms.....

    chuckle, chuckle

    Aitch

    logicman
    Aitch: I note with some cynicism that they are only destroying reports.  What are they doing with the UFOs, selling them on ebay?
    Each new exoplanet discovery raises the odds in Drake's Equation. To stubbornly stick to a human-centric worldview is akin to the Catholic Church's foot-dragging with the ideas of Galileo and Copernicus.

    Gerhard Adam
    Oh please.  Each discovery does no such thing, since the original probabilities were already estimated.  At best, it would predict exactly what was already a guess.  At worst, it would make it even more improbable.

    However to argue that this is akin to the Catholic Church's "foot-dragging" is a pretty striking comparison given that you haven't a shred of evidence to suggest that life exists elsewhere.  Perhaps it would be worth considering that it wasn't like the Catholic Church was denying the existence of the sun, because then you might've had an argument.  This isn't a debate about finding "life" and arguing over what we consider life.  This is the simple fact that NOTHING has been discovered to lend credence to the existence of life.

    While there is certainly a probability (which I have never denied), this is a far cry from certainty.  Wishing it to be true, doesn't make it so.
    Mundus vult decipi