Alien Life May Not Be So Alien – If It Exists At All

Article written: 9 May , 2012
Updated: 23 Dec , 2015


Are we too hopeful in our hunt for extraterrestrial life? Regardless of exoplanet counts, super-Earths and Goldilocks zones, the probability of life elsewhere in the Universe is still a moot point — to date, we still only know of one instance of it. But even if life does exist somehow, somewhere besides Earth, would it really be all that alien?

In a recent paper titled “Bit by Bit: the Darwinian Basis for Life” Gerald Joyce, Professor of Molecular Biology and Biochemistry at the Scripps Research Institute in La Jolla, CA discusses the nature of life as we know it in regards to its fundamental chemical building blocks — DNA, RNA — and how its ability to pass on the memory of its construction separates true biology from mere chemistry.

“Evolution is nothing more than chemistry plus history,” Joyce said during a Public Library of Science podcast.

The DNA structures that evolved here on Earth — the only place in the Universe we know for certain that life can thrive — have proven to be highly successful (obviously). So what’s to say that life elsewhere wouldn’t be based on the same basic building blocks? And if it is, is it really a “new” life form?

“Truly new ‘alternative life’ would be life of a different biology,” Joyce said. “It would not have the information in it that is part of the same heritage of our life form.”

To arise in the first place, according to Joyce, new life can take two possible routes. Either it begins as chemical connections that grow increasingly more complex until they begin to hold on to the memory of their specific “bit” structure, eventually “bit-flipping” — aka, mutating — into new structures that are either successful or unsuccessful, or it starts from a more “privileged” beginning as an offshoot of previous life, bringing bits into a totally new, immediately successful orientation.

With those two scenarios, anywhere besides Earth “there are no example of either of those conditions so far.”

That’s not saying that there’s no life elsewhere in the Universe… just that we have yet to identify any evidence of it. And without evidence, any discussion of its probability is still pure conjecture.

“In order to estimate probabilities, we need facts,” said Joyce. “The problem is, there is only one life form. And so it’s not possible to estimate probability of life elsewhere when you have only one example.”

Voyager included a golden record with images and sounds of Earthly life recorded on it... just in case. (NASA)

Even though exoplanets are being found on a nearly daily basis, and it’s only a matter of time before a rocky, Earthlike world with liquid water on its surface is confirmed orbiting another star, that’s no guarantee of the presence of alien life — despite what conclusions the headlines will surely jump to.

There could be a billion habitable planets in our galaxy. But what’s the relationship between habitable and inhabited?” Joyce asks. “We don’t know.”

Still, we will continue to search for life beyond our planet, be it truly alien in nature… or something slightly more familiar. Why?

“I think humans are lonely,” Joyce said. “I think humans are like Geppetto — we want to have a ‘real boy’ out there that we can point to, we want to find a Pinocchio living on some extrasolar planet… and then somehow we won’t be such a lonely life form.”

And who knows… if any aliens out there really are a lot like us, they may naturally be searching for evidence of our existence as well. If only to not be so lonely.

Listen to the full PLoS podcast here.

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74 Responses

  1. zkank says

    Re: “we want to have a ‘real boy’ out there that we can point to, we want to find a Pinocchio living on some extrasolar planet…”

    Wouldn’t finding life on Mars answer that question?
    It sure would satisfy me!

    • Peristroika says

      No, Z, because if we find there WAS life on Mars then we’re still alone and if we find there IS life on Mars, then it’s a simple bacteria or some such that leaves us still feeling pretty much alone as the only multicellular lifeforms. Besides, unless it’s some extraordinary cellular structure, then I would conjecture that it had every right to come from here anyway. Afterall, the moon very possibly came from here and that’s a lot of earth rock in space.

      • zkank says

        That might make YOU still feel alone if a lower life-form was found on Mars, but not me! I guess what level of life would get you excited is subjective.
        (If found, two out of eight planets, and several potential moons ain’t bad odds for the rest of the galaxy.)

        Peristroika wrote: “unless it’s some extraordinary cellular structure, then I would conjecture that it had every right to come from here anyway.”

        I’m not sure I understand that – Considering the sentence following that one, do you mean that when our Moon was formed as per the current accepted hypothesis of another Mars-size object striking Earth, that debris scattered into space and seeded Mars?

        All models I’ve read or viewed show that a) that happened long before life appeared on Earth, and b) both spheres became a molten state after collision, so I don’t see your conjecture as feasible.

      • Peristroika says

        Point well taken. Yes, presumably, that was well before life started but transpermia seems always to be discussed in the “to earth” direction and yet, we know WE’VE got it, so if we can guess at what direction it might go in, well, outward is our only fact-supported direction. Just saying, Mars wouldn’t necessarily prove anything. Unless, as I say, it is a left handed organism or built on something other than RNA or DNA. As for the other moons, they are undoubtedly interesting but clearly, what we’re seeing is that many planets or planetary bodies harbour life-useful systems but that goes without saying with the billions of potentials in our galaxy alone. Here’s hoping and yes, I’ll raise a pint to the martian microbes but it won’t change my view of life in the universe in general.

      • bfmorris says

        “Just saying, Mars wouldn’t necessarily prove anything. ”

        I pretty much agree; I’m too uncomfortable with Mar’s relative proximity to earth to call it a litmus in the case for alien life.

        Though I’m excited about this August, of course non the less.

      • lcrowell says

        If martian DNA were sequenced and found to express polypeptides completely different from what is found with Earth life it would give weight (not proof) these organisms started unquely from Earth life.


  2. Or more likely, life here was seeded by Panspermia even to the extent of incorporating entire gene sequences for higher traits from interstellar/intergalactic microorganism contaminates, such that localized evolution may be more a process of cutting, pasting and adapting pre-existing genetic material rather than evolving it from scratch.

    If so then life is far more complex than anything that could have arisen on a solitary planet as suggested by creationists.

    • Torbjörn Larsson says

      Panspermia, interstellar transpermia, is not likely at all AFAIK. Dormant genetic material is broken down without repair in geologically short order from cosmic radiation if transported outside of terrestrial bodies and from radioactivity if transported inside.

      • Hans Peter Uhrig says

        It may be better to overestimate life than to underestimate it like this example (also in regards to the panspermia theories) shows:
        “D. radiodurans is capable of withstanding an acute dose of 5,000 Gy of ionizing radiation with almost no loss of viability, and an acute dose of 15,000 Gy with 37% viability.”

      • Damian says

        Unless of course Panspermia is not random. Directed Panspermia isnt that far fetched. The human species is reaching out to space atm.

        Put a human on Mars and we will be the instruments of directed panspermia on another world.

        Humans are n ecosystem of microbiology that we may safely transport over the vast distance in a (protected craft) and deliver them safely and alive to another planet.

        = directed panspermia

      • Hans Peter Uhrig says

        We probably already done so (directed panspermia) by sending not really sterilized spacecraft to Mars after and even before the Vikings (eg Russian spacecraft). In regards to Mars I would assume a not isolated common biosphere which we already have some hints off (Viking life-detection and Martian meteorites) . Cross-contamination may have happened before us already and chances are that Martian life (extinct and extant) is related to Earth life in some way.

      • Hans Peter Uhrig says

        We probably already done so (directed panspermia) by sending not really sterilized spacecraft to Mars after and even before the Vikings (eg Russian spacecraft). In regards to Mars I would assume a not isolated common biosphere which we already have some hints off (Viking life-detection and Martian meteorites) . Cross-contamination may have happened before us already and chances are that Martian life (extinct and extant) is related to Earth life in some way.

      • Torbjörn Larsson says

        Not very likely.

        – If Mars is (was) habitable, life evolved there by itself. Mars aggregated way before Earth, ~ 4 million years as opposed to ~ 40 – 60 million years. (If the new Sm clock rates are accepted.)

        Then we have the subsequent sterilizing Earth-Moon impactor, likely somewhere 180 million years ago. (Another recent re-dating.)

        – It is highly unlikely such life could have transported to Earth, and even if there would be a small likelihood – the time window before life evolved here wasn’t large. Some abiogenesis theories claim 10’s of thousands of years as upper limit. Mars-Earth transported impactors aren’t that frequent.

      • Hans Peter Uhrig says

        “If Mars is (was) habitable, life evolved there by itself.”

        That would be the most important finding of science ever – strangely nobody seems to realize this and no real attempts have been made to follow up the Viking results to date. A comparable cheap and miniature chiral version of the proven Viking LR experiment could yield some astonishing data in this regards. Fortunatly such has been proposed as part of the BOLD mission concept which could fly in 2018 – just only 42 years after Viking(!) 🙂

      • Torbjörn Larsson says

        First, D. radiodurans has a one off repair trait, phylogenetic work has managed to show that it is a side effect of having evolved a special stress response to survive severe drought.

        Don’t expect it to be common, and don’t expect it to evolve among more ancestral cells.

        Second, as I said earlier this repair mechanism doesn’t work in space. Eventually its DNA will be too fragmented and its cellular machinery too damaged to make a successful repair.

  3. there is no alien life… and this is the stand of universe today eversince… it must not change…

  4. Peter O'Connor says

    i find this article…disturbing…mainly because the best thing the author can come up with is “I think humans are lonely”.

  5. Torbjörn Larsson says

    Gerald Joyce wrote an obituary of Leslie Orgel, who famously couldn’t see how chemical evolution achieves catalytic closure as in cells.

    I’ll have to read the paper, but the hypothesis that there is a qualitative phase change between distributed chemical evolution and its progress to localized reproduction in cells is not very predictive and has not been tested as of yet. The more parsimonious hypothesis is that there was a gradual localization and increase of inheritance.

    And as I always complain, and it could be the case here, information is relative a system and a chosen measure, there is no inherent quality associated with it.

    the probability of life elsewhere in the Universe is still a moot point — to date, we still only know of one instance of it.

    As we recently have discussed around elsewhere on UT, this can be noted to be a basic mistake concerning stochasticity.

    Modern probability theory involves stochastic processes, and there estimates suffice to pin down parameters. That single observations suffice is true here as well as heuristics for exclusion values, if the observation is too uncommon for the process.

    We are lucky. The parsimonious model is a Poisson process of chemical evolution successfully attempting to progress to biological evolution and with the observed values for Earth it roughly passes a 3 sigma model test:

    To simplify we use a normed distribution where observation time t = 1. Since this is a one-sided interval from t = 0, we want to have a set of distributions with at least 0.99 of the probability mass within the interval.

    The probability mass is expressed by the cdf (cumulative distribution function). Inserting into the Poisson cdf, we get F(t,?) = 1 – exp(-t*?) ? 0.99 ? t*? > 4.6.

    Now t = 1 corresponds to ? ~ 5. That means the normed waiting time T ~ 0.2. With actual time t* ~ 5 Gy we get actual waiting time T* ~ 1 Gy.

    With current understanding we have putative observations of life from ~ 3.8 – 3.5 Gy ago. Earth aggregated ~ 4.5 Gy ago, which means the interval gets close to the required ? 1 Gy.

    We don’t have to in the basic model but can further assume that chemical evolution is roughly the same everywhere. The extended model is well tested by observation in our local system as well as cosmologically, the same chemicals and general pathways are observed.

    On the other hand the old “low likelihood, many planets and long time” model of Monod is not amenable for a stochastic process model what I can see. It looks like a description of a dynamical system with a vast process space that is frequently revisited and have a small volume for “success”.

    This deterministic looking as opposed to stochastic looking phase space should give supporters reason to pause, how do you derive and discuss probabilities for such a model? More likely it is an untestable and on the face of it non sequitur “just so” story.

    • bfmorris says

      “”This deterministic looking as opposed to stochastic looking phase space should give supporters reason to pause!””

      How would this square with our stochastic universe?

      Life appears similar to the invisible dark matter I read about. We can’t see it, we can only observe its effects. It appears life is invisible; some kind of invisible management system or program, for lack of better word. We can only observe its effects. In this case, what appears to be invisible employment of organised chemistry that among other things, temporarily outwits the second law of thermodynamics.

      • Torbjörn Larsson says

        There are plenty of deterministic processes out there. Planetary orbits, star evolution main series, et cetera are short period deterministic. Or you can narrow it down to impact shocks (real short period) and so on.

        I can’t follow your argument in the middle part. The biosphere is plenty observable.

        The thermodynamics is all wrong, there is no TD problem. You could as well say that refrigerators outwit TD.

      • bfmorris says

        re the middle part:

        What I mean is, and I’m not arguing with you, it appears thus far that the most we can observe is life’s effects; ie on the matter it employs. The atoms in you or me are the same atoms found elsewhere. There is nothing special about them, and we would not be able to differentiate the atoms in us from those in a rock or a rain drop. However, no matter how many times we throw atoms in the proverbial air, we can’t recreate what we observe. The effects on those atoms, by life, are all we have at present for the observation of life. Thus my dark matter analogy, partly in levity, because we can’t see life we only see atoms and molecules behaving strangely together. Perhaps life is a form of unknown emergent energy; which reminds me that we don’t know exactly what energy is, either; we can only observe its effects.

        The entropy stage of life appears to be, death, which appears to be observable. The atoms and molecules in the dead organism immediately start acting like themselves again. The organism decays, atoms and molecules blow away, evaporate, get eaten and look special again because they are employed in another organism, or whatever.

      • wjwbudro says

        Very intuitive. I’d like more discussion on this thought.

      • TheMatrixDNA says

        Very intuitive, Mr. “bfmorris”. As wjwbudro, I’d like more discussion on this thought.
        Why atoms behaves different in living organisms? I think the answer is in the hierarchy of natural systems. Must be an invisible natural system inserted inside these atoms and acting from above over them, changing its normal behavior when free. The most clear example is the system of religion acting from and over a biological system called human being: the normal fighting for survival can became a suicide bomber. Or sun’s flares over Earth magnetic field. Then we have Matrix/DNA Theory models suggesting how a galactic system is half-mechanical/half-biological and how its building blocks are like nucleotides, and, how the laws and behaviors of this galactic systems penetrates earths’ atoms driving them to re-organize as a copy of that astronomic system. What you say “some kind of invisible management system or program” maybe is just the matrix formula showed in my website.

        But that is not the whole history. The formula is suggesting that any atom has the blueprint and non-expressed functions for all seven properties of life. The radiation from its nucleus produces seven different frequencies of vibrations, like the light waves. This is the magnetic field of any atom. When an electron is positioned over a specific electrosphere, the field expresses a function, like, let’s say, from your body we could see only one organ and its systemic function. if this is the right configuration of atoms systems, then became ease the bits from galactic entropy driving those atoms to re-organize in a biological fashion.

        About entropy, I think that the official theory is non-complete because they have no known complete natural system for observing. We can see the effects of entropy over natural systems, living or not living, in my model of a complete natural system. Cheers…

    • RemyVTR15 says

      You knowwww, it’s people like Mr. Larson that give me goose pimples. (And I mean that in the best and most respectful manner). I can only truly sit and wonder about the actual mathematical “brass tacks” that dissolve all the factors down to single basic equation. I hope you sit back and truly consider yourself lucky and fortunate to orchestrate your abilities into a concise and readable form to laymen like myself.
      All that jargon and mathematical wizardry to say what seems readily obvious… Some magical power made all the nuances and accidents come together…here.

      Such coincidences in such a vast universe would be deemed what mathematically?

      In a more philosophical way, in the debate whether or not God is real, the fact that we can mathematically conclude that we are ‘lucky’ should give rise to the option that Earth may have been purposefully seeded. Until we ‘know all’ that option is as valid as any.

      And if we are alone…amongst billions of star and trillions of planets… then what a waste of space. And we all know that runs counter to what we find here on this world. God, nature, accidental perfectness…whatever u call it, there is nothing on this orb without purpose and use.
      That simplistic fact should give all of us comfort as we continue to look outwards… And of course if there isn’t other life forms, that means all is available to colonize without war and conflict (with others).

      So, win win either way.

  6. arthur_gould says

    Microbial life most likely is under the soil on Mars. It is probably in Europa’s ocean. The Universes’ purpose is to harbor life. Come on people, My glass is half full… of a great Stout!!!!! Booooyaaaahhh!!!!!

    (Created by microbial life- Yeast)

    • dwdeclare says

      universe’s purpose? the universe needs neither life nor a purpose to exist. it may perhaps be inevitable that given unlimited time and unlimited space, with all manner of physical processes stirring and mixing chemistry about, sentient life will arise sometime, somewhere in the vast expanse, but that in no way implies that the universe is somehow fulfilling it’s “purpose”. teleological final causes are the stuff of fairy tales, fantasy and religion…not science.

      the universe doesn’t have a purpose but we do. and it’s to drink beer on saturday afternoons eating nachos while watching 5-pin bowling on a big screen tv. it don’t git no better than that!

  7. The Bobs says

    “The amino acids that form DNA here on Earth”

    DNA does not contain any amino acids.

    • arthur_gould says

      adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T)

      • Torbjörn Larsson says

        Those are the nucleobases that goes into the DNA nucleotides.

        My take was that “the amino acids that form DNA here on Earth” is a description of the cellular machinery, of mostly proteins, that produce DNA.

        Those cells have been successful indeed, having survived for ~ 4 billion years and as it looks relegated their RNA cell ancestors to parasitic virus niches*.

        Since the Virus domain is polyphyletic, has last common ancestor outside the group on account of some groups having closer affinities to Eukaryotes, Archaea, and Bacteria respectively, some people describe it as a possible niche of parasites.

        Some DNA viruses seem to be extremely parasitically simplified descendants of cellular life forms, some may be de novo RNA parasites, some may be early RNA world descendants.

    • You’re right. Reworded for better accuracy.

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  11. Considering the scope of our knowledge universally speaking saying that we haven’t found any evidence and hence must assume at least for now that we are alone is a little ridiculous. The media often makes it seem like we have this amazing view of the cosmos but in reality we look at tiny sections and any kind of overall view we have is extremely general. The area of the universe that is actually observable as far as searching for evidence of life goes is so tiny it’s like dropping your keys on the beach checking under your foot and saying that that because they are not under your foot we must for the moment assume they are not on the beach.

  12. Dunc Kaas says

    This was in last seasons Through the Wormhole already 😛

  13. Tim Tomakin says

    The problem is that they are searching for life as we know it, using the chemistry of the human race. We only know what we’ve learned from this planet, the chemical makeup of other galaxies or life forms can easily be very different from anything we know about. This close mindedness disappoints me coming from scientists who are aware of how vast space is.

    • Dunc Kaas says

      Actually, they’re looking for communication aswell, as from studies has showed that all communications have the same basic principles (between the higher life forms) and that dolfins and the like follow the same ‘similarities’ in their communcation as human languages. So that even if we cannot understand or unscramble a language, in theory we should be able to spot communication from background noise. As alien or not, they are bound to the laws of physics as are we. (or maybe not, but no use looking for something if we dont have a clue what to look for :P)

    • Peristroika says

      Yeah, we’ve looked at galaxies billions of years distant and seen the signature of chemistry we know and understand. Since chemistry follows physics and physics seems to be universal, scientists are working with a solid set of conjectures as opposed to you who would like to think we know nothing and so can guess at anything.

    • bfmorris says

      With the debunking of the arsenic story, how do we know your statement “the chemical makeup of other life forms can easily be very different from anything we know about” to be true? What other elements have the same properties as our life forms?

  14. lcrowell says

    If something is not absolutely forbidden by physical principles it is then mandatory. The lack of some physical impossibility for a state means this state exists in the set of possible states in the universe. In that state space there is some measure, whether that be an orbit space, orbifold or a probability distribution which can estimate the frequency with which that state occurs.

    Life in the universe in a natural philosophical sense is not likely to be forbidden. One might maintain that life on Earth is some fluke of happenstance which permitted something with zero probability to occur. Some would argue that fluke is a supernatural intervention. We might say that if the universe is infinite that the occurrence of life on Earth is a case of an infinitesimal probability, but that gets into some singular issues I will avoid here. So within the bubble nucleation zone of this observable universe, existing out to the particle horizon of some 200 billion light years out, the number of stars is around 10^{18} — a billion billion. This means that if abiogenesis is not forbidden, or the probability for it not infinestimal, but is rather something that has a natural process then it does certainly seem reasonable to say that amongst this vast number of planets there is life elsewhere. Indeed there should be intelligent life elsewhere.

    What Torbjörn Larsson argues with Poisson statistics is that one can estimate a Bayesian prior from a cumulative distribution function. The exp(-?t) ~ .69. So we can argue from this basis that a prior estimate exists and it is nonzero.

    This stochastic argument can be advanced in a Bayesian formula P(A)P(B|A) = P(B)P(A|B). The conditional probability used would then have to come from astrophysical data for the occurrence of earth-like planets. We have some data that is suggestive, but as yet I am not sure our confidence is high enough to perform a serious estimate on the distribution of biologically active planets in the universe.


    • RemyVTR15 says

      What I would like to know, and it seems obvious to me, if there were ‘accidental’ and luckiness in our planets ability to have life… what about the numerous extinction events and the fact that while scientists agree that comets and the like carried life giving and other elements necessary for life.. all the while most incoming comets/asteroids have been gobbled up by the outer gas planets, especially Jupiter? Perhaps your equation takes this into consideration, but with ‘super Earths’ being found, wouldn’t it be plausible that they too would be impacted by these life-giving rocks and thus seeded at a higher rate than we have been? I see from further reading of your post, you do mention that we don’t have enough information. But with the distances separating us and other planets, can we really forsee the day when we will have that definitive answer? Other than Mr. One-eyed Greenman visitations?

      It would seem that our blue planet is very durable and has resisted several ‘kill shots’ in the past and life has continued. And oddly, each time it seemingly has bounced back with more capable beings. This argues some point about randomness, but I defer to brighter individuals for that.

      • lcrowell says

        A solar system is actually a deterministic system. However, there are sensitive dependencies on initial data, aka chaotic dynamics. Knowledge of that determinism requires an infinite floating point precision. The problem of course is that out to 10^{30} decimal points a computer that occupies a 10^6m^3 volume that processes this volume of data will implode into a black hole. So the determinism of nonlinear classical systems is really an idealization.


      • ToddReece says

        yeahhh, ofcourse … I was asleep during that class.

      • lcrowell says

        Information has a connection to energy and entropy by the Shannon-Khinchin theorem. If you had a computer that could accumulate ever greater amounts of information the energy equivalent would be so large at some point that it would have sufficient gravity to become a black hole. Strange, it is true, but this universe is stranger than we often at first think it is.

        This also means that observables in the universe can never be measured with complete certainty, even if you expand the uncertainty in the conjugate variable arbitrarily large. The number of degrees of freedom we can describe in the universe in some complete manner is far smaller than we currently think they are.


      • bfmorris says

        Does the universe by definition have to be finite, because it has a beginning? Thus is the information contained in it, is finite, though ever growing thus eventually the blackhole?

      • lcrowell says

        Information has a connection to energy and entropy by the Shannon-Khinchin theorem. If you had a computer that could accumulate ever greater amounts of information the energy equivalent would be so large at some point that it would have sufficient gravity to become a black hole. Strange, it is true, but this universe is stranger than we often at first think it is.

        This also means that observables in the universe can never be measured with complete certainty, even if you expand the uncertainty in the conjugate variable arbitrarily large. The number of degrees of freedom we can describe in the universe in some complete manner is far smaller than we currently think they are.


    • bfmorris says

      I’m unclear how infinity would work. Can bona fide infinity have a beginning, or does bona fide infinity require no beginning and no end? Also what about, say, something that has a beginning point and an end point, but never before occurred and doesn’t ever reoccur for infinity or forever, for lack of a better word? Does infinity even really exist outside of our minds?

      I’m also unclear (re the recent thread about math being more than just man made) how mathematics can be universal in a stochastic universe. We’re using math to predict the existence of ET, but does the universe really owe us mathematical odds? If the universe is mathematical, it seems the answer is yes, but if not….?

      • lcrowell says

        Stochasticity is a branch of mathematics. This also gets into questions about Kolmogoroff entropy and the indefinability of randomness. If time permits later today or tomorrow I might expand on this point.

        Does the universe owe us mathematical odds? That depends, but from a Bayesian perspective the update of a Bayesian prior can be seen as our acquisition of increased data. The frequentist perspective is one where there exists a defininate ensemble with a distribution of probabilities.


      • bfmorris says

        “”Stochasticity is a branch of mathematics. This also gets into questions about Kolmogoroff entropy and the indefinability of randomness. If time permits later today or tomorrow I might expand on this point.””

        Does infinity’s definition represent the same indefinability?

      • lcrowell says

        Infinity turns out to be strange with a hierarchy of infinities. The lowest infinity is uncountable infinity ?_0 and the next level ?_1 = 2^{?_0} is uncountable infinity. These are a part of George Cantor’s transfinite numbers. This formula however is not proven and is the continuum hypothesis (CH). Bernays and Cohen demonstrated this is not provable within the ZF set theory using Godel’s theorem. Better said they found a form of Godel’s theorem that demonstrated the truth of the CH, but that it is unprovable. There exists a hierarchy of these transfinite numbers ?_n, and even ?_?, which leads to a new class of even more infinite numbers called least inaccessible cardinals. In fact the set theory guys have found several classes more infinite beyond that.

        This has some relationship to the indefinability of randomness, though rather tangentially. To be honest the business of transfinite numbers has little impact on physics, and I am not particularly much of a researcher on this area of mathematics.


      • bfmorris says

        So you’re saying, infinity exists as long as there are humans around to hypothesise it.

      • lcrowell says

        Infinity is not really a number, but a set or a set with ordinality and cardinality. The Cantor transfinite numbers are used to distinguish infinities (or sets that are non-finite) by ordinal and cardinal structures.

        Whether infinity exists, or any mathematical object exists, independent of a human mind gets into some issues with the philosophy of mathematics. I don’t tend to worry that greatly about these matters. I am not sure questions along these lines have a provable answer, and frankly I think these questions diverge too far from my principal interests.


    • Torbjörn Larsson says

      Thanks for noticing and responding.

      Yes, we can use more statistic machinery if we wish. But then we leave the tested model and replace it with a weaker, untested model.

      The only reason to do that would be if we know that there are dominant pathways for chemical evolution that are somehow radically different. Baring that, it isn’t a very good working hypothesis IMHO. Quite the contrary, many organic compounds found in meteorites et cetera are mundane and comparable to what metabolism uses here. (Amino acids et cetera.)

      • lcrowell says

        If these statistics are used to estimate priors, then the application of knowledge about possible chemical pathways can be used to update those priors. Until we find the big cahuna this is the best we can do.


    • andrew g says

      “If something is not absolutely forbidden by physical principles it is then mandatory. The lack of some physical impossibility for a state means this state exists in the set of possible states in the universe.”

      There is nothing in the laws of physics to prevent me being selected as captain of the England football team. I am 49, overweight, unfit and never played the game professionally, or at any great standard, but there is nothing to stop the manager picking my name out and asking me. So is this mandatory in some corner of the multi(?)verse? Remember, not only do I have to be selected, but the locals there also have to think this is completely logical. In fact there is a big campaign to get me reinstated when I am dropped after the next 20 games are lost.

      If not, what physical laws prevent these kinds of logical inconsistencies happening, and are there any examples in our universe? Religion? The existence of royalty as a system of government?

      • lcrowell says

        This situation might have to involve multiverse or many worlds considerations. However, while it is exceedingly unlikely that you will become a captain of an football team, or that I get drafted as quarterback for the New England Patriots, it is not impossible in the same sense as trying to exceed the speed of light.


  15. dwdeclare says

    it’s not so much that “we want to find a pinocchio living on some extrasolar planet” but that we want to find a bambi so we can murder his mother. humans are born soulless killers, lacking any empathy for the suffering of another, all so they can temporarily make a quick profit.

    let us not forget the wise words from the 29th scroll, 6th verse:

    “beware the beast man, for he is the devil’s pawn. alone among god’s primates, he kills for sport or lust or greed. yea, he will murder his brother to possess his brother’s land. let him not breed in great numbers, for he will make a desert of his home and yours. shun him; drive him back into his jungle lair, for he is the harbinger of death. “

    • Torbjörn Larsson says

      A bit too much Corny-elius for my taste.

      As for morals, we are born with it according to extensive research. Notably for amoralist theoreticians is also that precisely Homo is the peaceful ape, all the rest are natural born killers. (Even gorilla’s practice infanticide.)

  16. jjbreen says

    I had a Prof that had a great quote – All the equations in the world, are easily wrote and even quicker to be erased at the end of the day or week. Then a new equation will be devised. In the end they are all dust on an eraser.

    All the math equations about life out there are “dust on an eraser” until we actually find life.

    Then again, what do we mean? Life as INTELLIGENT or Life as Microbial? Either would be significant to be sure.

    But the odds of Intelligent Life? I think we are going to find it unanswered for yet a few 100 more so years …. The evidence as of yet is simply not there!

    • Torbjörn Larsson says

      Models are not “math equations” but testable hypotheses. That is something entirely different.

      Based on observations I claim that we know a whole lot on life, and actually enough to estimate likelihood. (Until more observations will evolve the area.)

      • jjbreen says

        “testable hypotheses” – Okay, so one planet (ours) is the only ‘test’ we have. We have no other planets for which to test this “hypothesis”. So there is a 50/50 chance that it is wrong or right ….. Time will tell. Heck, I’m not even sure we can call it a Hypothesis, to be honest, let alone a model.

        Because right now – the only evidence/proof we have of Intelligent Life is us.

  17. hionthemountain says

    The odds of other life in the universe are better than the possibility that there isn’t . . .

  18. andrew g says

    Turn the question round. If there is advanced life out there somewhere then we are the alien life that they might right now be searching for. On the principle that there is nothing special about us or our corner of the universe then it follows that any other beings must also be pretty much like us, watching tv, fighting wars, browsing their internet etc, or close equivalents.

    Since physical properties on these “Earth-like” planets are going to be similar, chemistry works the same way wherever you are – we have already detected organic molecules in deep space – once evolution gets going it is going to find the same solutions as it did on Earth. Eyes have evolved independently a dozen times, and wings more than once.

    So they’ll look just like us too, maybe with the odd extra toe here and there.

    • Torbjörn Larsson says

      That is pretty much what most biologists have concluded will _not_ happen.

      Eyes likely, legs perhaps – but traits like linguistically capable brains will happen once in a blue moo… planet. The elephant trunk only evolved once, the Homo brain only evolved once, the narwhal tooth only evolved once, eukaryotes and so the possibility of complex multicellulars only evolved once et cetera.

      If you ask biologists complex multicellulars will be exceedingly rare, and linguistic capability comparably rare among worlds with complex multicellulars.

    • bfmorris says

      Eyes have their beginnings from sight specific control genes that are present in all life, as I understand it.

      andrew g wrote: ” On the principle that there is nothing special about us or our corner of the
      universe ”

      ‘Us’ looks special to me.
      I think a discussion of what constitutes special, would be interesting. Is uniqueness a component of special? If a US coin mint had struck only one of a certain gold coin or even a few of them due to whatever circumstances, are not those coins then considered ‘special’ and sought after by collectors? If there is only one andrew g in the universe, no other made exactly like him, it seems that single issue of andrew g is quite special.

  19. Jeremy says

    If you think that the odds are in favor of their not being other intelligent life then you need an MRI. Seriously.

  20. DNA Nebula, as I prefer to call it, might have been formed and shaped under the influence of gravity. Biomolecule DNA, the blueprint of life, also might have been formed and shaped under the influence of gravity.The following equation derived by me strongly suggests the correlation between DNA and our Solar System, thus indicating the influence of gravity in the formation and shaping of DNA.

    64 – As 339
    —————– = —————
    20 107.65

    Where, 64 = Number of codons
    20 = Number of amino acids
    As = Astromolecular constant i.e. 1.013, derived during the present

    339 = Number of disks of Sun to measure its apparent path along the ecliptic in
    Celestial sphere between the two equinoxes
    107.65 = Average distance of the Sun in terms of its own diameter

    All living organisms on the earth share the same 64 codons and 20 amino acids.

    For details please go on the Link:

  21. TheMatrixDNA says

    Alternative form of life? We can try another approach. Today nobody could accept that the cellular organelles are forms of life. because they are part od cell system. But… if the symbiotic hypothesis of Margullis is right? Ribosome, Mitochondria, chloroplasts, till the nucleolus were micro-organisms? If so, each one could evolve to specific life form? Today nobody could accept that astronomic bodies are life forms. Because their constitution seems so single and they belongs to stellar and galactic systems.

    The formation of the first cell system was different from the formation of modern cells. The cells does not need those millions years of abiogeneses because they learned to replicate themselves. If the formation of the first galactic system was different also from the formation of modern galaxies? I mean, the first galaxy was formed by symbioses?

    There is a natural mechanism that could be the solution for the process of symbioses for both, cells and galaxies: life cycle. If a different life form – one that seems to us a inanimated object or/and non-able to replicate – is under this mechanism, the object will be transformed into several different shapes, like a human body under this mechanism shows the forms of blastulae, embryo, baby, adult, etc. So, any molecular complex compound like a ribosome, under this mechanism could be transformed into mitochondria, cloroplast, all shapes of organelles. it is easy for seeing this if we think the different shapes of anumal specie under evolution, from reptiles to fish to mammals. Now suppose that before galaxies and even stellar systems origins, there were a unique kind of astronomical body, but, under the process of life cycle. Its transformations could be from planets to pulsars to stars to quasars, black holes, etc. Since that there is a conexion link between two sequencial shapes of any individual, this conexion is the responsible for symbiosis.

    It is weird to think that a kind of inanimated natural object could be under the process of life cycle. But there is a possibility, and it came from natural light. The electomagnetic spectrum of light shows that any laight ray or wave has seven diffferent frequencies. it means seven different speed of vibrations. Applied over a natural object, dense enough that the light can not escape, but it is not destroyed, each kind of vibration could perform different effects over that object. Maybe a light wave has the code for life, if the seven different vibrations can generate seven different shapes of a unique object. So, it is not weird at all.

    Now, think that the radiation of light from the Sun creates seven different fields of vibration around it. Seven different orbital fields. There is only those two intermediates orbital suited for the seeds of life being nurtured, because the initial ones are too much rapid and the last ones are too much slow. The planets in these orbitals are Earth, Mars, maybe Venus? Now suppose that a star is like an onion, each level is about each stage of its formation. It should means that the Earth surface receipts seven kind of photons, each one as bit of information of a shape of a life cycle. In another words, all seven shapes of photons together are the seed of life. The Earth nucleus must have at least the initial 50% of those bits, which reaches the surface through volcanoes, ocean vents, etc. Then we have the appropriate land for the seeds evolving. And the process of fecundation is like our sexual process; half of information coming from the sun, another half coming from Earth.

    Finally, which were the previous information for the first biological life? When I calculated what could happen to an initial astronomical body under the process of life cycle because it does not permit the escape of light, I got the existent another known six shapes. Those seven kind of bodies could be linked by the invisible connection of time, like a human teenage can be linked to its adult shape. But, doing it my models showed that the seven astronomic bodies are aligned like a circuit of a system, and, surprising, the system has the same shape of a lateral pair of nucleotides, the fundamental bit of information for RNA and DNA. So, the previous information for the first biological life form is the information about astronomical systems, whose that really created life inside them.

    Researchers has experimented all possibilities of miligram of RNA and not got a life form. What is missing in those RNA? The work of those photons? Inside terrestrial atoms they can work like a religion can work a human brain: changing the atoms normal behavior for to build a copy of the celestial system they came from. At my website there are the models of Matrix/DNA formula, the astronomical system under the force of life cycles, the electromagnetic spectrum as the code for life, etc. It could be everything wrong, but, I think is good food for thought in different ways like we wull need for to recognize different alternatives life forms.

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