Sunday, October 11, 2009

What Will They Be Like? : Chemistry

Who is the "they" in the title? This is a post about the "they" who might be traveling the Universe in technologies of various sorts and might come here to Earth. It is not about any "theys" who don't come in physical technologies. It's not about "theys" who have been artificially constructed by other "theys" elsewhere or in the past. It's about "theys" who have evolved on planets over millennia and have, therefore, long histories. This post is one of several which will try to explore what science has to say about advanced life in the universe. We start with chemistry. You can find all manner of science fantasy commentary about life based on every conceivable thing. It is all entertaining. It also has essentially no grounds for being taken seriously. The picture on the right says "millions of possibilities". On a number of things about our universe that is true. There may well be millions of stars having inhabitable planets. There may be millions of civilizations more advanced technically than we are. But there are not millions of biochemical systems. In fact, at a gross level of comparison, there may be only one. That is the CHON-P elemental system. Why? Isn't this a failure of creativity? Perhaps. But it is not a "parochial" bias as some would wish to claim. Consider these statements: a). a living organism must be at least a little complex. It must be able to maintain its existence in the face of damage [self-maintenance]. It must be able to pass on the information which gives the recipes for making itself [reproduction]. It must be able to alter its information without necessarily terminating itself [potential to "mutate" and evolve]. Simple atoms and molecules don't have the wherewithall to do this. b). a living organism therefore must have a complex physical system which can do these "living" tasks and have developed from the non-living environment preceding it. c). It must be able to control a microenvironment wherein simple pieces can effectively be built into more complex ones. d). the available pieces for use in this "life" endeavor are atoms/molecules/chemicals. What chemicals have the qualities necessary to pull this off?-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Science fantasy writers have "engineered" a variety of odd life forms for their books. All, even of them, realize that you have to string atoms together in structures of significant length and shape to achieve the chemical powers necessary to create the behaviors of Life. Because of that, they, if they're paying any attention at all, know that they have only two atoms which can combine in such long structures: Carbon and Silicon. It's not imaginative, but it IS the law. So, silicon creatures arise! But they won't...not really. I take this news as sadly as anyone. Diversity is more fun. But it ain't gonna happen. Why not? Note these few facts, among many: 1). the carbon-carbon bond is twice as strong as the silicon-silicon bond. Well, who cares? Mother Nature does. These chemicals have to come together as very small molecules in chancey inefficient ways back in the days when there was no life at all and the molecules were just blundering about occasionally bashing into one another and then making a bond. Then they had to "hang tough" until the next lucky "bump-into" occurred in just the right way and a yet bigger molecule was formed. And on, and on. You need some stability to survive. Carbon is twice as stable with its bonding. 2).Generally speaking you want interactions to take place so that you [the forming molecule] can grow more complicated. In the Universe, and in the Solar System, and in the atmospheres of primitive Earths, Carbon is ten times more abundant than silicon. When Carbon connects to the most abundant atom [hydrogen] it forms Methane and happily goes about in the atmosphere and even readily dissolves in water. Silicon with hydrogen is unstable in water. Carbon with oxygen makes Carbon Dioxide, a useful chemical and dissolving in water. Silicon with oxygen makes, basically, sand. 3). One can go on and on with these chemical facts. The story is simply: carbon is so superior to silicon in almost any measure that even on the surface of the planet, where silicon outnumbers carbon by 600 to one, life paid no attention to silicon at all. Life, for these and many other basic science reasons, is going to be made of long and diverse chains of carbon atoms with other atoms which react well with carbon [and are reasonably plentiful] attached to those chains. In this sense, all advanced chemically-evolved life forms will have the same base. -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
The primitive times of every forming planet will be more violent than [probably] any other time in its existence by a great deal. There should be a great "rain" of materials from the original solar cloud bombarding the surface. Once the temperatures cool down, the hot atmospheres should give up most of its water in a deluge that Noah wants no part of. The availability of energy is great and protolife chemicals must be tough enough to take it. Rough as this was, our Earth formed early life almost immediately--entirely based on Carbon chains. Bernard Oliver, chief of NASA'sSETI program said: " On Earth, life began almost as soon as the planet was cool enough to form seas. If this is typical, there may be as many as ten billion Earth-like planets in our Milky Way alone. Today we contemplate a universe teeming with life." I once had the privilege of studying with Michael Papagiannis [one of the most widely educated and sensible of the scientists hoping to detect extraterrestrial life---he also was not opposed to the idea of ET in UFOs, by the way]. We followed the steps-to-life from molecules to cells and beyond, using the best data of the sciences. He said this in conclusion: "If many other advanced civilizations were to have evolved on suitable planets around other stars of our galaxy, it is not too chauvinistic to believe that their life chemistries will also be based on carbon and water and that their long biological evolution will slowly convert their atmospheres to have a considerable amount of free oxygen..." And, given the laws of chemistry, the way that the essential chemicals of life will be put together and used, may be stunningly similar. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Scoffers and fantasizers complain that all these chemical claims are based upon just one situation, our own. Such a brainless argument [excuse me, but that's all it is] ignores the relevance of all of chemical science, the laws of which are hardly going to be different on each different planet. But the argument isn't even true anyway. We have several other points of data to study. These are the deepspace meteorites--rocks landing on Earth whose isotope ratios show that they are not part of our own solar system and therefore originate from distant, different areas of the galaxy. [I'm staring at a piece of one of them as I type, the Murchison for those in the know about these things, and it's rather irrationally awesome to contemplate]. These extraterrestrial non-living visitors are the "carbonaceous chondrites" and they contain a significant amount of carbon based molecules which were made "somewhere else". When you get them into the lab and find out their structure, there are lots of long chain simple carbon strings, sort of like shortish oils, but there are also wonders. Those wonders are the same amino acid molecules that we and all Earth life are made of [that is the same molecules which make up our proteins]. Nature had a lot of structures that it [in fantasy] could have made. It did not. It "chose", by law, to make the same chemicals that we are made of. Even more surprising to the analysts, they found small amounts of our "information chemicals", the "code word" bases used by DNA, in these ET-stones as well. We are not dealing with chemical chance here. We are dealing with chemical law. Not as much fun for the fantasizer but a lot better science. And, it doesn't stop us from curling up with a whopping good book which we efficiently read with our CHON-P chemical-based eyeballs.


  1. Carbon is best for solid/liquid phase life to evolve naturally, but perhaps there are different temperature / pressure / elemental abundance situations where silicon's potential energy landscape is more favorable for sustaining rather than starting life than carbon is. It is hard to see how such life could get started naturally, but once started, there are certainly environments where silicon could be self-sustaining. A naturally-evolved species might occasionally have reason to create silicon life just as we work with genetic algorithms and think about creating potentially self-reproducing inorganic molecular nanotechnology.

    But the idea that solid/liquid phase life is all that is possible may itself be a parochial view. Plasma constitutes nearly all of the visible universe - and much of the rest as well - and plasma can give rise to and sustain complex organizations perhaps even better than solids and liquids.

    which shows that plasma can organize into what appear like feeding, growing, self-reproducing, communicating cellular structures. Also see about simulations of dust plasma crystals with helical or double-helical form which can store and copy information.

  2. The basis for the post excluded something that "somebody else" made. I am open minded enough to imagine an already highly developed intelligence figuring out almost anything---but that just puts the query off to one species back with no original answer. As far as Silicon life developing on its own: I still read that the odds, regardless of the extreme conditions imagined, are against it happening. Reasons? We need true complexity in the macromolecules. Silicon chains are very limited --essentially to linear structures--carbon can go several ways off the same atom, thereby facilitating three dimensionality at the molecular level, allowing structured nests for favorable force environments for metabolism to take place, and any other useful reaction. Also, the basis of the post was to ask about "who" would get off a technological artifact on a visit--which is what is relevant to the UFO question. Silicon microlife, if any, is not a good candidate for managing and controlling a chemical-science environment necessary to advance technology in metals, electricity, polymers, etc to ultimately create that craft. As regards plasmas, I've seen nothing remotely convincing as to long-term stability of complex organization necessary for slow evolutionary advancement of simplicity to complex intelligence. I can be wrong on any of this, but my years in the history of science show me that certain sorts of speculators at intervals toss out interesting ideas because they are fun and if you track them you find that a month later and well beyond they've developed nowhere. This happens at regular intervals in the New Scientist, which I like and subscribe to, apparently because it sounds great on the cover and sells magazines. But my ears are still open.

  3. Mike,

    As you noted, the chemistry related to the development of life is obeying a law and hence the argument that 'life on this earth represents a single sample and therefore should not be used to draw conclusions about life in the rest of the universe', is not valid. I have never liked this arguement, whether one is discussing the uniqueness of life, development of earth-like planets, etc. It rings too much of the pre-Copernicus beliefs that the Earth is at the center of the Universe and that we are unique! The argument attempts to use statistical sampling techniques of a population's characteristics when the real question is not about the characteristics of a population sample, but whether there are any other samples at all. Let me explain my rambling.

    The argument is valid if ,for example, one is attempting to determine the quality of a product by examining and testing samples or if one seeks to determine the genetic results of cross-breeding pea plants. In these situations there is a basic knowledge of the potential overall characteristics of the population and it therefore follows that statistical sampling is necessary. But does that apply when we know nothing of the characteristics of the samples in a population, because we have a sample of only one? We are not trying to determine if the sample's characteristics are different from a given population; only whether there are more samples to even create a population from which to work. A sample of one is not a question for statistics.

    When the first pulsar was discovered in space in 1967 emitting quick radio pulses, we had no theories yet, just the fact of the existence of this unique object that we decided to call a pulsar. (I am not discussing the likelihood of pulsars once the physics behind them was understood, only their likelihood when we knew nothing of the law of physics behind them.) Is it more logical to assume that no other pulsars exist unless we find another one or is it more logical to assume that we did not find a unique object in the universe? I'm a betting man and I will always side with the latter.

    By the way...I really enjoy reading your posts Mike, even if I don't respond to them very often. I can't seem to finish one before it has sent me off researching some idea that you have cast forth.

  4. My friend, the universe is a very big place as you allude. The odds of there being PROFOUNDLY UNIQUE things in it are just about zero, one would surmise. [as you are saying here, to my applause]. Wouldn't we think that this awesome context alone would put a stop to the "Race-to-Denial" that so permeates our culture and consciousnesses? That we can not open up even a little to the hinted mysteries that we're talking about here, is a statement about ourselves and not our universe, and we should be ashamed.



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