A while ago, I posted an article called Alien life, in which I asked the question whether people thought life might exist on any of the multitude of exoplanets being discovered. I have since learned some stuff I didn’t know before, which has altered my own views. Some of the information comes from a book called Rare Earth, and some of it from other research I am doing. I can’t in this space include all this stuff, but I will summarize the key points.
- On Earth, forms of bacteria and Archea (single celled life forms) have been found that live in super-hot (hotter than boiling water) environments, in rocks, in ice, in sulfur springs, deep under the Earth’s core, in the absence of light or oxygen, and so on. These “extremeophiles”, suggest that life could likely exist in many other environments other than the relatively Earth like one we know,
- On the other hand, animals require very special conditions, including oxygen, water, moderate temps, moderate pressure, and so on. Before you object that we can’t really know about what is possible, I should say that this conclusion is based on general principles of chemistry and physics.
- The first life appears on Earth in the fossil record almost 4 billion years ago. This single cell life form appears to have been DNA based, and able to do photosynthesis. It is possible that very little time elapsed between the cooling of the new born Earth and appearance of pretty sophisticated living cells. It is highly unlikely that spontaneous chemical evolution on Earth could explain the origin of terrestrial life in such a short period of time, and raises the long held hypothesis that life arrived on Earth on a comet or asteroid to a higher level of probability. Especially in light of point 1.
- The Earth is a very unusual planet in many ways, in relation to its size, shape, temperature, atmosphere, magnetic field, period and shape of rotation, degree of large object impacts, (because of the presence of nearby gas giants, Jupiter and Saturn), the position of its star (the Sun) in the Galaxy, the fact that its star is not a binary or higher star system, its geological history and structure, including plate tectonics, its stable but slightly variable climate, size of its moon, and a few other things, all of which turn out to be essential for the evolution of larger than microscopic, multicelled animals. In other words the Earth may be, even in a galaxy filled with millions of planets and moons, hundreds of thousands of which are likely to harbor simple life forms, the only place where animals, including conscious, intelligent ones, like us (or at least some of us) can exist.
So, this could mean that while we might actually find living microorganisms in lots of places, including Mars, Europa, and in many other solar systems, we will not find any other civilizations, aliens, or anything else with a nervous system, let alone a desire to conquer or communicate.
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Comments: 61
How will this affect sci-fi, one wonders? The earlier understanding that even if there are other intelligent species out there, the distances involved would prevent us from ever meeting them didn't put much of a damper on extraterrestrial imagination, it seems.
See below for my thoughts on this.
Indeed, our version of civilization and our particular planetary configuration may be "special," which might make the notion of intelligent//sentient life a "great rarity."
However, I also subscribe to the effect very large numbers have on "expected outcomes." The odds of YOU winning the Powerball lottery this week are almost impossibly tiny. However, when 300 million tickets are sold, the odd that SOMEone wins the Powerball rises to almost 100%. Along those lines, the likelihood that any given planet we examine supports life is remote... but given the size of the universe (an estimated 9 × 10^21 stars in the OBSERVABLE universe), the likelihood that hundreds of thousands of planets with sentient lifeforms exist seems pretty high. Even if we assume that "something like" planet Earth is a 1-in-one QUADRILLION event (1-in-1,000,000,000,000,000) we'd still end up with nine MILLION "earth-like" environments.
Whether we (or they) will ever find each other and make contact? That just adds another layer of probabilities...
Personally, I don't believe the odds are even that long... in part because we have a very human-centric perception of what constitutes "intelligent life," limited by our current knowledge of physics. 500 years from now, we will have PROVED things that today look like "pure science fiction," just like two people talking to each other on cell phones in the middle of a crowd of 16th century peasants would seem (to them) like witchcraft.
First I am only considering this galaxy, because travel between galaxies will probably never be possible, even with wormholes, and despite the beloved "hyperspace, speed warps" etc. of sci fi. And time wont help, because the universe is getting more expansive every minute, so the other galaxies are getting even further away with time.
There may very well be all kinds of smart aliens in the universe, but we will never know about them, not they about us, because given the upper speed limit of light, by the time we could make any sort of contact, one or the other of us would probably be long gone.
So that lowers the odds by several hundred billion fold. Within the Galaxy, we need to rule out the majority of star systems which are double or triple or higher, because all planets in such systems will follow very irregular orbits. That means that conditions on the planet will vary greatly, and not allow for the stability required for complex life forms to arise.
Of those that are left, the number of planets good for animals, meaning where animal life is even possible to evolve, might be pretty small. More data needed.
The proteins needed for life have very complex molecules. The chance of even a simple protein molecule forming at random in an "organic soup" has been calculated to be only one in 10 raised to the 113th power (1 followed by 113 zeros). The number 10 raised to the 113th power is larger than the estimated total number of all the atoms in the universe
Five histones are involved in DNA (histones are thought to be involved in governing the activity of genes). The chance of forming even the simplest of these histones is said to be one in 20 raised to the 100th power, another number "larger than the total of all the atoms in all the stars and galaxies visible in the largest astronomical telescopes.”
Second, as I have commented below, Without intending to and even though he refuses to recognize that he did, Dr. Robert Shapiro has killed and buried the notion of abiogenesis.
For proteins to form from long chain polymerization of amino acids in the correct sequence and to achieve the correct three dimension shape so that they will function requires ribosomes. However ribosomes are composed of protein and RNA, so which came first Peter, the ribosome or the protein?
Neil deGrasse Tyson and other astrophysicists/experts have written and lectured about our humanity prejudicing our expectations of alien life. Have you read up on those? The odds are that if some form of life happened here on Earth, it probably happened again, somewhere else, but the likelihood of Earth humans to find/detect it are slim in the first place, and then limited by our humanity.
Basically, the known universe as we have been able to grasp it in our little carbon-based brains leads us to really limit definitions of what we are willing to call "alien life". We are pretty egotistical in applying our definitions to the universe's potential. What if life exists in the electromagnetic form of energy where no bodies are needed? I think the great science fiction writers, who allow for any and all definitions of life to be explored, have more freedom to wonder. The scientists are limited by the need for facts that the fiction writers can disregard.
I think it's all worth wondering about, even if the answers will never be determined.
Tyson is a brilliant astronomer and cosmologist. Biology, not so much. I think that life will always be chemical and not (at least initially) composed of energy fields, etc for the following reason. There is no single good definition of life, and there are some entities that seem to be between life and non life (viruses). But what life certainly seems must entail is a high degree of structural and functional complexity. Chemistry allows this. And carbon is the only chemical element that has the versatility to form an almost infinite number of molecules, but simple, and extremely complex (the structure of life). Carbon based chemistry is also the only type that allows for very complex reactions, (the function of life).
So if life is always chemical in nature, nothing compares to carbon, and nothing comes remotely close. What about non physical life, as in the EM energy you suggest? I honestly have no idea. If such fields (perhaps much more complex than the ones we are familiar with) exist and have some form of transcendent character that we might think of as living, than you are right, we might never detect them.
There could after all be many definitions of life. By some definitions the Gaia idea says that the Earth is alive. Is Gather alive? Im not joking. Perhaps we are creating a new form of life with electronic networks, and computers. Yes Sci fi is great for wondering and imagining.
Here's a concise explanation of why carbon is unique in being able to form an immensely large variety of complex molecules (including why silicon is close but no cigar).
Oh, you mean this one?
PS: Why were/are you in a dungeon?
First, to all who wish to criticize the fact that Sy limits this to carbon based chemical life, remember that the very fact that complex unicellular life was in our oceans almost as soon as we got an ocean amounts to proof that if did not happen spontaneously; it is unreasonable to conclude that is did.
Without intending to and even though he refuses to recognize that he did, Dr. Robert Shapiro has killed and buried the notion of abiogenesis.
The possibility that life might have come here on an asteroid or comet, doesnt rule out abiogenesis, just that it happened somewhere else. Of course I agree with you, Dennis, but at this point that is based on other than purely scientific grounds, which I dont want to get into yet (until it is inevitably raised by others).
If you accept evolution as the sole pathway for life then once there is a single cell it most evolve to higher life forms. If you subsribe to God creating man then you must accept that if God wants other life out among the stars then it will exist, and it not then it will only be here on earth or will be propogated from here.
As best I can tell science has shown that single cell life does exist out among the stars and yet we have it has not shown that a higher life forms out there.
Science has not yet shown that single life exists among the stars, although most scientists seem to think so. No actual evidence yet.
Your point that once a single cell exists, it must evolve to higher forms, may or may not be true. It took between 0 and 3 hundred million years for the first cell to form. It took much much longer (about 2 billion years or 5-10 times longer) for the first multicelled animal to appear. And the conditions for that to happen had to be just right, and far more stringent that for original life forms.
Animals require a very efficient energy consumption and transformation system. Basic chemistry tells us that the most efficient fuel for chemical energy use is oxygen. Living cells first emitted oxygen and then had to adapt to using oxygen as an energy source. If oxygen had never been produced by the original algae, there would have been no animal life.
If evolution is a proven, at least to the satifaction of earth science (they seem to fight very hard against intelligent design) then why would it not apply throughout the cosmos. If the building blocks are there then why should they not expect a singel cell and once a single cell then evolution would force higher forms of life.
If we are to believe in the randomness of the universe shold we expect that when building blocks came into existance on earth they could/would have been found elsewhere and a similar path be followed that the evolutionists says in proven on earth? This should all lead to higher forms of life elsewhere in the universe. And as you have pointed out we have yet to have that proof.
I must admit I am one that believes in God's design which allows for there only being life on earth.
Evolution seems to suggest that there has to be 'alien' life, while design creation allows for there not being such life.
"the Earth may be, even in a galaxy filled with millions of planets and moons, hundreds of thousands of which are likely to harbor simple life forms, the only place where animals, including conscious, intelligent ones, like us" ..."we will not find any other civilizations, aliens, or anything else with a nervous system, let alone a desire to conquer"...
It is my beliefs, from my studies, that many humans cannot comprehend past their nose. It is my belief that the Spiritual realms far exceed the present and pasts in so much as the so called ALIENS; are those who wouldn't be held back by the dictates of the human mind.
Generations of the ancients left their road maps to the futures; carved in stone and ideologies of their visions of paradise in the higher plains. If you are talking ONLY, about the specifics of the expansions of micro organisms, then, I would have to agree at this point; within our reaches of knowledge we ARE held back to the earthly plains.
I have seen much farther… as I believed, and found the mind CAN CARRY you to other dimensions. Examples of these are in the experiments of the past by various governments using LSD and the ancients with their mind altering herbs. People learned the mind was capable of seeing farther than…AGAIN, “the dictates of human kind!”
One good book goes into many of these plains… 2012 The Return of Quetzalcoatl, which has many different references to those who have ventured outside the box. But, is as it has always been; if you can’t see, touch, or smell it… IT doesn’t exist? I guess that might be the all encumbering alien? LOL
Thank you for your submission to "Faithful Seekers my friend! Your article is FEATURED!
As such, the likelihood that man on Earth will ever discover a civilization beyond Earth is probably miniscule.
However, there are so many systems in so many galaxies that the likelihood that nowhere else, ever, intelligent life exists, existed or will exist outside our planet is also miniscule.
I agree that it seems likely that organic molecules arrive on planets carried on space detritus, but I don't know about the likelihood that it would have qualified as life when it got here. I just have great difficulty accepting that even Archaea-like life developed in atmosphereless, waterless space. I think it's more likely that the "building blocks" may have been created in the chemical stew of dust and gas clouds assaulted by the energies of stars dying and being born, and were then transported to places where other elements and compounds could be found in large quantity.
In any case, Dennis' "more than all the electrons in all the atoms, etc." statistical hyperbole aside, in my view the greatest argument for abiogenesis having occurred is that it demonstrably did. It make a helluva lot more sense to me than "adeiogenesis." The idea that a god created itself out of whole cloth in a pre-existence time of no time, no space and no place, and then created a universe as vast as this one to give himself a place to be, is far less possible than Dennis' argument makes abiogenesis to be.
I would like to believe that there are other intelligent beings out there, and I can even imagine ways in which star-cultures might develop and meet each other. But I have great trouble 'believing' things for which evidence is unavailable... pro or con. So my position is that I hope we're not alone, but it will cut no immediate ice if we are. I'll keep running my Seti-bot computer, and we'll just see.
Just bear in mind that advanced civilizations moving about the cosmos at measurable fractions of "C" may explain dark matter. After all, as physical bodies approach the velocity of light, they approach infinity in mass, and time slows to near zero for them. It wouldn't take much at .99 "C" to build a helluva lot of relativistic mass, I'm thinking. It has also been suggested that some of the earliest galaxies are moving away from the inner universe at speeds in excess of "C." Dunno how that's possible, but it was a serious suggestion not long ago, and what that does to relativistic mass when you start with the mass of a galaxy, I'll be dogged if I know.
I was wondering how long it would take to bring God in. I did predict it would be from an atheist, because for some odd reason, it always is. My view is that when we start thinking about what happened before the singularity that produced space time, matter and energy, God makes about as much sense as any other idea.
Beings that create universes have the attributes of gods, be they so designated or not. Therefore, they ARE gods. As such, they are far too complex themselves for their spontaneous or "self-" creation to make "...about as much sense as any other idea." It makes more sense to me to agree that the singularity was a hyper-compressed point of near-infinite energy in that no time, no space, no place, and that it destabilized and expanded explosively. The physics of non-homogeneous energy expansion and compression eventually explains the appearance of matter and its rise in complexity, as well as the recurring chemistry in space.
God ain't necessary for "creation." I don't think such being, since it wasn't necessary, came into existence. I don't think it could have.
"Intelligent life?" That I'm less sure of. Dinosaurs had 200 million years to evolve true intelligence, and there's no evidence that they did. Mammals were around for most of that time, but they didn't truly begin to smarten up until a goodly time AFTER the non-bird dinos had jumped the Megalodon. True self-aware intelligence is less than ten million out of four BILLION years old. Don't know how often that's gonna happen... whatever the giant planet protective situation may be.
My last paragraph? A very old Science Fiction short story (the writer gave up at the end and went mystical) triggered that idea, and it's been percolating ever since. It also gave me the idea that Time, besides being a dimension, might also be a force, like one of the strong or weak forces. I would tend to either ascribe it "weak" characteristics, or make it a third class entirely. This would mimic, at some level, the photon (ray, particle, wave - all in one).
Isn't that circular logic Chuck? It has not been demonstrated that it did. For an atheist, the fact that life exists becomes the proof that abiogenesis occurred. The atheist must then rely on faith to maintain the belief. When I point out that complex unicellular life was in our oceans almost as soon as we got an ocean and when I indicate that Robert Shapiro has successfully demonstrated that there was no cyotsine or uracil on the pre-biotic earth, your reply is simply that I am using argument of ignorance and you have clearly stated already that one day, a scientist will arrive at the explanation.
My argument is not argument of ignorance, but this is:
"The idea that a god created itself out of whole cloth in a pre-existence time of no time, no space and no place, and then created a universe as vast as this one to give himself a place to be, is far less possible than Dennis' argument makes abiogenesis to be."
Not only is it argument of ignorance, it misrepresents my belief. I am not of the opinion that God "created a universe as vast as this one to give himself a place to be". Why does He even have to be in the universe? It may not even be able to contain Him. 1 Kings 8:27 says that "The heavens, yes, the heaven of the heavens, themselves cannot contain" Him.
Remember years ago, I stated that one of the assumption on which I base my belief system is that this universe in not all of existence. I have also stated more than once that there is insufficient time within this universe for it to be reasonable to insist that degree of complexity we currently see came about spontaneously. However, outside the universe, we are working with infinity. "When you are working with infinity, even the improbable becomes probable" (Michio Kaku)
They are indeed receding from each other (there is no "center") at "warp speed." The diameter of the universe, after 13.7B years, is currently about 45B LY.
Regarding relativistic mass, the term "relativistic" points to the fact that the increased mass in question is measured from the frame of the moving object. Energy-mass is conserved over acceleration.
I'm sure Mr. Spock never actually said anything like that but your article does raise the question "what do we mean by life."
I worked out once how long it would take us to reach the nearest planet that might possibly support life forms similar to those on earth travelling (a) in the fastest spacecraft we currently have and (b) in a vehicle that could travel at one tenth the speed of light.
Even at a tenth the speed of light, which we cannot even envisage with current technologies, the trip was unrealistic and given the chances of finding nothing there certainly there is little point in thinking about such projects.
Recently, in response to someone banging the 'psychology as science' drum I asked for a scientific definition of the human mind (and got one of the brain as was anticipated.) I'm convinced that if we ever come to understand what makes us the creatures we are, what gives us human consciousness, we will learn more about the universe by looking wthin ourselves than by star gazing. Buddhist and Hindu beliefs offer a lot of insight and even Christianity points in the right direction.
Doctor Who's TARDIS is tiny on the outside but infinite (in fact it contains an infinity of infinities) inside. The metaphor is, as the saying goes, not rocket science.
I agree that there is little possibility of finding it using our current methods of propulsion.
It has been mentioned above that the universe's rate of expansion makes the travel even more difficult, I am sort of imagining this in a "by the time we get there, there will be gone" kind of way. I like to think that eventually mankind will be able to use other means of exploration through parallel universes or something, but I read a lot of science fiction I suppose.
Great post and very interesting, knowledgeable responses. Love it.
More later...?
This might come as a shock to you, but I no longer believe in RNA world. Not because it doesnt make sense, it does. There is no other way to expain spontaneous abiogenesis on Earth. Catalytic replicators, such as ribozymes are the only feasible intermediate step between nothing and coding DNA.
BUT, in addition to Dennis' oft cited and correct assertion that making RNA from scratch on this planet, just wasnt possible, due to the scaricity and lability of cytosine, there wasnt enough time. There is evidence of photosynthesis 4 billion years ago, when the Earth had barely cooled below the boiling point.
Anyway, back to the article, one issue that I dont think they address very well is that Mg was also plentiful on early Earth. The switch from Fe to Mg, after oxidation must have happened much much later than RNA world (assuming it existed) since the oxygenation event was a billion years after the origin of DNA life. ITs possible, I suppose that Fe remained associated with ribosomes (which evolved from ribozymes) and then only those cells that had converted to Mg survived the O2 event. Anyway, nice article and thanks for the link. And stop working so hard; you are needed here on Gather.
A good example might be cytosine. That a proposed abiotic mechanism for cytosine production requires both high temperatures and pressures suggests only that the process may have taken place deep under the (then iron-rich) oceans near hydrothermal vents. The raw-materials for life may have been extremely abundant on the early Earth, and the lack of current explanations for specific processes may merely reflect the extreme differences between the early Earth's nature and its present-day form.
In fact, I would assert that the very nature of “life†itself may have changed along with the earth's environment, and I think the “iron mediated RNA folding†article suggests that this has been the case. Early life on Earth might have included some proto-organic chemistries that we no longer see, perhaps even crystalline frameworks or geothermally-powered metabolisms. This may explain at least some of the seemingly arbitrary aspects of life as we know it now, such as the chirality of the Earth's organic chemistry, or the particular choices of nucleobases in RNA and the replacement of Uracil with Thymine in DNA.
Perhaps this even provides an answer to the conundrum of the absence of cytosine in an pre-biotic environment, in that it may not have been cytosine at all that formed the first proto-RNA. Cytosine may simply have been a convenient, later biochemical replacement. The parameters for the creation of life may thus be much broader than we expect, and functional substitutions may take place in organic chemistry as a planet evolves. What exists as life on a planet now may bear only a limited bio-chemical resemblance to that which gave it a start.
That still doesn't answer the question of whether or not those initial conditions are common or rare throughout the universe (especially since we don't really know what they were). But it does indicate that we may be looking up blind alleys in our search for places where life has at least been able to get a start.
I knew it was a good idea to post this. Thanks for the thoughts.
As an engineer (and an ISTP, "mechanic" type personality), I'm inclined to believe what I can measure...at least to the extent that I have a "view" and an understanding of what to look for. In that regard, my response to Fermi is that stable technological civilizations are apparently more rare than would allow the size and age of the universe to give such civilizations overlapping domains. In effect, there may be other technological civilizations in the universe, but we are functionally alone.
The way I see it, the only reasonable alternative is that we don't know what to look for. Perhaps aliens are all around, but we just don't recognize them (too small, too fast or too slow, or behaving in a way we don't recognize as intelligence...)? Or perhaps technological civilizations reach a point where exploration is a moot point, and we just don't recognize their energy signatures?
The Eerie Silence, by the SETI researcher and Chair of the SETI Post-Detection Taskgroup, Paul Davies, addresses all of these speculations. He concludes that there really doesn't exist enough data to rule out any of them. We could be alone, or we may just be too ignorant to see otherwise. Personally, I like to believe the latter...but my nagging suspicion is that we are (as your post suggests) a fluke in the numbers.
My caveat here is that I don't believe that a stable technological civilization will remain biological. This is right down my line of work -- efficient technological evolution favors versatility, energy-efficiency, and "ruggedization." Apply this to a highly-advanced civilization, and you encounter compact, redundantly-interconnected machine-intelligence, controlling whatever apparatus is minimally necessary for a function. As to what functions would be performed by such an advanced "civilization," that might be a clue as to what to look for.
How to describe what we ignore? To start even a description we do need some point of reference as we cannot describe what we ignore. And what is being discovered can very not suffer from the Universe's forces and be completely different from any one or anything we know.
As far as evolution from what we call inert material into a material able to reproduce itself (on Earth or somewhere else), a material able to go through several transformations during some period of life, it doesn't seem impossible as far as I am concerned. But, again, we are here victims of entropy. IMO, light is a fantastic source of energy we still cannot really capture as per example the cosmic rays. We receive a lot of hem and still we ignore their influence, if any.