Scientists identify Earth-like exoplanets

Scientists identify exoplanets where life could develop as it did on Earth

Scientists have identified a group of planets outside our solar system where the same chemical conditions that may have led to life on Earth exist.

The researchers, from the University of Cambridge and the Medical Research Council Laboratory of Molecular Biology (MRC LMB), found that the chances for life to develop on the surface of a rocky planet like Earth are connected to the type and strength of light given off by its host star.

Their study, published in the journal Science Advances, proposes that stars which give off sufficient ultraviolet (UV) light could kick-start life on their orbiting planets in the same way it likely developed on Earth, where the UV light powers a series of chemical reactions that produce the building blocks of life.

The researchers have identified a range of planets where the UV light from their host star is sufficient to allow these chemical reactions to take place, and that lie within the habitable range where liquid water can exist on the planet’s surface.

“This work allows us to narrow down the best places to search for life,” said Dr Paul Rimmer, a postdoctoral researcher with a joint affiliation at Cambridge’s Cavendish Laboratory and the MRC LMB, and the paper’s first author. “It brings us just a little bit closer to addressing the question of whether we are alone in the universe.”

The new paper is the result of an ongoing collaboration between the Cavendish Laboratory and the MRC LMB, bringing together organic chemistry and exoplanet research. It builds on the work of Professor John Sutherland, a co-author on the current paper, who studies the chemical origin of life on Earth.

In a paper published in 2015, Professor Sutherland’s group at the MRC LMB proposed that cyanide, although a deadly poison, was in fact a key ingredient in the primordial soup from which all life on Earth originated.

In this hypothesis, carbon from meteorites that slammed into the young Earth interacted with nitrogen in the atmosphere to form hydrogen cyanide. The hydrogen cyanide rained to the surface, where it interacted with other elements in various ways, powered by the UV light from the sun. The chemicals produced from these interactions generated the building blocks of RNA, the close relative of DNA which most biologists believe was the first molecule of life to carry information.

In the laboratory, Sutherland’s group recreated these chemical reactions under UV lamps, and generated the precursors to lipids, amino acids and nucleotides, all of which are essential components of living cells.

“I came across these earlier experiments, and as an astronomer, my first question is always what kind of light are you using, which as chemists they hadn’t really thought about,” said Rimmer. “I started out measuring the number of photons emitted by their lamps, and then realised that comparing this light to the light of different stars was a straightforward next step.”

The two groups performed a series of laboratory experiments to measure how quickly the building blocks of life can be formed from hydrogen cyanide and hydrogen sulphite ions in water when exposed to UV light. They then performed the same experiment in the absence of light.

“There is chemistry that happens in the dark: it’s slower than the chemistry that happens in the light, but it’s there,” said senior author Professor Didier Queloz, also from the Cavendish Laboratory. “We wanted to see how much light it would take for the light chemistry to win out over the dark chemistry.”

The same experiment run in the dark with the hydrogen cyanide and the hydrogen sulphite resulted in an inert compound which could not be used to form the building blocks of life, while the experiment performed under the lights did result in the necessary building blocks.

The researchers then compared the light chemistry to the dark chemistry against the UV light of different stars. They plotted the amount of UV light available to planets in orbit around these stars to determine where the chemistry could be activated.

They found that stars around the same temperature as our sun emitted enough light for the building blocks of life to have formed on the surfaces of their planets. Cool stars, on the other hand, do not produce enough light for these building blocks to be formed, except if they have frequent powerful solar flares to jolt the chemistry forward step by step. Planets that both receive enough light to activate the chemistry and could have liquid water on their surfaces reside in what the researchers have called the abiogenesis zone.

Among the known exoplanets which reside in the abiogenesis zone are several planets detected by the Kepler telescope, including Kepler 452b, a planet that has been nicknamed Earth’s ‘cousin’, although it is too far away to probe with current technology. Next-generation telescopes, such as NASA’s TESS and James Webb Telescopes, will hopefully be able to identify and potentially characterise many more planets that lie within the abiogenesis zone.

Of course, it is also possible that if there is life on other planets, that it has or will develop in a totally different way than it did on Earth.

“I’m not sure how contingent life is, but given that we only have one example so far, it makes sense to look for places that are most like us,” said Rimmer. “There’s an important distinction between what is necessary and what is sufficient. The building blocks are necessary, but they may not be sufficient: it’s possible you could mix them for billions of years and nothing happens. But you want to at least look at the places where the necessary things exist.”

According to recent estimates, there are as many as 700 million trillion terrestrial planets in the observable universe. “Getting some idea of what fraction have been, or might be, primed for life fascinates me,” said Sutherland. “Of course, being primed for life is not everything and we still don’t know how likely the origin of life is, even given favourable circumstances – if it’s really unlikely then we might be alone, but if not, we may have company.”

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The study: http://advances.sciencemag.org/content/4/8/eaar3302

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81 thoughts on “Scientists identify Earth-like exoplanets

  1. The whole subject of exo-planets is based on extrapolation of “hints and rumors” that are then used to confirm the science fiction version of the Universe that most of today’s astronomers and space physicists grew up on — as did I.
    Those hints and rumors, those periodic changes in brightness of distant stars, are imagined into spinning plants and re-imagined into possible distant civilizations.
    Mankind is still trying to figure out how our home planet works….yet has the hubris to think that it can know something about planets it can not see nor measure.
    We need to get back to knowing when we are fooling ourselves. It is fun to imagine what life out there is like, but let’s not pretend that we have scientific evidence of its existence — we do not.

    • Kip,

      Though I agree with your comment, Professor Sutherland’s last two paragraphs are very realistic in their conclusions and he does not seem to be among those convinced of the science fiction rendition of the universe that many of today’s scientists seem to be. Some new science does result from many of these conjectures as long as we continue to recognize how thin the ice really is and remember to not take these maybes as fact nor report them as such, as many of today’s scientists seem to do.

    • It’s always “Are we alone?” as if being alone is a problem or that 7.2 billion people can’t really be alone. I wonder at the psychological state of those who use this reason for searching.

    • Kip,
      What counts as an observation in your book and what is a “hint and rumors”? Is an electron miscropscope image a “hint and rumor” or a real observation? What about gravitational wave observations? Science is full of measurements of things that cannot be directly observed but that doesn’t mean they aren’t real.

      No-one has every seriously suggested extra-terrestrial life or civilisations or found any evidence for them. The evidence for planets is solid. They have been confirmed by multiple different methods by different teams.

  2. “and as an astronomer, my first question is always what kind of light are you using, which as chemists they hadn’t really thought about,” said Rimmer

    Sheer, absolute unadulterated BS.
    Shot:
    Organic chemists do not know about the connection between wavelength and energy?????
    How stupid does he think we are?
    Chaser:
    One of the first experiments undergraduate Organic Chem. students run is the halogenation of alkanes via UV(!) radiation.
    The UV breaks bonds and drives the reaction.

    This guy is not only an idiot, he is an insulting idiot.

  3. I find it amazing that some people still believe that life started out via chemical reactions. But I digress. If they want to find a possible home for ETs then they need to read and follow the advice in “Rare Earth” and “The Privileged Planet”

    • Eugene Koonin is a recognized expert in the field of evolutionary and computational biology. His 500-page book, The Logic of Chance, provides a comprehensive but quite technical discussion of the chemistry and genetics involved in the development of life. Although it is is mentioned throughout the book, chapter 12 focuses on the origin of life.

      Koonin concludes that the origin of life is so complex that the the only way it could happen is if the cosmological Many Worlds in One (MWO) interpretation is true. If so, it’s extremely unlikely to have occurred more than once in this universe.

      For more on the MWO, see https://en.wikipedia.org/wiki/Many-worlds_interpretation

      • Obviously the many origin of life researchers around the world disagree with Koonin. His view is antiscientific. Science seeks natural explanations for observed phenomena, rather than saying, “It’s just too hard for me to figure out, so it must be due to multiple universes!”

        In fact, great strides have been made in this century in explaining the origin of life. One of the leading researchers, Nobel Laureate Szostak of Harvard might be overly optimistic, but thinks we’re only five to ten years away from creating artificial protocells.

        Now if Koonin said that we happen to exist in one of those rare universes whose physical rules allow hydrogen atoms to form, hence stars and galaxies, thus also heavier atoms such as carbon, nitrogen, oxygen and the other biochemically important elements, then he might be onto something.

        • “His view is antiscientific.”

          Really? Why and how, since Koonin is not suggesting a non-natural explanation?

          “Szostak … thinks we’re only five to ten years away from creating artificial protocells.”

          In the 2006 book, The God Delusion, Richard Dawkins said: “I shall not be surprised if, within the next few years, chemists report that they have successfully midwifed a new origin of life in the laboratory.”

          What Dawkins didn’t say is that such success in the laboratory, aided by the accumulated biological knowledge of over a hundred years and use of incredibly sophisticated tools, would only demonstrate that life could originate through intelligent agency.

          • Ralph,

            It’s antiscientific to shrug your shoulders, toss up your arms and claim that a problem is too hard to solve. It’s scientific to try to discover an explanation. That’s what origin of life researchers are doing.

            Dawkins didn’t say that because that’s not what researchers are doing. I’d urge you to study OoL research. Scientists have succeeded in discovering how the building blocks of life arise spontaneously. That intelligent researchers have found out how all the constituents of life self-assemble doesn’t mean that it takes sentient beings for this to happen. It occurs in space without anybody around.

            The same will apply when protocells are made in the lab. It will be without the need for researchers. All they do is test hypotheses about how to achieve polymerization without biological enzymes. Maybe the way or ways they discover in which this happens might not be how it actually occurred on earth or in space. But at least it will show that no intelligent agency be required, under the right conditions.

            Researchers need to create conditions similar to those which obtained on earth four billion years ago. Nowhere on the surface of our planet or near it do those conditions still exist. There was little or no free O2 gas and the oceans were rich in iron. Continents were small. The atmosphere was probably composed of gases released by volcanoes, ie H2O, CO2, SO2, CO, S2, Cl2, N2, H2, NH3 and CH4. Specialists disagree as to the temperature, but it was hotter than now. And of course, there were no organisms in the late Hadean or early Archean environment, so experimental conditions need to be sterile.

            It seems to me that Dawkins hasn’t kept up on abiogenesis research, or he wouldn’t have made such an optimistic prediction. But in the past decade, important issues have been resolved. I still think that Dr. Szostak is overly optimistic, but he knows a lot more about the problems involved than do I. Other scientists say that a protocell will be created through natural chemical processes in the lifetime of most people alive now.

          • “It’s antiscientific to shrug your shoulders, toss up your arms and claim that a problem is too hard to solve.”

            That’s a straw man, Theo. Koonin did not say that at all. He said the abiogenesis issue was incredibly difficult, but suggested a naturalistic scenario that could overcome those difficulties.

            Or are you suggesting that the Many Worlds in One (MWO) interpretation is antiscientific?

            If you’re going to play the positive thinking game, you should say the Heisenberg uncertainty principle must be even more unscientific. It doesn’t say its problem is too hard to solve; rather that it’s impossible to solve.

            (I apologize for the delayed response. I had to take care of some other things yesterday.)

          • Ralph,

            No worries.

            It’s not a straw man. While it might in fact be true, the Multiverse is presently not a scientific hypothesis, since it can’t make testable predictions capable of being shown false. At best it’s metaphysical. When and if evidence supporting it be found, then it could enter the realm of science.

            OTOH, origin of life researchers disagree with Koonin and are busy doing what he imagines is too difficult to do. That is, try to figure out how life arose on earth or in space from its constituent compounds, ie nucleotides (themselves compounds of sugar, phospate and nucleobases), amino acids and lipids. They, unlike him, are practicing the scientific method.

      • I’ve not read Koonin’s book but (if I understand him correctly) Michael Denton has a similar view that there is an issue with the ability of chance as we currently understand it to create the first living organism.

        Again, if I understand correctly, he appears to support the idea that there is something as yet undiscovered in the make-up of matter that encourages life to develop, somewhat analogous to there being something in the make-up of certain chemicals that causes them to create an organised crystal lattice as they condense.

        I understand the issue with chance (generating even the simplest self-replicating cell from inanimate matter requires multiple simultaneous coincidences, and the odds against this happening expand uncontrollably as the number of coincidences increase); but I am not sure that I like his explanation

        • John Hardy,

          No coincidences required; just chemistry. All the building blocks of life self-assemble under a variety of environments in space and on earth.

          The key unresolved issue is how these constituent complex organic compounds form polymers in the absence of biological enzymes. A number of fruitful hypotheses are being actively investigated.

          • That’s not a good analogy, since we know that abiogenesis did occur, and in general how.

            As I keep repeating, the two main remaining issues are polymerizing nucleotides, and then how to unzip a replicated RNA strand from its template. The latter problem might have been solved by the Szostak lab.

            Again, I repeat. We know that all the building blocks of life self-assemble, and the reaction pathways by which they do. Some are simple. Adenine is produced, for instance, simply by heating HCN, a compound abundant in the universe.

            Other pathways are more difficult, such as those recently discovered by Sutherland. But that these constituents of life form spontaneously isn’t an issue, since we find them in meteorites.

          • “All the building blocks of life self-assemble under a variety of environments in space and on earth.”

            Really, Theo? Are you saying that if you take some cells apart in a test tube they will reassemble themselves into living organisms?

            Could you provide links or references to studies that have empirically demonstrated self-assembly on anything beyond a trivial scale?

      • If he had the science then he would also have a Nobel Prize as that would be the biggest scientific discovery ever.

    • Joe,

      If not through chemical reactions, then how?

      All the key building blocks of life self-assemble, to include lipids, sugars, amino acids and nucleotides. Sutherland’s lab recently figured out how the last two unresolved ribonucleotides do so. As noted below, all these components of life have been found in meteorites, to include far more than just the 22 amino acids used by living things on earth.

      Lipids spontaneously form vesicles in water. Amino acids naturally form oligomers (peptides), and the nucleotides combine to make oligomers of RNA. The trick is getting the peptides to keep bonding into polymers (proteins) and ditto for the short RNA chains into long polymers.

      • Theo, in terms of understanding abiogenesis, it’s going to take more than just chemistry as you keep saying. It may require a deeper understanding of nanotechnology — that boundary between Newtonian physics and quantum mechanics. As you know, the rules governing structure and function across spatial sizes change, and how those rules interface and or change at boundaries is currently not fully understood.

        • With life, we’re not dealing on that scale. Biochemistry is just organic chemistry. Plus some physical chemistry, but abiogenesis doesn’t rely on subatomic reactions (although a hydrogen ion is a proton, so could be considered a subatomic particle, as of course too are electrons). They’re no different from any other chemical reactions. This has been known since the 19th century.

          https://en.wikipedia.org/wiki/Vitalism#19th_century

          Proteins and nucleic acids are macromolecules, not nanostructures.

          • “Australian researchers have experimentally shown that microscopic systems (a nano-machine) may spontaneously become more orderly for short periods of time–a development that would be tantamount to violating the second law of thermodynamics, if it happened in a larger system. Don’t worry, nature still rigorously enforces the venerable second law in macroscopic systems, but engineers will want to keep limits to the second law in mind when designing nanoscale machines. The new experiment also potentially has important ramifications for an understanding of the mechanics of life on the scale of microbes and cells.” https://rsc.anu.edu.au/~gmw/newsonFT.rtf

            Granted, this experiment was done quite some time ago (2002), and I haven’t researched any verification/refutation experiments done by others; but cellular structures and processes do encompass the nanoscale (approx. 1 to 100 nanometers). The “unwound” human DNA strand is approximately 2 nm wide by 1.8 m long. The packaging of its billions of nucleotides into chromosomes varying from 1 μm to 2 μm in length does encompass macro-, nano-, and sub-nano scales.

            Use Google Scholar to list all of the reputable scholarly journals associated with the keywords abiogenesis and nanotechnology.

            An understanding of self-assemblage across these scales is needed. How much of that is currently a part of chemistry, and how much will come from further knowledge about nanotechnology remains to unfold.

          • NOAA,

            My point is that we already know that the essential building blocks of life self-assemble, and the reactions which cause them to form.

            Sorry to repeat, but the remaining hurdle is chemical. How do you keep more ribonucleotides continuing to bond together after the first several, faster than they break apart. The nucleotides are joined by phosphodiester bonds to form the sugar-phosphate group backbone of RNA and DNA.

            Today this reaction is catalyzed by biological enzymes. Researchers are looking for prebiotic enzymes which can keep the nucleotides polymerizing faster than they break apart.

            Maybe quantum computing can help in this search, but so far biochemists have found a number of purely chemical means to keep the chain growing, from minerals to ice to warm-dry cycles in thermal spring pools.

          • Abiogenesis for this Earth may be too strict a constraint for starting from scratch. Extraterrestrial contamination may have been involved. Of course that just defers the question of OoL to some other place in the Universe, so the original question regarding how OoL came about remains. However abiogenesis occurring outside of our planet’s early environment may have had a different environment for its OoL, in which case one should not feel constrained to “keep the chain growing from minerals to ice to warm-dry cycles in thermal spring pools.” –i.e. consider whatever chemical means that would keep the chain growing, and from that, postulate the environment.

      • Some sort of intelligent design. For example take a look at the architecture of ATP synthase: http://www.atpsynthase.info/FAQ.html#Sec4

        If you take a look at ATP synthase you can see it consists of two major subunits (F0 & F1) that are connected together by an external tether. This tether doesn’t have anything to do with the functionality of either subunit but without it no ATP synthase. The problem for evolution by blind and mindless processes is exacerbated. Not only does it need to produce the two subunits but one has to be embedded in some membrane so that a gradient can be formed. And the other has to to be stably tethered to the membrane the proper distance away. The tether looks like the membrane subunit F0 somehow formed an external docking site the proper length with F1 forming an external mating site.

        Again these two different protein subunits, the tether and mate, have nothing to do with the function of the protein complexes they are attached to and tether together. And without them there is no way to get the two working subunits together to produce ATP.

        There you have it- A simple external tether that stably holds the major F1 subunit/ rotary motor the proper distance away from its F0 motor force is evidence for the Intelligent Design of ATP synthase. The two major subunits and how it works is just icing on the cake.

        • Joe,

          Intelligent design is an antiscientific religious doctrine, for which no evidence exists because none could. Whenever its acolytes try to make testable predictions, they are always shown false. There is no such thing as irreducible complexity.

          How ATP synthase forms is no mystery. It’s understood in detail. As you know, ATP is the energy currency of cells, so its synthesis has been studied thoroughly.

          The enzyme’s synthesis from adenosine diphosphate (ADP) and inorganic phosphate (Pi) requires energy, as it would normally proceed in the reverse direction. In order to drive this reaction forward, ATP synthase couples ATP synthesis during cellular respiration to an electrochemical gradient created by the difference in proton (H+) concentration across the mitochondrial membrane in eukaryotes, or the plasma membrane in bacteria.

          How it works in archaea, the third domain of life, was elucidated in 2014:

          ATP synthases from archaea: The beauty of a molecular motor

          https://www.sciencedirect.com/science/article/pii/S0005272814000917

          There is no evidence whatsoever supporting the antiscientific, theological doctrine of ID, and all the evidence in the world against it.

  4. OMG – How Profound.

    “if it’s really unlikely then we might be alone, but if not, we may have company.”

    If we are not alone, we might have company!!!

  5. Right. They have been looking at Pluto for how long? They couldn’t see. But we sent a spacecraft and discovered all sorts of interesting things, like an atmosphere, mountain ranges of water-ice mountains, internal planetary heat, water-ice seas? So why couldn’t they see all that “stuff”. When they looked at Pluto through their very sophisticated telescopes they could only see what they expected to see.

    Or the astronomers’ obsession with canals on Mars – they worked for decades collectively, “mapping” the canals, until Mariner flew by in 1965. Never mind.

    I don’t believe they have enough information, i.e. evidence, to draw the conclusions they are drawing about what they have discovered. They think it would be really cool to discover earth-like exoplanets and “presto” they found them.

  6. “lie within the habitable range where liquid water can exist on the planet’s surface.” Given life exists on earth thousands of feet down around volcanic vents, based on a hotwater/sulphur biology, and not sunlight, this restriction is invalid.

    • Yeah, but sunlight or no, all life on Earth depends on liquid H2O. It’s very reasonable to use that as a first-tier condition in the search for exo-life.

      • Why might life not develop based on say ammonia?

        Why do we always have to think of our planet as a model for life.

        • Some have supposed that life as we don’t know it might have developed in the ethane lakes of Titan.

  7. The paper implies that the deep problem of abiogenesis is now resolved and is achieved by an UV driven mechanism. Is it so? I haven’t yet had the stunning news of earthly abiogenesis resolution.

    • Sutherland recently succeeded in showing how the last two ribonucleotides are spontaneously synthesized. Other scientists had previously found the self-assembly pathways for the other two.

      This is good to know, but we already knew that all deoxyribonucleotides and ribonucleotides self-assemble, since they have been found in meteorites from asteroids. Presumably the same processes occur in space as on earth.

      RNA autosynthesizes in a variety of environments, but only in short chains (oligomers of nucleotides) rather than long polymers. So the remaining key discovery in OoL research is figuring out how to form polymers in the absence of the protein enzymes which catalyze this bonding reaction today.

      We also have to learn how to separate strands of RNA after they’ve replicated, as well. Much progress has been made on various fronts to solve these chemical engineering challenges.

      Here’s but one instance of a large and growing literature on the topic:

      https://onlinelibrary.wiley.com/doi/full/10.1002/chem.201503906

      Please see citations.

  8. I would suggest we focus our efforts figuring out the precise chemical steps to the development of life as it has developed here on Earth. Only then can we reasonably look elsewhere for similar conditions. Absent that it’s just guessing and should be recognized as such.

    • Considering DNA as both hardware and software for replicating life, our efforts to figure out the precise chemical steps to develop life as it has developed here on Earth will not be trivial. I can imagine the headlines now: “Modelers Using Quantum Computers have Developed Life”

        • Research in biochemistry has now begun to rely heavily on computer modeling of complex biochemical reactions and metabolic pathways. Unless you are willing to experiment around for millions of years as done naturally on Earth, the chemical creation of life will not be carried out in glassware until those natural steps are explicitly determined using quantum computers.

          • There might be some OoL researchers using quantum computers, but all those I know just conduct chemistry experiments.

            Discovering the origin of life, or a possible one, as I’ve noted, requires solving the polymerization problem. To do so, hypotheses must be tested experimentally. Other issues have been explained by often quite simple experiments.

            I’m not quite sure how quantum computers could help, really.

            Where we are now is that we have self-assembled oligomers of RNA. ie chains of a few to several nucleotides. We need to keep those oligomers from splitting apart, so that they continue to grow longer, without using biological enzymes.

            It’s just a chemical engineering problem. Various avenues are being profitably pursued.

  9. Carbon is a necessary requirement for Carbon Based Life Forms. As we know, atmospheric Carbon Dioxide is integral to the Carbon Cycle of life, in other words, the Carbon Cycle cannot complete without CO2.

    From this we might conclude that only planets that have sufficient atmospheric CO2 would be able to support life. Now let’s consider three sister planets:

    Venus –> 95% CO2 atmosphere
    Earth –> 0.04% CO2 Atmosphere
    Mars –> 95% CO2 Atmosphere

    Wouldn’t we discount Earth and look more closely at Venus and Mars in an attempt to find life?

    • No we would see the water signature and go from there. But that assumes there are older civilizations then Earth and there is no evidence (so far) that there are. So following the data, we are the oldest civilization int he galaxy until such time that there is data to disprove that.

  10. If you believe in evolution, then all living creatures evolved from one original First Organism. All other creatures came after this First One.

    Logically, it would seem that the most benign environment available would be the most likely place for life to begin. Harsh environments like around “black smokers” in the deep ocean would be less likely to be a place where life would develop. Instead, life would develop in a benign environment, and then migrate to harsher environments and adapt to them.

    I do wish the astronomers would stop saying Super Earths are “Earth-like”. Imo, it’s not Earth-like if the surface gravity is two or three or more times the gravity of the Earth.

    I also wish that astronomers would stop referring to objects in space as if they are living, thinking beings. I know they won’t stop talking about stars and galaxies as though they were human, with human traits, but it’s really kind of irritating to me since I know that none of those stars or galaxies are alive. A nitpik, I suppose.

    There probably won’t be much of a space program for a civilization that lives on a Super Earth. We have enough trouble getting into space from here and we are only fighting one gravity.

    • “If you believe in evolution, then all living creatures evolved from one original First Organism. All other creatures came after this First One.”

      That is a bold assumption. There is no reason not to suspect that life could have began with several different organisms in several different places.

      I think one of the main conditions, along with water, for development of life is having a moon that would create tides. These tides help expose early life forms to UV as they get deposited on land. UV would be the catalyst for mutation and evolution.

      • Tom,

        Both bacteria and archaea use the same replication system, but have different membranes. Hence it’s possible that they descend from RNA-containing protocells which evolved different membrane structures and independently adopted double-helical DNA as the information storage molecule, thanks to its greater stability, which owes to its ribose (five carbon) sugar’s missing an oxygen atom.

        The nice thing about RNA is that, since it’s single-stranded, it can form complex shapes by bending in upon itself, thus enabling it to act as an enzyme, ie ribozyme.

    • The most benign environment imaginable would be one which is completely stable. ie. No reactive substances whatsoever. How would this result in any reactions to advance naturally occurring molecules to assemble? For that matter, how would this result in the creation of those molecules from constituent atoms?
      Your hypothesis flounders on this fact alone.

      • John,

        Some origin of life researchers still argue for organisms first arising around deep sea hydrothermal vents, but increasingly they are drawn to Darwin’s conjectured “warm little ponds” on land. In volcanic areas, like Yellowstone today, on the limited continents of four billion years ago, thermal pools with wet and dry cycles promote polymerization of nucleotides into long RNA chains.

        Life flourishes in hostile environments today, but might have originated under more “benign” conditions.

      • Actually John, I said “the most benign environment available”. Naturally there would have to be some outside stimulation such as UV radiation to get things moving.

        I was speculating that life would have a better opportunity to develop on the Earth’s surface as opposed to developing in the ocean around a black smoker, although I probably didn’t do a good job of explaining myself. That’s not to say that life might be able to develop in all sorts of environments, but it seems to me that some places are better than others.

    • Tom,

      Evolution isn’t a matter of belief any more than is gravity. It’s a scientific fact, that is, an observation of nature. Both evolution and gravity have bodies of theory seeking to explain how they work.

      However, evolution deals with the origin of new species, genera, families, orders, classes, phyla, kingdoms and domains of living things, not of life itself. That’s called abiogenesis.

      • “Evolution isn’t a matter of belief any more than is gravity. It’s a scientific fact, that is, an observation of nature.”

        I’m not arguing against evolution. It’s looks like a viable theory to me. Although there are a lot of unanwered questions about it.

        • Evolution is a fact, ie an observation, as well as a theory. Same as gravity and theories of gravitation. Evolution is however better understood than is gravitation.

    • It appears that life develops in environments where there is plenty of readily available energy. That’s why we find life around the “black smokers”. For the organisms that live there, that’s perfectly benign. What else MUST be present for Life? I’m not sure that even the best researchers have figured out all of it. It may not even require carbon.

      • Carbon is ideal, as the lightest and most common element in Group 4 of the Periodic Table, ie atoms with valence of four. For the same reason, nitrogen (Group 5) and oxygen (Group 6) are also well suited for biochemistry. Fluorine (Group 7) is too reactive and much less common.

        I suppose that Si (Group 4), P and S might also work, despite being heavier and generally less common in the solar system (and probably about the same for our galaxy). Si-28 is the seventh most common nuclide, after H-1, He-4, O-16, C-12, N-14 and Ne-20.

        P and to a lesser extent S are important biochemical elements. S-32 is the #10 nuclide in the SS. P is rare overall, but more abundant in earth’s crust, happily, since it’s essential for RNA, DNA and such vital biomolecules as ATP, ADP, AMP and phospholipids.

        Organic (carbon) compounds, such as PAHs (polycyclic aromatic hydrocarbons), abound in the universe. They form readily under a raft of conditions. PAHs can catalyze the synthesis of RNA.

  11. Exoplanets are a lot like computer models predicting the future based on incorrect or incomplete assumption and little or bad data. No one alive today will be around to validate either. My problem is that we the USA being trillions in debt and still deficit spending why are the taxpayers on the hook for such research.

      • Theo, so it took until 2014 to get a “good” image of an exoplanet using, I would imagine, a computer model to analysis a specific spectrum of light to produce the image. Even if it is it is a reliable image, it still doesn’t come close to figuring out what the atmosphere/ climate, with any detail, for that or any exoplanet might be. It is just like using computer models to guess what our climate might be a hundred years from now. We are still debating the presences of water on Mars , the present of which was not discovered until 2012 and it is a whole lot closer than the nearest exoplanet. The closet exoplanet is a around 4 light years away. Unless we develop travel at the speed of light then my statement still stands, no one alive today will be able to confirm what the atmosphere might be or actually was. Go back and read the link you sent. Think about the relative size and distances involved.

        • We can discover the composition of exoplanet atmospheres by analyzing the spectra of their constituent gases.

          • From 4.2 to 12 light years away through our atmosphere and any intervening gases along the way??? Ok, if you say so. My original statement still stands. No one alive today will ever be able to confirm or deny either the hypothetical atmosphere of any exoplanet or the results of climate models. Both are a bridge too far.

      • For either, what would be the energy source? Real energy like heat or light, not just potential energy such as a hydrocarbon. We’re never going to find life on Mars, and probably not on Titan unless there is a molten core to supply geothermal energy. At that distance from the Sun that light energy is too diffuse, too weak, to kickstart any Life.

        • Red,

          For the moons of Jupiter and Saturn, energy sources include tidal gravitational forces and intense radiation. Enceladus, Europa and probably other moons have oceans of liquid water under their icy shells thanks to rocky core heating from the gas giant planets’ powerful gravitation.

  12. And the planets are how many light years away? A lot could happen to a planet in just one light year let alone 1000 light years or more.

    • And the planets are how many light years away? A lot could happen to a planet in just one light year let alone 1000 light years or more.

      Careful about your assumptions about distance there!
      Sure theoretically, a planet “only” one light year away “could be” only one year away (for communication) – but getting there requires both a long acceleration period, a turn-around, and then an equally long deceleration run, plus many more (potential) weeks or months of near-planet maneuvering to get to an entry position. All depends on how the traveler is accelerated and with what mass.

      It would be interesting to see an app or web-site with the basics of the calculation: passenger mass of all consumables and needs, rocket structural mass, ejected mass through some assumed method of known physics, max acceleration, distance, etc. for any theoretical extra-solar trip. At what point are you needing an asteroid-sized “rocket” to get enough reaction mass to make the journey up to speed and then slow back down at a liveable traveling acceleration?

    • ∈ Eri is 10.5 light-years from us. I suppose that’s one of the reasons it was part of the study and probably why they think they can identify a planetary system there.

      Proxima Centauri and Gliese 832 are closer and AD Leonis is farther, as I recall. Those are all M class.

  13. there are as many as 700 million trillion terrestrial planets

    And the nearest of them is at least 40,000 years away with current technology (like Voyager 1).

  14. Chemists were trying ultraviolet light in origin-of-life experiments back in the 1970s, and of course Miller’s famous experiment with high-voltage electric sparks necessarily involved a fair bit of UV. It is not clear to me what is new here.

    I find the ongoing search for extraterrestrial planets awesome and amazing, but I am heartily sick of people writing about “Earth=like” planets when they are only roughly similar in size and little or nothing is known of their chemistry.

    • What is new is that astronomers are looking at planets around stars which produce the specific UV wavelengths which Sutherland showed make the last two nucleotides whose spontaneous synthesis hadn’t yet been worked out.

      We already knew that all the building blocks of life self-assemble, but Sutherland recently showed specifically how two important ones do so.

      The astronomers ran with that discovery to add another restraint on the concept of the habitable or abiogenetic zone.

      Miller’s experiment merely produced a random sludge of amino acids.

      Of course life as we don’t know it could be energized by different EM radiation.

  15. Biogenic C isotope ratios in 4.1 billion year old carbon in Zircon :
    http://www.pnas.org/cgi/doi/10.1073/pnas.1517557112
    This is the second such report.

    Looks like life is there from the beginning , a universal principal. It likes to express asymmetry, chirality.
    Living machines, which we cannot make (yet) are simply jaw dropping – take the chloroplast efficiency :
    https://physicsworld.com/a/is-photosynthesis-quantum-ish/
    (Beautiful discussion of quantum machines)

    The entire “abiogenesis” meme harks back to Newton’s essences from stone – see the last alchemist’s writings. This “spontaneous” emergent stuff, also found in von Hayek’s economics, is pure magic.

    We know some of the trademarks of life, from Pasteur, Redi, Vernadsky. I do not know if the ALMA telescope could measure polarization in proto-planet clouds where organic – like molecules have been identified. As far as I know no Martian lander has checked for chirality.

  16. Chemical environment is only a part of the picture. Stability (conferred on Earth by our massive Moon) and a world ocean within the pH range tolerated by life are equally important.

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