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The Panspermia Paradox

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Seed dispersal in the galactic garden? (Image adapted from A. Valavanis)

The notion of panspermia – the transferral of viable organisms between planets, and even between star systems, seems to be getting a bit more attention these days. One only has to open this previous week’s copy of TIME magazine and there it is, via a very nice piece by Jeffrey Kluger on ‘Aliens Among Us‘.

There is no doubt that planetary surface material is continually being shipped around between rocky planets and moons in our solar system. Ejected by high energy asteroid or comet impacts, chunks of stuff follow a range of orbital trajectories that result in both eventual return to their origins or transferral to the surfaces of other worlds. Increasing evidence suggests that a variety of (typically microbial) organisms could be carried along, surviving both the extremes of pressure and acceleration, as well as exposure to thousands to millions of years of interplanetary space. They need not do this in stasis, tucked well inside the interstices of rock and ice it’s not inconceivable that microbes could be passengers in the natural equivalent of the generation ships of science fiction.

It means that there is a real possibility for life to both cross-infect, and even to be ‘seeded’ from planet or moon to planet or moon. And I’ve written about this before, in the context of life on Mars (see ‘We Are the Aliens‘).

Enthusiasts for panspermia go further, and have been known to invoke these mechanisms for galaxy-wide dispersal of life – taking one rare occurrence of life and spreading it across the stars. In some ways the motivation for proposing this kind of cosmic panspermia is a little dated. It comes from a time when we felt that the origin of life of on Earth was such a mystery, and such an unlikely event, that it was convenient to outsource it. Although this didn’t actually solve the real question of life’s origins, it meant that a specific origin ‘event’ could be extremely rare among the 200 billion stars of the Milky Way yet life would still show up in other places.

These days I think our discoveries about the remarkable abundance and diversity of so-called pre-biotic chemistry (the stuff that represents all the underlying building blocks of bio-chemistry) in every nook and cranny of our solar system, and even in the proto-stellar nebula of other stars and the wilds of interstellar space – swings the pendulum back to Earth. Nature seems very adept at making all the pieces for life, apparently raising the odds of local bio-genesis.

But this doesn’t mean that interstellar, galactic panspermia isn’t still relevant. It might be happening. And this gets me to the paradox of the title. There is a factor about large-scale panspermia that to my knowledge is rarely considered, and that is natural selection. You and I, or fluffy bunnies and daffodils are all unlikely candidates for interplanetary or interstellar transferral. The sequence of events involved in panspermia will weed out all but the toughest or most serendipitously suited organisms. So, let’s suppose that galactic panspermia has really been going on for the past ten billion years or so – what do we end up with?

Small, tough, and capable of interstellar travel?

Although it involves a complex web of factors, it seems likely that life driven by cosmic dispersal will probably end up being completely dominated by the super-hardy, spore-forming, radiation resistant, chemical-eating, and long-lived but prolific type of critters. There may be no advantage to a particularly diverse gene pool. Billions of years of galactic transferral will have whittled it down to only the most indelicate and non-fussy microbes – super efficient, super persistent, and ubiquitous – the galactic top dogs.

Now, we might argue that there are organisms on Earth that could fit the bill, and could represent the most direct descendents of these ancient interlopers. Slow-living, low-metabolism chemoautotrophs abound, and our knowledge about these proverbial bottom-feeders is still very limited.

But the problem, and the potential paradox, is that if evolved galactic panspermia is real it’ll be capable of living  just about everywhere. There should be stuff on the Moon, Mars, Europa, Ganymede, Titan, Enceladus, even minor planets and cometary nuclei. Every icy nook and cranny in our solar system should be a veritable paradise for these ultra-tough lifeforms, honed by natural selection to make the most of appalling conditions. So if galactic panspermia exists why haven’t we noticed it yet?

There are all sorts of plausible reasons. The simplest is that we’ve not yet managed to look very hard in all these places. It’s also possible that we’ve just not put two and two together while studying the properties of terrestrial extremophilic organisms. But suppose we keep looking hard and find nothing – this would argue strongly against the possibility of galactic panspermia at all. And this would be interesting, because it would also serve to place a limit to the true extremes of life, a physical and chemical boundary condition. Perhaps the root cause turns out to be gravitational dynamics (interstellar transfer may be horrendously inefficient), or just the environmental limits of bio-chemistry and the molecular machines at the core of it all. In either case a null result might actually tell us something vitally important about the phenomena of life, and our own cosmic significance.

[This post has been adapted and expanded from a post in the Life, Unbounded archives]

Caleb A. Scharf About the Author: Caleb Scharf is the director of Columbia University's multidisciplinary Astrobiology Center. He has worked in the fields of observational cosmology, X-ray astronomy, and more recently exoplanetary science. His latest book is 'Gravity's Engines: How Bubble-Blowing Black Holes Rule Galaxies, Stars, and Life in the Cosmos', and he is working on 'The Copernicus Complex' (both from Scientific American / Farrar, Straus and Giroux.) Follow on Twitter @caleb_scharf.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. brigklyce 12:41 pm 10/15/2012

    Dear Dr. Scharf — You wrote, “…if evolved galactic panspermia is real it’ll be capable of living just about everywhere.” As we know, life is capable of _surviving_ just about everywhere that is not hot enough to sterilize it. And evolution makes its changes only when life has become established, not when metabolism and reproduction are turned off, as for space travel. Therefore life might actually be everywhere, but only flourish in the “right” kinds of environments. These would need liquid water, plus materials and energy that are widely available. After seeding, a moon or planet would then need to successfully proceed through long difficult Gaian stages to reach relative maturity such as we have on Earth. Similarly, many seeds may be sown, but only a few trees grow. I don’t see the paradox.

    As for evidence, there’s plenty. One good example is the fossilized germs in carbonaceous meteorites shown at, and links from there. I would enjoy an in-person discussion, if you would. Best regards, Brig

    Link to this
  2. 2. dwbd 1:03 pm 10/15/2012

    This is really another version of Fermi’s Paradox, that is why haven’t Alien Civilizations been through here long ago, if not colonizing all planets, at least leaving artifacts. The Paradox is even more difficult when you consider Panspermia, a good discussion of it here:

    Surely, alien organisms would find there way to other worlds. Some argue that the vast interstellar distances preclude space faring civilizations. But we know it is certainly possible to image distant world’s, determine if they are suitable for life, i.e. mild temperatures and liquid oceans. Then some alien civilizations could send “life bombs” to those worlds and seed them with their own version of life, basically creating World’s ready to be colonized at some point in their future.

    It all makes me think that we may live in a simulated universe, which only has the computational resources to model the development of a complex living world on just one or a few planets. Extra-Solar planets may only be generated as we develop the skills to image them, and only in the detail we our capable of observing. Nick Bostrom on ARE YOU LIVING IN A COMPUTER SIMULATION?:

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  3. 3. Caleb A. Scharf in reply to Caleb A. Scharf 2:39 pm 10/15/2012

    Brig, good points. Here’s my reasoning. I’m saying that the *mechanisms* of panspermia provide the environmental stress that leads to natural selection and evolution of the organisms. So there are a number of factors that we can imagine play a role in an organism’s ‘success’. Yes, they need to be highly resilient to ejection events, capable of long-term ‘stasis’ or able to carry on in very low resource situations during transit. But over very long timescales (i.e. the billions of years I mention) there are other factors that come into play, these include the ability to ‘bloom’ on as many planetary environments as possible, because this increases the likelihood of being transferred on during ejection events (for example). So it’s not just survival, it’s the ability to present a big target for the physical mechanisms of dispersal as well – and that means growing well everywhere. So I don’t think you can sow many seeds if those seeds aren’t produced in copious numbers in the first place!

    I’d disagree that there’s any good evidence in meteoritic material at the moment – all such claims are highly controversial.

    Link to this
  4. 4. jtdwyer 2:47 pm 10/15/2012

    I think the principle issue with the idea that panspermia has an evolutionary impact on existing life on Earth is that anything arriving from elsewhere would have to have some means of interacting the genetic encoded processes that dominate life on Earth. It seems highly unlikely that anything more complex than a virus could have survived the trip in sufficient volumes to have had significant impact.

    However, as I understand viruses are both resilient and opportunistic, so if some viruses did develop somewhere and somehow find their way here they might could have had some genetic influence on the more complex life forms that almost surely developed independently here on Earth.

    It has been suggested I think that complex life forms originally developed from virus-like organisms that could independently reproduce. It would seem that in that case, for some period of time early in the development of life on Earth simple forms of life from elsewhere might could have had significant influence on Earth’s life…

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  5. 5. Torbjörn Larsson, OM 4:58 pm 10/15/2012

    A well argued article, but any short analysis has its gaps. So in the old blog tradition, lets jump onto them:

    - Even between two nearby habitable planets (say, a young Mars and Earth) the likelihood for transpermia is minute. I once did back-of-the-envelope for Mars (no sterilizing Earth-Moon impactor) to Earth and with today’s published observations it is beaten by the hydrothermal vent hypothesis maximum time to life. The mass under transport is too small and nonviable to likely spawn life before it arises locally. [I'm sure I can find it again, if asked.]

    - The idea of non-stasis is intriguing but unrealistic. Most impact ejected bodies would soon deep freeze I take it. Deep freeze spores would eventually be made nonviable by radiation and other aging, IIRC it takes ~ 500 million years but that would be enough with low transfer rates.

    The series of impact event that would launch a deep seeded sizable body quickly diminishes transfer and viability rates to oblivion.

    We end up with a situation where bodies that can sustain a local biosphere evolves it naturally and sterile bodies remain sterile. (But of course possibly retaining a record of unsuccessful transpermia that we should look for.)

    To touch another commenter here, transpermia is not a Fermi situation. The latter is characterized by too loose constraints to be predictable. (For example, one can easily find pathways where cosmic colonization waves are radio et cetera silent.) Transpermia on the other hand seems to be characterized by too rigorous constraints, at least for now.

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  6. 6. Caleb A. Scharf in reply to Caleb A. Scharf 5:17 pm 10/15/2012

    ..and I don’t necessarily disagree with any of these points (although I don’t think we actually have data to prove/disprove any of them at the moment). I think though you perhaps misunderstood the main thrust of my post – I’m actually making an argument that *if* interstellar panspermia happens it should be readily detectable. But that means if no evidence is found it can be ruled out to a high degree of confidence.

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  7. 7. dwbd 5:54 pm 10/15/2012

    @ Torbjörn, actually ejecta from Mars impacts would make it to Earth quite quickly, within a million years, and certainly some bacteria would be viable. It has been accepted that some types of bacteria will survive the space journey for some millions of years.

    And indeed this is all about Fermi’s Paradox. Here is an article where the author argues that we have an obligation for Directed Panspermia:

    With 100′s of billions of World’s in our own Galaxy and billions of years of history, the overwhelming probability is some alien civilizations should have undertaken AT THE VERY LEAST Directed Panspermia, if not galactic colonization.

    And you don’t know what Fermi’s Paradox is all about, it is not just about why we are not finding the odd alien civilization, it is how exponential numbers of growth should result in TOTAL HABITATION of the entire Galaxy by an Alien Civilization, within certainly a few hundred million years. And our Galaxy is about 13 billion years old. It is a VERY DIFFICULT paradox to refute, and NOBODY has ever successfully done so. And the discovery that planets in our
    Galaxy are ubiquitous makes it even harder to dispute.

    Link to this
  8. 8. Anonymous 6:10 pm 10/15/2012

    Life as we know it is fussy because local conditions select for fussy life.

    As for being undiscovered by extraterrestrial intelligences, keep in mind that we have to compete with other life, and apparently we’re just not that interesting.

    Link to this
  9. 9. brigklyce 6:19 pm 10/15/2012

    Caleb, thanks for your thoughtful comments. I am aware that the evidence for fossilized germs in carbonaceous meteorites has not been generally accepted. But when I interviewed several distinguished non-accepting scientist, each agreed that the evidence in his own area of expertise (biology, or chemistry) was unimpeachable. May I encourage you to look at the link (in comment 1) for yourself? May I call on you when I’m in town?

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  10. 10. N49th 7:01 pm 10/15/2012

    Boy, is this in over my head. But here I go.
    Panspermia (translation: life travels between planets).
    Paradox enters the discussion.
    Before we get there, did the author and theorist like writing with a furnace in the basement when the weather was cold. And with an air conditioner when the weather was hot?
    Interesting discussion but I have shale rock all around me with people ready to dig. Maybe not with the best interest of the community around them.

    Link to this
  11. 11. Actually 1:15 am 10/16/2012

    Interstellar panspermia via genetic material is pretty unlikely–just look at the recent Nature paper: even DNA, the tougher of the two major nucleic acids, only has a half-life of about 500 years. The immense radiation of interstellar space (look at the recent Voyager radiation levels) would likely destroy any sort of linear evolving information storage molecule.

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  12. 12. neilrued 3:53 am 10/16/2012

    I agree with Anonymous’ remarks.

    Tough micro-organisms able to survive almost anywhere, may as they reproduced on Earth, have lost some survival abilities because they didn’t require these to live in Earth’s environments. Much in the same way as modern humans, possess vestigial canine teeth, an appendix that used to be a second stomach and now serves to balance intestinal bacterial species, and vestigial third eyelids. To extend this idea further, modern humans living in civilized society, do not extensively use muscles for chasing and hunting prey. We have lost the ability to hunt in groups, and know very little about plants. Consequently, if we are lost in a rain forest on Earth, we’d starve to death, die of intestinal parasites or predatory animals, or dehydrate quickly. Native people, on the other hand, would see an abundance of food, shelter, potable water and medicine.

    Evolution may adapt micro-organisms to degrade certain abilities, for efficiently directing resources to support survival abilities where and when they are required.

    I also agree that our planet may be boring compared with other planets. For the most part, our civilization is composed of corporate entities that encourage employees to climb, claw or push each other out of the way to make a quick buck/yen/yuan/euro. Our geology is mediocre, compare Mauna Kea or Mt. Everest with Olympus Mons, or the Grand Canyon with the Mariner Valley.

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  13. 13. neilrued 4:27 am 10/16/2012

    Edit: On my previous post, the end of the third paragraph should have read as: ….to support relevant survival abilities where and when they are required.

    If Panspermia has been really going on for billions or at least hundreds of millions of years, then this may imply that there would be no such thing as truly alien life forms because if aliens existed, then they would have the same basic DNA as all life on Earth does.

    dwbd’s link to the paper promoting SOLIS’ idea that the human race should devote resources to spreading earth based micro-organisms to other star systems, may be a waste of time and resources, if the point in my previous paragraph is true; there may already exist life that is similar to earth life on earth-like exoplanets. Another point, if there are exoplanet life forms with similar DNA to earth based life, there is no gurantee their micro-organisms may be compatible with Earth life forms.

    On the other hand, if there are no earth compatible life forms on earth-like exoplanets, how can we be guaranteed any particular exoplanet is truly devoid of native life forms? What if we make a mistake and in some remote and secluded region of a selected exoplanet, the first sparks of unique alien DNA are coming together, and we send what would then become a biological warfare attack, with the terrestrial microbes ravenously devouring into extinction the alien DNA?

    Whether the life forms on an exoplanet are based on truly alien DNA or not, we need to be very careful before we embark on any Panspermia project.

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  14. 14. neilrued 4:46 am 10/16/2012

    What do we do with exoplanets that already have life forms on them?

    My opinion, is that we do not directly interact with these worlds. We should leave them alone, to evolve naturally.

    What do we do with planets that are SEEMINGLY lifeless? We should proceed with extreme caution, to make sure there are no life forms that may be very different from us. The greatest tragedy, and the worst crime would be to wipe out whole species because at first we didn’t recognize them as true life forms.

    I agree that exploring for the sake of Science involves risks, but I don’t agree that we should indiscriminately impose risks on others. If we are exploring for improving our Scientific knowledge, we should incur all of the risks.

    Link to this
  15. 15. bongobimbo 9:04 am 10/16/2012

    The real paradox of panspermia is that it assumes earth life originated elsewhere, but then. . . where did life on that planet originate? And so on, backward. It’s the same paradox as the one envisioning a creator god. If a god created the universe, who or what created that god?

    However, as the article points out, the elements for life are abundant, so perhaps continual generation of life on separate planets, with occasional additions from space, might make more sense. Leaving other (lifeless?) planets to develop their own life systems would be the ethical choice, but I’m afraid that tinkering, greedy monkeys like ourselves would insist on going there and metastizing until we exploit & ruin yet another planet.

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  16. 16. RichardHoover 7:49 pm 10/16/2012


    You said that you disagree that there is any evidence for microfossils in carbonaceous meteorites because “all such claims are highly controverisial.” That is not science. I have not made “claims”, I have provided solid evidence–recognizable remains of fossilized filamentous Cyanobacteria that can be associated with known genera and species of these organisms. EDAX data show that these filaments contain nitrogen below the detector sensitivity (below 0.5 per cent atomic) and therefore they can not possibly be modern bio contaminants. I challenge you to address these points scientifically. If you have not seen these images and EDAX data I will be happy to send you some. I have spent almost half a century in the study of micro algae. Diatoms and many genera and species of Cyanobacteria are routinely identified in living and fossil state solely on morphological and morphometric characteristics. Large numbers of well preserved Fossils of Cyanobacteria have been found by me and several other independent paleontologists in freshly fractured interior surfaces of CI1and CM2 meteorites.
    Please address these points with a solid scientific argument as to why you chose to arbitrarily dismiss these images and EDAX elemental analysis data. Just saying these results are “controversial” is hardly a scientific rationale.

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  17. 17. dwbd 8:59 pm 10/16/2012

    neilrued, it don’t matter what you or some particular ethic of the year says about directed panspermia. Our Galaxy is 13 billion years old with 100′s of billions of planets. Even one civilization will maybe for some period of time advocate non-intervention in other worlds, but for some period of time be bold and expansionist as has happened many periods in our own history. It would be inevitable that long ago, many times alien civilizations would have caused at the very minimum total panspermia over the entire galaxy, and alien life bombs would be ubiquitous. The fact that hasn’t happened is startling. Even more surprising is the lack of self-replicating robotic organisms that would quickly (i.e. over millions of years) spread throughout the entire galaxy.

    There is something strange going on here. Believe it.

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  18. 18. brigklyce 9:02 pm 10/16/2012

    Dear Caleb — as a followup to Dr. Hoover’s comments, may I recommend his JOC paper of March, 2011, which is available as a 41-page, 3.9Mb PDF at
    (and possibly elsewhere. Other evidence is also linked from the URL I provided in comment 1.) After reviewing the evidence, you are qualified and welcome to state your objections. Without looking, you are, to be blunt, uninformed. Thanks for your interest, I hope.

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  19. 19. Caleb A. Scharf in reply to Caleb A. Scharf 9:24 pm 10/16/2012


    I certainly didn’t mean to dismiss or disparage your work or that of others, in the spirit of a brief comment in this blog I was trying to point out that (and I think this is fair to say) there is no majority of the community who are convinced of (for example) indigenous microfossils in meteoritic material. Language is tricky in short blogs and in commentary. So, to try to be more precise – I disagree that there is generally accepted positive evidence for microfossils, I don’t disagree that you have evidence that you have presented and worked with and that you feel is a very positive detection. I am not an expert in microscopy or in the details of verification of the structures seen in these samples so I don’t feel I can address the results in any thorough scientific way, but I do think I can express my reaction that as far as I can see based on the community’s response the evidence is not ‘good’ in as much as it hasn’t convinced more than a few people. Is that fair? No, I guess not, and I am entirely sympathetic to the feeling that sometimes science is overly conservative – but this is what I have to go with based on my personal limitations of expertise.

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  20. 20. Caleb A. Scharf in reply to Caleb A. Scharf 9:35 pm 10/16/2012

    Brig. I did read the JOC paper back in 2011 when it came out.

    Link to this
  21. 21. brigklyce 10:10 am 10/17/2012

    Caleb, thanks for telling me you have read the article. What’s frustrating is that no one will engage in a thorough, straightforward examination of the evidence (microfossils in carbonaceous meteorites); they all seem to want it to just go away. I am surprised if you aren’t fairly qualified to judge the issues (contamination?, nonbiological artifacts?) for yourself.

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  22. 22. Combinator 11:25 am 10/17/2012

    Very interesting discussion on the topic which I am thinking about already many years!
    I believe that really some arguments exist that life was probably transformed to Earth (and possibly Mars) from another star system. We can discuss some of them if anybody interested but for beginning can anyone answer to me on the very simple question – why in Murchison meteorite carbon in L-alanine amino-acid “lighter” than D-alanine but for isovaline situation is reverse (see tables 2 and 3 in the paper “The Nature and Distribution of the Organic Material in Carbonaceous Chondrites and Interplanetary Dust Particles”: . I am personally was able find only one logical explanation – because live cells preferably use L-alanine and D-isovaline (which is one of amino acids used in the nonribosomal peptides). Any other ideas?

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  23. 23. neilrued 8:53 pm 10/17/2012

    dwbd,I don’t consider myself to be a particular ethic of the year, I have always subscribed to the philosophy of not interfering with an alien planet’s natural evolutionary process. My motivations are based on the mess the human race has made of the Earth’s environment, and the negative impact European civilization has had on “civilizing” other cultures.

    Perhaps the reason why we haven’t detected evidence for directed Panspermia, is that alien civilizations may simply have advanced to the point where they have found ways to prevent the greedy and violent members of their species from ascending into roles of political, religious or corporate power, or whatever their equivalent may be in an extraterrestrial culture, and unanimously agreed not to interfere with alien worlds.

    Or the reason may be as what I pointed out earlier; directed Panspermia may have occurred already and we haven’t seen signs of it because all life on other planets, including Earth may share the same DNA. The only way we’ll know is to find life on a statistically significant sample of randomly distributed alien planets, capture a bacterial sample and generate a genetic map, then run tests to determine what nucleic acids make up its DNA. If all results come up reasonably similar, allowing for local mutations to a particular planet’s environment, then we’d have sufficient evidence to claim directed Panspermia is a possibility. Of course, we still couldn’t rule out the possibility that perhaps viable DNA can be spontaneously assembled using only the four nucleotides found in all terrestrial life forms; i.e. terrestrial DNA may not be that unique, just as the forces of electromagnetism and gravity are not unique to the Earth.

    All of my above comments are, for the moment, speculative until we discover forms of life on an exoplanet we can study at the molecular level.

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  24. 24. RichardHoover 12:03 pm 10/18/2012


    Science is based on evidence, observational data, facts, logic and reason. Politics is based on consensus of the community. During the past 15 years, I have presented high resolution ESEM and FESEM images and spectral data revealing the elemental composition of trichomic filaments encased in carbonaceous sheaths and embedded in the rock matrix of a large number of different carbonaceous meteorites. Academician Alexei Rozanov, Director of the Paleontological Institute of the Russian Academy of Sciences, has independently discovered similar filaments in different samples of these meteorites. He has also interpreted them as the fossilized and permineralized remains of Cyanobacteria and other filamentous trichroic prokaryotes.

    There is solid scientific proof from our work as well as that of a host of other distinguished researchers that these meteorites are not contaminated by modern microorganisms. If these stones were contaminated, they would have to contain
    20 protein amino acids, all 5 nuucleobases, ribose, deoxyribose and other surgars, chlorine, ATP, NADH and many other life critical biomolecules that are present in all living and recently dead organisms — They do not contain these biomolecules and therefore have not been invaded by Cyanobacteria after they landed on Earth.

    Caleb, I have studied diatoms and cyanobacteria for almost half a century and do have the ability to identify and classify these organisms as well as many other bacteria and microfossils. Furthermore my images and data have been e
    examined by many of the worlds leading authorities on meteoritics, cosmochemistry, cyanobacteria and micropaleontology — Rosemari Rippka Herdman, Academician Georgi Zavarzin, Academician Michael Ivanov, Academician Alexei Rozanov, Academician Eric Galimov and many others. All of these extremely knowledgeable scientists have also agreed one of them that these images are of the remains of trichromic filamentous prokaryotic microorganisms.

    Caleb, I do not know of a single paper in the scientific literature that has provided an alternate explanation for the data I have openly presented. Just saying -The communities response to the evidence is not ‘good’ ” does not constitute a scientific argument. The “community” has also never provided a response as to what is not ‘good’ about the data. Also, do these members of the “community” have a knowledge base that allows them to access the validity of the data. The opinion of a microbiologist regarding the validity of the recent datapublished on evidence for the “god particle” would not carry very much weight. I similar manner, the opinion of members of the “community” who have never studied Cyanobacteria should not be afforded great merit.

    I welcome a solid debate, based on science. If anyone can set forward an alternate interpretation for my data based on sound evidence (for example if someone could name a species of a mineral that grows crystals that exhibit the morphology, size and size range and chemical compositions of these filaments) then I would be delighted to re-examine my interpretation. Of course, I would also ask them to provide me an example of this mystery mineral, so that I could put in in the FESEM and find and perform EDAX analysis on these mineral crystals myself.

    Caleb, I would personally ask you to re-read the JOC article in light of my comments and away from the fog of the tremendous howl and cry that was thrown up (without any supporting data) by many after these results were published. You may want to also look at some of the other papers. You may also want to look at images of Calothrix and other filamentous cyanobacteria that are easily found on the Web to appreciate the strength of my argument. By he way, the JOC paper was not a “discovery paper” but more of a review article.

    Caleb, Please let me know if your opinion remains the same after devoting some more thought to the matter. I am absolutely certain that these images are of filamentous microorganisms that lifted and died on the parent bodies of these meteorites long before these stones entered the Earth’s atmosphere. Hence, extraterrestrial life exists and the proof of it is to be found in the fossilized remains and the complex life-critical biomolecules that exist in these meteorites.


    Richard B. Hoover

    does not exist a single paper in the scientific literature

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  25. 25. savvov 2:43 pm 10/18/2012

    “the notion of panspermia – the transferral of vital organisms between planets”, is unpersuasively, at the same time characteristics of planets of Solar system have proved planetary panspermia – between System of planets and Solar system that has in turn allowed to prove what changes have taken place on the Earth from the moment of occurrence in Solar system, and in what degree kinds of fauna have adapted to these changes and homo sapiens. In more detail on a site ” Dynamic model of the globe of a planet the Earth

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  26. 26. Combinator 4:17 pm 10/18/2012

    Dear Mr. Richard Hoover,

    may be it will interesting for you to know that few months ago I had wrote (on Russian) the paper “Possible traces of life in meteorites” where described very briefly your biography and your results: It looks like that for many peoples this is psychologically very difficult to accept the idea that Earth may be not the place where life was originated like in the Middle Ages it was psychologically difficult for peoples accept the idea that Earth is not the center of Universe. When I discuss panspermia option with some people with my list of arguments they typically even do not try to find counterarguments, but just respond “this list is not enough you should find more arguments to consider panspermia seriously…”. Do you know why during last decade nobody try to estimate the age of LUCA (Last Universal Common Ascender of the all live organisms on Earth) by standard molecular clock methods? The answer is very simple – formally calculated this age occur to be larger than age of Earth! So seems they prefer just “close the eyes” on this problem. Strange (for the abiotically synthesized amino acids) isotopic carbon distributions between L and D forms of alanine in the Murchison meteorite I am already noticed in my previous post. It is also indicative that boundary between formations with traces of life (microfossils, stromatolites) and formations without them is very sharp. Deeper than 3.5 bya we have nothing and after this date there is a lot of sites with clear signs of complex microbial mats in at least two continents – Africa and Australia. So where is signs of all previous stages of evolution?
    I believe that like it finally happened with theory of continental drift soon or late theory which initially was considered by many peoples as strange and counterintuitive will win in the light of objective arguments!

    Sorry for my very poor English.

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  27. 27. jdaw1 5:30 pm 10/18/2012

    A hardy single-celled creature, having travelled the cosmos, lands somewhere like Earth. It evolves into something that copes well with a wet 20°C. Later, much later, a collision then scatters this into space. Scatters what? Not the hardy traveller, but its much ‘softer’ capable-of-being-numerous-here descendants.

    Yes, the next in the chain will be a descendant of the hardiest of those in a few m³ of water. So Caleb A. Scharf’s description ignores the many steps of being, of becoming, the fittest life somewhere with lots of life.

    Link to this
  28. 28. GreenMind 6:59 pm 10/18/2012

    Caleb writes: “Now, we might argue that there are organisms on Earth that could fit the bill, and could represent the most direct descendents of these ancient interlopers. Slow-living, low-metabolism chemoautotrophs abound, and our knowledge about these proverbial bottom-feeders is still very limited.”

    That sounds very plausible. To me the answer lies in the nature of those chemoautotrophs. Studies have found bacteria exactly like the ones you describe deep inside the earth, metabolizing chemicals in the rock. If a very big meteor hit the earth, sending large fragments of rock from deep in the earth into space, they may survive in the deep freeze by being protected from radiation by the rock.

    Caleb also writes: “But the problem, and the potential paradox, is that if evolved galactic panspermia is real it’ll be capable of living just about everywhere. There should be stuff on the Moon, Mars, Europa, Ganymede, Titan, Enceladus, even minor planets and cometary nuclei. Every icy nook and cranny in our solar system should be a veritable paradise for these ultra-tough lifeforms, honed by natural selection to make the most of appalling conditions. So if galactic panspermia exists why haven’t we noticed it yet?”

    No paradox. After the big rock filled with bacteria lands on a planet with no oxygen on the surface (oxygen is lethal to them), they will colonize the rocks and spread deep underneath the planetary surface, just like on the planet they came from. The surface of planets can be a harsh place, with all kinds of radiation, solar flares, big meteor strikes, mega-volcanoes, X-ray bursts, supernovae, etc. that can sterilize the outer layer. But they are safe down deep in the crust. So you are right. Every nook and cranny on the planets should be filled with life. All we have to do is dig. What, you were expecting something bigger than bacteria?

    I once read an article about all the dangers that lurk in space that can wipe out life on planets. Thing is, all the dangers were for life on the surface of planets, not buried inside. Planets in the galactic core may be too dangerous for surface life while life under the surface thrives. Perhaps the answer to Fermi’s Paradox is that surface life just gets wiped out too often, and we are just lucky (so far). It helps to be far from the galactic center (in the galactic Goldilocks zone), and to have so much dust between us and the center, and have so many gas giants in our system sweeping up debris, and not having another star nearby disturbing the Oort Cloud or flinging planets out into the interstellar void. And not having a supernova go off in our neighborhood for awhile. Just lucky. It might be easy for an astrophysicist to calculate how lucky you have to be to have a big enough window of opportunity to have an intelligent species evolve in between sterilizations.

    And then, of course, as soon as intelligent life evolves, it eats everything on its planet and dies out.

    Link to this
  29. 29. stevewriter 7:10 pm 10/18/2012

    Here’s my take on Panspermia. Earth’s Human beings are an example of one of many fruiting bodies that the pattern of life creates on various planets or moons to carry the living pattern elsewhere in the universe. The pattern doesn’t think, but it might work something like:

    The human breast swells with pride at the power of our reason and technical skill, which has enabled us to launch vehicles into space. There is advantage to the living pattern for humans to be inclined to carry life to other worlds. It does not matter if the human individuals are able to survive long-term on those other worlds so long as they carry the pattern there. We will carry the pattern with us and in us, but we may also carry it intentionally.

    For example, it is likely that if humans were to go to Europa, to start a colony, our technical skill would fail before the daunting task of building a human civilization in such a cold place. However, simply by being there and being successful for a time we may provide the pattern of life with the opportunity seed that moon. Bacteria in our waste, or on our body, or special cells we build using our intelligence may be able to live on the moon. Now, crank out a few billion years of patten evolution on Europa, and there may appear another kind of fruiting body that rationally, or by some other means enables the pattern to spread further into the universe.

    There is survival advantage for humans to feel important, but the feeling is not necessarily based in reality. Rational species may be a transitory kind that the pattern of life brings into existence for a time. Reason may be something that is unstable and disappears after fulfilling its purpose.

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  30. 30. GreenMind 7:13 pm 10/18/2012

    I think we may all have been missing the obvious. It may not be meteor strikes that launches big rocks with life in them into space to drift for millions of years between star systems. It may just be that a star system swings by another star and a planet with life on it gets thrown out of the system into space. Earth stays molten inside mostly because of radioactive decay, so the bacteria inside could live indefinitely during the voyage between stars. Then the planet could zip through another planetary system, get hit by a local asteroid at high speed, leave a few chunks of itself to colonize the locals planets, and then fly on through to the next system. Presto! Just one planet could spread archaeobacteria to a lot of star systems over a billion or two years.

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  31. 31. GreenMind 7:19 pm 10/18/2012

    jdaw1, it looks to me that those organisms that evolved in the wet 20 degree environment are not the ones that will survive the trip to the next star. I think the ones embedded in hot dry rocks are more likely to survive the meteor strike, or whatever it is that carries it into space.

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  32. 32. Caleb A. Scharf in reply to Caleb A. Scharf 12:40 pm 10/21/2012


    By way of a coda to all these comments, and hopefully some useful feedback. I did look again at the JOC paper. As a physicist and astronomer here is my #1 question, that I find to be the biggest stumbling block to accepting the overarching hypothesis. Regardless of the structures and compositions that you are finding in these samples I again and again come back to asking about how one establishes the *precise* effect of atmospheric entry, passage through 60 miles of microbe and chemistry laden atmosphere (presumably experiencing high pressure gradients, shock waves, electrostatic changes), impact on the ground, and a wide range of documented, undocumented, and anecdotal information about the sample collection, storage, and chemical environment. While it is fine to provide support for the notion that there has been no terrestrial contamination or alteration by referring to things like the friable nature of the rocks or eye-witness observations of coatings or thermal properties, I don’t think this is sufficient to prove beyond a shadow of a doubt that the interiors are genuinely pristine and unaltered. Unfortunately the ideal control experiment may be impossible to perform – this would be to drop an entirely sterile piece of carbonaceous meteorite through the Earth’s atmosphere to replicate all of the conditions (including decades of samples sitting around in a variety of storage states) and to then perform the same analyses to see what’s inside (before and after).

    I’m afraid I keep coming back to this, and I suspect other people do too. It doesn’t matter what secondary evidence there is (weird chemical compositions, things that look like fossils rather than recently extant microorganisms etc etc) – the initial ‘experiment’ is just too uncontrolled – which is no fault of yours, but it does present a major challenge to find a way to deal with. Capturing a carbonaceous chondrite *in situ* (interplanetary space), would seem to be the solution – or sampling cometary nuclei. Hardly easy, but then again it would be an incredible scientific resource.

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  33. 33. brigklyce 6:55 pm 10/21/2012

    Caleb, thanks for remaining engaged. But it still sounds like you have not read the presentation of the evidence. If you have, you must suppose that a few seconds of atmospheric entry could somehow affect the meteorite such that subsequent earthly contaminants, within the next century-and-a half, would lose all of their nitrogen and phosphorus, and half of their amino acids, while the others became well racemized. These processes take tens of thousands to millions of years in nature. Atmospheric entry could cause all of these processes to accelerate by orders of magnitude? You seem eager to dismiss the whole thing. Why not really take a probing look?

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  34. 34. Caleb A. Scharf in reply to Caleb A. Scharf 7:08 pm 10/21/2012

    No. The onus is not on me (or anyone else who is skeptical) to re-read the presentation (and I did, as I said), the onus is on the scientists making the claims to address people’s critical questions with further evidence or analysis. Dismissing my skepticism as ‘you must suppose that….’ is NOT how this works, at least not in peer-reviewed scientific work. Until I can be shown a control experiment or observation that explicitly demonstrates that there is no alteration, no contamination, nothing unexpected happening between interplanetary space and placing the samples on a modern sterile lab bench I’m afraid I must remain unconvinced. Time and time again the ‘obvious’ in science turns out to be wrong, and in this case that could cut both ways – both pro- and con- assumptions could be false.

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  35. 35. brigklyce 10:25 pm 10/21/2012

    Caleb, I do not understand your scepticism. I believe you have been shown evidence of biology, for which contamination is ruled out by a detailed chemical analysis. If you wish to rule it back in, I think you must be specific, not vague. (What, exactly, are the critical questions you mention?) If I misunderstood what you must suppose, then what do you suppose, beyond generalities, that might produce the fossils?

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  36. 36. Combinator 1:40 am 10/22/2012

    Well with logic like “Until I can be shown a control experiment or observation that explicitly demonstrates that there is no alteration, no contamination, nothing unexpected happening between interplanetary space and placing the samples on a modern sterile lab bench I’m afraid I must remain unconvinced” I am guess that we should dismiss all evidences of Archean and Proterozoic life because obviously nobody can show a control experiment or observation that explicitly demonstrates that there is no alteration, no contamination, nothing unexpected happening between time when corresponding rocks was formed and now.
    Anyway I think that most promising way to dissuade skeptics will be deliver some set of carbonaceous chondrites meteorites from the Moon. Plenty of them should be there and technically this mission looks not very complex and should be not expensive.

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  37. 37. brigklyce 9:14 am 10/22/2012

    Caleb, you wrote, “the onus is on the scientists making the claims to address people’s critical questions with further evidence or analysis.” There were two reasonable objections to the fossils — 1) they are not biological, or 2) they are Earthly contaminants. Hoover has very methodically met those objections, especially the more serious, latter one. The onus has passed back to the objectors.

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  38. 38. bucketofsquid 5:58 pm 10/22/2012

    I have no idea if panspermia has or has not occurred. I do know that I will be very disappointed if in the remainder of my life, we don’t put colonies on the moon and mars and start the process of moving further out with an eye to eventual interstellar planet building (including from scratch or altering orbits into the life supporting zone), geoforming (creating life friendly topography) and biosphere creation. I won’t use the term Terraforming because that would involve changing gravity to be Earth normal and require all of the same species which may not be feasible.

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  39. 39. verdai 4:00 pm 10/23/2012

    Y E S

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  40. 40. Daniel35 4:37 pm 10/26/2012

    The bottom line is that we have life here and we don’t know for sure whether it’s elsewhere or where it started. We’re getting into a stage of looking further elsewhere. But finding it won’t likely answer the final question of where it started or if it can start in even more diverse conditions. That’s life. Get used to it.

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  41. 41. ann onimus 12:41 pm 11/21/2012

    Interesting ideas, Stevewriter.

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  42. 42. Kevin Keogh 6:35 pm 12/6/2012

    Let’s assume there are different self-replicating chemical systems competing with each other to exploit the photochemical energy of stars, planets and moons throughout our galaxy.

    The fact that there are 5 million-trillion-trillion microbes on Earth and that many of these microbes have the ability to survive long journeys in space to infect other planets and moons suggests that our planet’s dominant self-replicating chemical system (microbial life) may be one of the most evolutionarily successful, at least in our little corner of the galaxy.

    However, in this expanded evolutionary game, success would not only entail the ability to infest a single planet or moon, but also the ability to infest nearby (and later distant) planets and moons as well.

    The most conservative mechanism of galactic infestation would be projectile panspermia in which uninfested (or infested) meteorites collide with infested planets and moons, knocking loose infested pieces that later impact other uninfested planets and moons to spread microbial life. The feasibility of this mechanism, at least on an interplanetary scale, is now well recognized by astrobiologists.

    A second, more powerful infestation model would be for some of the microbes that are most successful on a galactic evolutionary scale to have evolved the ability to terraform the planets and moons they infest, resulting in huge volcanoes that spew countless microbes (along with the requisite protective dust/rock shielding) directly into interplanetary and interstellar space.

    A third, even more controversial mechanism would be for these microbes to have evolved the ability to cooperatively assemble into giant, sentient self-replicating transport vehicles on the surfaces of select planets that these microbes have long since terraformed to allow for the proliferation of such transport vehicles. The genetic instructions to build such creatures would conceivably already be floating around the galaxy, depending on the previous galactic evolutionary success of these creatures. But consider that galactic evolutionary success would be measured to a large degree by relative levels of interplanetary and interstellar expansion. What sentient transport vehicles would be inclined to invest the full force of their entire society just to leave the relative paradise of their evolutionary development in order to colonize far less hospitable neighboring planets and moons?

    What could spur these sentient transport vehicles to invest so much societal effort to accomplish such a daunting, laborious and physically unappealing task? Perhaps as certain varieties of giant sentient transport vehicles develop the technological ability to exploit by combustion the huge quantities of carbon that subterranean microbes have so temptingly sequestered just below the surface of their home planets, this process inevitably sets into motion the necessary motivation for interplanetary expansion.

    Is this the deeper meaning of the Garden of Eden myth?

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  43. 43. RichardHoover 4:20 am 01/6/2013


    You are a physicist and obviously out of your element. Paleontologists do not do “experiments” in the same sense of those done in particle physics. They observe the remains of ancient life forms as exhibited in bones, permineralized fossils or other tracks and trace evidence of biological activity. While no one has ever seen a living trilobite or dinosaur, there can be no doubt that they were once alive based on the fossil remains that are found. In the same way, micropaleontologists have come to understand much about the nature and evolution of the oceans, atmosphere, and life on our planet by the study of fossils of diatoms, forams, radiolaria, Cyanobacteria, stromatolites, etc. I did not conduct an experiment. I simply broke open the meteorites and observed what was present on the interior of the uncoated stones using advanced Environmental and Field Emission Scanning Electron Microscopes.

    Many of the meteorites were absolutely devoid of structures with morpholocal and chemical properties indicative of recent or ancient biological activity. Not a single one of the stony or nickel iron meteorites studied contained any evidence whatsoever of fossil remains—although they had passed through the same atmosphere. Some of the carbonaceous chondrites are also devoid of recognizable filaments that could be interpreted as the remains of living organisms (fossils). But in Murchison and Orgueil, these remains are there for anyone to find who will devote the time for a proper search. However, to conduct a search that has any meaning, it is essential that the individual have some knowledge regarding the size, size range and detailed morphological characteristics of living and fossil microorganisms that exist in the oceans, seas tidal basins, rivers and ponds on Earth. That means they should have experience in observing living and fossil microorganisms in visible light and scanning electron microscopes. By way of example, consider this —
    Show a photo of the tracks produced by an experiment carried out with collisions of relativistic particles in the Large Hadron Collider to a competent particle physicist and he will probably be able to immediately tell you the names of the diverse zoo of mesons, quarks and other particles responsible for the many coiling tracks captured in the image. Show the same photo to a microbiologist with no training in particle physics. Ask him to identify the various particles and see how accurate his answers may be.

    Caleb, you apparently did not understand the significance of the EDS data in my paper regarding whether or not the filaments that can be recognized as the remains of Cyanobacteria and other trichomic prokaryotes are indigenous microfossils or modern contaminants that entered the stones after they landed on Earth. The answer in in the fact that the meteorite filaments typically do not contain detectable levels of NITROGEN. The cells of all living organisms (and even dead organisms, that are less than a few hundred thousand years old assuming they have not been cooked to charcoal on a fire) contain nitrogen at levels between 2% and 18% atomic. If these filaments were modern biological contaminants — they would have nitrogen levels that could be detected bt the EDS. They do not — Hence they are not recent contaminants. Furthermore, if these stones were contaminated by modern bacteria or Cyanobacteria they would contain all 20 amino acids and all five nucleobases and the sugars ribose and deoxyribose that are present in every living cell. These are also not found in the carbonaceous meteorites providing clear and convincing proof that the meteorites have NOT been contaminated with Earth Life after entry into our atmosphere. Caleb, these are facts that are well established and widely known by all scientists who have studied the biochemistry of carbonaceous meteorites.

    If you want to dismiss the filaments that are present in these stones as modern biological contaminants — then you must explain how these contaminants have lost their nitrogen and the life critical biomolecules that are missing from the meteorites. This is the rock solid evidence upon which I base my claim that the filaments can not be dismissed as modern contaminants. If you or others want to claim that they are contaminants—then you are obligated to explain the large body of observed biochemistry of the carbonaceous meteorites that has been established over the past century and a half by scientists from all over the world that provides solid evidence that the interiors of these pristine stones contain indigenous extraterrestrial amino acids and nucleobases and have not been contaminated by Earthly bacteria as they passed through the atmosphere and landed on Earth.


    Richard B. Hoover
    January 6, 2013

    Link to this
  44. 44. bsmith821 6:12 pm 05/16/2013

    Dear Caleb Scharf: For many years I have been following the Panspermia theory incubated at the University where you received your PhD (ie University of Cambridge, UK) by the great scientist Sir Fred Hoyle and his prodigy Dr Chandra Wikramasinghe.

    Since last December 2012, I have been intrigued by the Polonnaruwa Meteorite discovery and the two analyses performed by Prof Wikramasignhe’s cross discipline team. The results were published in the much maligned Journal of Cosmology. I have been disturbed at the poor quality of the public criticisms especially by WIKIPEDIA and by so called experts who seem to have very narrow fields of expertise.

    I took the time to analyze the experiments documented in the two papers. In summary there were 17 experiments involving many disciplines and using much equipment:
    • Jan 2013 paper – 11 experiments
    • Mar 2013 paper – 6 experiments

    Equipment Needed to reproduce all 17 experiments :
    . Light Microscope
    . EDX
    . Environmental Scanning Electron Microscope
    . Triple Oxygen Isotope Analysis – Thermo MAT 253 spectrometer
    . Scanning Electron Microscope (SEM) – Philips XL30 FEG ESEM
    . Hitachi S-3700N Field Emission Scanning Electron Microscope
    . FTIR -diamond ATR

    I have been trying to motivate and help fund a team of scientists here in Canada to re-run these 17 experiments covered in the 2 papers. The intent is to reproduce all the results and then to assess if the results do indeed support Prof Chandra Wickramasinghe’s Panspermia hypothesis. Running the experiments on two sources (1) meteorite provided by Prof Wikramasinghe (he has kindly offered to support such a peer review) (2) the rock that was deemed not to be a meteorite (Professor of Geology Athula Senarathna of the University of Peradeniya who carried out a research on the alleged meteorite and has said that “there could not be any truth in Prof. Chandra Wickramasinghe’s claim”.
    I am finding creating such a project (peer review)a challenge as nowhere are all the required scientific instruments available in one place, nor is it easy to find a scientist (or grad student) willing to temporarily drop their own work.
    Perhaps you can guide me on this.

    Surely there is an astrobiologist (with available Grad student) somewhere willing to put a little time into this project? Especially if we could get the funding to pay them.

    I am of the opinion that the diatoms ARE proven to be there. The issue is “contamination”. BUT my understanding is that the NASA FTIR test and the EDX tests of March 2013 provide clear and convincing evidence that the Polonnaruwa meteorite contains ancient remains of extinct marine algae which are also indigenous to the stones and not the result of post-arrival microbial contaminants.

    I beg you – Caleb Scharf (and a recommended Grad Student)
    - to consider taking on this project which would attempt to recreate the results and reassess the conclusions.
    Best wishes
    Bill Smith

    Link to this
  45. 45. bsmith821 11:39 am 05/17/2013

    Note to Richard Hoover : your explanation on contamination sounds reasonable to a layman. In summary : What are the detectable levels of NITROGEN? The cells of all living organisms (and even dead organisms, that are less than a few hundred thousand years old assuming they have not been cooked to charcoal on a fire) contain nitrogen at levels between 2% and 18% atomic. If these filaments were modern biological contaminants — they would have nitrogen levels that could be detected by the EDS. They do not — Hence they are not recent contaminants. Furthermore, if these stones were contaminated by modern bacteria or Cyanobacteria they would contain all 20 amino acids and all five nucleobases and the sugars ribose and deoxyribose that are present in every living cell. These are also not found in the carbonaceous meteorites providing clear and convincing proof that the meteorites have NOT been contaminated with Earth Life after entry into our atmosphere.

    Caleb Scharf : how do you counter Hoover’s explanation of this evidence?

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  46. 46. bsmith821 2:04 pm 05/17/2013

    Caleb : you make this point :

    The onus is not on me (or anyone else who is skeptical) to re-read the presentation (and I did, as I said), the onus is on the scientists making the claims to address people’s critical questions with further evidence or analysis. Dismissing my skepticism as ‘you must suppose that….’ is NOT how this works, at least not in peer-reviewed scientific work. Until I can be shown a control experiment or observation that explicitly demonstrates that there is no alteration, no contamination, nothing unexpected happening between interplanetary space and placing the samples on a modern sterile lab bench I’m afraid I must remain unconvinced. Time and time again the ‘obvious’ in science turns out to be wrong, and in this case that could cut both ways – both pro- and con- assumptions could be false.

    It seems you are likely unwilling to accept the results of the FTIR and EDX tests applied to the Polonnaruwa Meteorite tests from March 2013.
    Ie am I correct in inferring you do NOT believe that we can prove “non contamination” using these 2 tests?

    The issue is “contamination”. BUT my understanding is that the NASA FTIR test and the EDX tests of March 2013 provide clear and convincing evidence that the Polonnaruwa meteorite contains ancient remains of extinct marine algae which are also indigenous to the stones and not the result of post-arrival microbial contaminants.

    I would love to know exactly what your objection to these 2 tests are.

    Trying to understand your position : do you believe these 2 tests are necessary BUT NOT sufficient for a proof of non-contamination?

    Link to this

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