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Thread: Evotheory and life in the space

  1. #61
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    Quote Originally Posted by Olli S View Post
    From the fact that we don't know how probable does not follow that the probability is zero.
    Consider the concept that 'Earth life' may well be the sole attribute that distinguishes Earth from every other planet in the universe.
    Following your logic, until that concept can be dismissed with objective evidence, your 'probability' of finding that life beyond Earth, remains as being zero.

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    Quote Originally Posted by msollot View Post
    Maybe they buried an obelisk on the moon. Perhaps the dimensions of the obelisk can be reduced to 1X2X3, and when exposed to sunlight, will emit a signal that our civilization has advanced enough for contact by this extra-terrestrial civilization.

    Maybe this has all happened before, and will happen again.
    Science is not based on a myth and the director and screenwriter for that film came right out and called it a myth. Science falsifies myths so, in that sense, it does use them by holding them up to scrutiny. The OP seems to hold the view that the earliest stars in the universe were just like our Sun while evidence from spectroscopy suggests that there were too few metals present in stars during early times to be comparable to our star.

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    Quote Originally Posted by Selfsim View Post
    Consider the concept that 'Earth life' may well be the sole attribute that distinguishes Earth from every other planet in the universe.
    As a thought-experiment, I'm quite willing to entertain the idea that Earth is the only life-bearing planet in the universe. However, if that is the case, it raises questions such as:

    1. On other planets where there are diverse carbon-chain compounds, liquid water, and energy sources, what sort of systems emerge? If not life, what?
    2. Just why has the behaviour of carbon-chain compounds been so different here on Earth, compared to every other planet?

    If you could suggest plausible answers to these questions, then the scenario you've put forward might be considered plausible too.

  4. #64
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    Quote Originally Posted by Selfsim View Post
    Following your logic, until that concept can be dismissed with objective evidence, your 'probability' of finding that life beyond Earth, remains as being zero.
    The probability of finding life beyond Earth would only be zero if it were somehow established, beyond all doubt, that there is none. (Or none within range of any conceivable observation.)
    Last edited by Colin Robinson; 2017-Mar-05 at 03:07 AM.

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    Quote Originally Posted by Colin Robinson View Post
    As a thought-experiment, I'm quite willing to entertain the idea that Earth is the only life-bearing planet in the universe. However, if that is the case, it raises questions such as:

    1. On other planets where there are diverse carbon-chain compounds, liquid water, and energy sources, what sort of systems emerge? If not life, what?

    Unknown.

    Quote Originally Posted by Colin Robinson
    2. Just why has the behaviour of carbon-chain compounds been so different here on Earth, compared to every other planet?
    Unknown.

    Quote Originally Posted by Colin Robinson
    If you could suggest plausible answers to these questions, then the scenario you've put forward might be considered plausible too
    Describe the objective test whose result returns an unequivocal value of 'plausible'. If there is none .. then it ain't science.

    Quote Originally Posted by Colin Robinson
    The probability of finding life beyond Earth would only be zero if it were somehow established, beyond all doubt, that there is none. (Or none within range of any conceivable observation.)
    My point is that IN THE LIGHT OF NOT KNOWING, it is the choice of adopting a 'worldview' that Earth-life may well be the distinguishing attribute which makes Earth stand out from all the other planets in the universe. Coming from this worldview (in the absence of objective evidence to the contrary), assigning a probability of zero as a prior, is perfectly valid (and as equally valid as assigning a probability of one when coming from the opposite world view). Discovering Earth-life on some other planet however, would invalidate the above mentioned worldview.

    'Tis one's worldview which is driving the assignment of prior probability .. and nothing else.

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    Quote Originally Posted by Selfsim View Post
    Describe the objective test whose result returns an unequivocal value of 'plausible'. If there is none .. then it ain't science.
    That's rather like saying: Direct me to the pharmacy where I can buy an Occam's Razor.

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    Quote Originally Posted by Selfsim View Post
    My point is that IN THE LIGHT OF NOT KNOWING, it is the choice of adopting a 'worldview' that Earth-life may well be the distinguishing attribute which makes Earth stand out from all the other planets in the universe. Coming from this worldview (in the absence of objective evidence to the contrary), assigning a probability of zero as a prior, is perfectly valid (and as equally valid as assigning a probability of one when coming from the opposite world view). Discovering Earth-life on some other planet however, would invalidate the above mentioned worldview.

    'Tis one's worldview which is driving the assignment of prior probability .. and nothing else.
    Of course Earth life is found on Earth. It is a truism. As alien life might possibly be found on an alien world. Or not, as the case may be.
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    Quote Originally Posted by Selfsim View Post
    Following your logic, until that concept can be dismissed with objective evidence, your 'probability' of finding that life beyond Earth, remains as being zero.
    No, by your own statements, the probability is and will remain unknown, until and unless actual ET life is discovered.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Olli S View Post
    So, the theory of evolution or the broader science is not working in other planets of the universe? Science is only working on the earth in your mind. This proof here is scientific but only probable, not necessary. From theories follows things. You have right that there is no other evidence yet in the natural sciences. And they are not the only sciences. Logic is also a science.
    The theory of evolution has nothing to do with whether life exists on other planets. It covers only living things that reproduce. If life emerged on other worlds, that life too would evolve.

    Logic is a manipulation of symbols, nothing more. It is often useful in science, but logic by itself is not a science. Science always requires testable, repeatable evidence, that is part of the scientific process. Science is first and foremost an evidence-based discipline.
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  10. #70
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    Quote Originally Posted by Noclevername View Post
    The theory of evolution has nothing to do with whether life exists on other planets. It covers only living things that reproduce.
    Actually there is a serious argument that evolution began before life that it began with autocatalysts, chemical systems which reproduce, but are far simpler than the simplest living cell. See the paper Towards an evolutionary theory of the origin of life by Robert Pascal, Addy Pross and John D. Sutherland.

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    The evolution theory has everything to do with the matter of the life elsewhere. The theory supposes that life has become from the matter and energy. If this is not in the theory, how the life has emerged? If it is not a theory of the beginning of life in the earth, what then is the theory of this emergence? Normally it is called the theory of evolution. And whatever its name, this is how science thinks this matter.

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    Quote Originally Posted by Strange View Post
    No one said it does. But the fact we don't know means you cannot say that "it is probable". All you can say is "we don't know".
    Other facts are the life on the earth and the evolution theory, or the theory that life has emerged from matter in the earth. And the large universe with so much times and places. It does not follow only from the fact that we don't know how probable.

  13. #73
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    Quote Originally Posted by Olli S View Post
    The evolution theory has everything to do with the matter of the life elsewhere. The theory supposes that life has become from the matter and energy. If this is not in the theory, how the life has emerged?
    You are confusing Evolution with Abiogenesis.
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  14. #74
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    Quote Originally Posted by PetersCreek View Post
    You are confusing Evolution with Abiogenesis.
    You are evidently not aware of recent papers by John D. Sutherland and others which argue that abiogenesis was an evolutionary process. See the link in post #70 of this thread.

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    Quote Originally Posted by Colin Robinson View Post
    You are evidently not aware of recent papers by John D. Sutherland and others which argue that abiogenesis was an evolutionary process. See the link in post #70 of this thread.
    I haven't read the paper but I think abiogenesis is presumed to require some early form of chemical self-organisation and subsequent evolution (using the 'small e' form of the word ). Coalescence of water-phobic lipids into closed systems where the internal chemistry is isolated from the environment - or some such.

    So yeah, I think there's a blurred line here between evolutionary life and evolutionary non-life.
    Last edited by DaveC426913; 2017-Mar-05 at 08:44 PM.

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    Quote Originally Posted by Olli S View Post
    The evolution theory has everything to do with the matter of the life elsewhere. The theory supposes that life has become from the matter and energy. If this is not in the theory, how the life has emerged? If it is not a theory of the beginning of life in the earth, what then is the theory of this emergence? Normally it is called the theory of evolution. And whatever its name, this is how science thinks this matter.
    As noted, it is abiogenesis. But we don't have a theory of that yet.

    And it still doesn't tell us anything about how probably it is.
    Last edited by Strange; 2017-Mar-05 at 09:08 PM.

  17. #77
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    Quote Originally Posted by Colin Robinson View Post
    You are evidently not aware of recent papers by John D. Sutherland and others which argue that abiogenesis was an evolutionary process. See the link in post #70 of this thread.
    I think it is pretty clear (and always has been) that abiogenesis must involve some sort of chemical evolution (including selection of successful chemical routes). But that is very different from "Darwinian" or biological evolution involving genes and the frequencies of alleles. Maybe one day they will be merged into a single discipline, but we are a very long way from that currently.

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    Quote Originally Posted by DaveC426913 View Post
    I haven't read the paper but I think abiogenesis is presumed to require some early form of chemical self-organisation and subsequent evolution (using the 'small e' form of the word ). Coalescence of water-phobic lipids into closed systems where the internal chemistry is isolated from the environment - or some such.
    They're exploring the idea that simple chemical systems (autocatalysts) can compete for resources, and undergoing natural selection, in a similar way to living things. They quote an earlier paper by S. Lifson:

    "His analyses demonstrated that two autocatalytic loops, when competing for a single resource provided at a constant rate, evolve towards the extinction of the less efficient one in a similar manner to that for natural selection. This selective behaviour is therefore not specific to living organisms but can be extended to all entities capable of reproduction."

    They go on to look at the thermodynamic conditions in which this can happen. For instance, it would not happen in a mixture of compounds at equilibrium. There has to be a source of free energy, such as sunlight and/or an energetic chemical substance such as hydrogen cyanide.

    So yeah, I think there's a blurred line here between evolutionary life and evolutionary non-life.
    Yes, it's starting to look as blurry as the line between humans and other primates...

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    Quote Originally Posted by msollot View Post
    Maybe they buried an obelisk on the moon. Perhaps the dimensions of the obelisk can be reduced to 1X2X3, and when exposed to sunlight, will emit a signal that our civilization has advanced enough for contact by this extra-terrestrial civilization.

    Maybe this has all happened before, and will happen again.
    That's absurd! In order for an obelisk to transmit such a signal, it would obviously have to be reduced to 1X4X9.

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    My belief is in panspermia. So many of the elements on our planet came from elsewhere, why not the building blocks of life?

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    Quote Originally Posted by Red5 View Post
    My belief is in panspermia. So many of the elements on our planet came from elsewhere, why not the building blocks of life?
    But keep in mind that Panspermia doesn't just say the building blocks of life came from space (a strong possibility given what we know), it says life itself came to Earth from space (a hypothesis for which we have no data). Without organization into the self replicating molecular machines that make up us and our planetary cohorts, it's not life, just unbuilt blocks.

    My own take is that early Earth was a giant chem lab, oceans of liquid water carrying complex molecules all over between various conditions like tide pools, mud, dark smoker vents, volcanoes, etc.
    Last edited by Noclevername; 2017-Mar-09 at 01:58 PM.
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    Quote Originally Posted by Noclevername View Post
    But keep in mind that Panspermia doesn't just say the building blocks of life came from space (a strong possibility given what we know), it says life itself came to Earth from space (a hypothesis for which we have no data). Without organization into the self replicating molecular machines that make up us and our planetary cohorts, it's not life, just unbuilt blocks.
    Excellent point, and I was unclear in my post. Thank you.

    I believe there's a strong chance life came from elsewhere, and the conditions were ripe on Earth for evolution. Other planets/moons would have received he same "seeds" but not necessarily developed them.

  23. #83
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    Quote Originally Posted by Red5 View Post
    I believe there's a strong chance life came from elsewhere
    Never understood this hypothesis. How does it solve anything?
    It simply means the same questions must be asked about some other rock somewhere else.

    The only difference it makes at all, is that it removes the time constraint of the 4.5 billion year age of the Earth.

  24. #84
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    Quote Originally Posted by Red5 View Post
    Excellent point, and I was unclear in my post. Thank you.

    I believe there's a strong chance life came from elsewhere, and the conditions were ripe on Earth for evolution. Other planets/moons would have received he same "seeds" but not necessarily developed them.
    Where else, and why do you think that?
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    Quote Originally Posted by DaveC426913 View Post
    Never understood this hypothesis. How does it solve anything?
    It simply means the same questions must be asked about some other rock somewhere else.

    The only difference it makes at all, is that it removes the time constraint of the 4.5 billion year age of the Earth.
    I'm with you on this one, shifting the goal posts solves nothing. Regardless of how and where life started the fact that it did is obviously evident.

    This planet may have been seeded from elsewhere, or maybe it just developed because of the chemical and environmental conditions were just right. Maybe life spontaneously develops on any body throughout the universe that has the required chemical and environmental conditions. Or just maybe life here on Earth is the first life to develop in the universe.

    Until, when/if we find evidence of E.T life then its all just speculation.
    Last edited by cosmocrazy; 2017-Mar-12 at 01:16 PM.

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    Quote Originally Posted by cosmocrazy View Post
    I'm with you on this one, shifting the goal posts solves nothing. Regardless of how and where life started the fact that it did is obviously evident.

    This planet may have been seeded from elsewhere, or maybe it just developed because of the chemical and environmental conditions were just right. Maybe life spontaneously develops on any body throughout the universe that has the required chemical and environmental conditions. Or just maybe life here on Earth is the first life to develop in the universe.

    Until, when/if we find evidence of E.T life then its all just speculation.
    Based on the Occam's razor principle, I think the most plausible explanation for the appearance of life on Earth is the one which requires neither a special delivery of microbial spores from somewhere else in the universe, nor an enormous fluke.

    Instead, life appeared because there was a time during the Hadean period when chemical and thermodynamic conditions on Earth favoured the appearance of carbonaceous polymers, and subsequent chemical evolution towards more effective catalytic systems, including virus-like bodies and primitive cells. If so, it is reasonable to expect something comparable to happen on other worlds where chemical and thermodynamic conditions are comparable to those on Hadean period Earth.

    A couple of points worth noting:

    1. Hadean period Earth was very different from Earth today — for instance it had little or no free oxygen and lots more volcanoes. Stuff could happen then which probably can't happen on Earth today.
    2. According a recent model of the earliest stages of abiogenesis (the cyanosulfidic theory), objects from beyond Earth (e.g. comets) did play a role — not by bringing in spores or ready-made building blocks, but because their frequent impacts with Earth's atmosphere resulted in the formation of hydrogen cyanide (HCN). It is a very simple molecule, but rich in energy, chemically related to amino acids and proteins, and it polymerises easily.
    Last edited by Colin Robinson; 2017-Mar-13 at 04:54 AM.

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    Quote Originally Posted by Noclevername View Post
    Where else, and why do you think that?
    The reason why I think that is because look at how many of the elements on our planet came from "somewhere else." Metals were formed by super novae, flew all around the universe for a while, then eventually converged on the proto-planetary disk which would one day lead to Earth. I see life on Earth as possibly being analogous to this. (I'm certainly not married to the idea, and I admit is may be a bit outside the mainstream, but I think it is plausible).

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