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Colin Robinson
2012-Jun-09, 11:22 PM
Does it matter whether we think in terms of "exo-life" or "life in the universe"? Which concept is more in keeping with Copernican astronomy?

If we think in terms of "exo-life", or "extra-terrestrial life", the first question that arises is: "Does it exist?"

It is possible to compare "extra-terrestrials" with elves or mermaids: Like elves and mermaids, extra-terrestrials often appear in imaginative literature, but hard evidence of their physical existence is lacking.

On the other hand, if we think in terms of "life in universe", the question of its existence is already answered: There is life on Earth; and Earth is in the universe.

The question then is: "How common or how rare is life in the universe?"

Paul Wally
2012-Jun-09, 11:49 PM
On the other hand, if we think in terms of "life in universe", the question of its existence is already answered: There is life on Earth; and Earth is in the universe.

The question then is: "How common or how rare is life in the universe?"

I agree with this view of "life in the universe" and I think "terrestrial" and "extra-terrestrial" represents an artificial distinction in a universe that is obviously neither geocentric nor anthropocentric. From the perspective of a neutral observer, say a visitor from another galaxy, the Earth will be one instance of life in this galaxy. This neutral observer won't draw the distinction of Earth-life and Exo-life. Relative to this neutral observer all life in this galaxy will be exo-life.

R.A.F.
2012-Jun-10, 12:53 AM
It is possible to compare "extra-terrestrials" with elves or mermaids...

"If" the ET's are of the flying saucer variety, then the comparison has validity.



On the other hand, if we think in terms of "life in universe", the question of its existence is already answered: There is life on Earth; and Earth is in the universe.

The question is usually posed as "is there life elsewhere in the Universe?"...anyhow, semantically speaking, I wonder if the same thing said in different languages would have the same "pun" value.



The question then is: "How common or how rare is life in the universe?"

Well, that's an easy one...we don't know....personal opinion is that there is in fact other advanced civilizations somewhere out there, but the distances involved are so vast, I think it quite possible that we will never meet ET's.


I'd love to be proved wrong.




Oh...one other thing....




Does it matter whether we think in terms of "exo-life" or "life in the universe"? Which concept is more in keeping with Copernican astronomy?

What does one have to do with the other? How does Copernican astronomy relate to what terms are used to describe "other life"???

Selfsim
2012-Jun-10, 02:17 AM
Does it matter whether we think in terms of "exo-life" or "life in the universe"? Which concept is more in keeping with Copernican astronomy?

If we think in terms of "exo-life", or "extra-terrestrial life", the first question that arises is: "Does it exist?"

It is possible to compare "extra-terrestrials" with elves or mermaids: Like elves and mermaids, extra-terrestrials often appear in imaginative literature, but hard evidence of their physical existence is lacking.

On the other hand, if we think in terms of "life in universe", the question of its existence is already answered: There is life on Earth; and Earth is in the universe.

The question then is: "How common or how rare is life in the universe?"
The generalisation of 'life' beyond the one sample we have undeniable evidence for, is the issue I see here.
If such generalisation is supportable by physical evidence, then we might have a chance of coming up with a 'Universal' theory of life which is testable, (by physical exploration/discovery), and would then have scientific relevance.

The only ways I can see to make the leap from the one unique life model we presently have, to a generalised model, is to:

i) discover another instance of independent life emergence either on, or beyond Earth or;
ii) discover life in the lab (ie: discover how to synthesise it from scratch).

We cannot yet predict the necessary details of what we could then learn from such discoveries. If such a discovery represents a second independent emergence of life, then I would think we would be well on the way towards developing a generalised 'Universal' model, but until that happens, all that remains is pure speculation. It seems to me this needs to become much, much clearer

The Copernican Principle may still be valid at the large astronomical scales, but it is not a sufficient enough basis to extrapolate from about 'life', (ie: granular enough), as it says nothing about the diversity of what we observe around us at the smaller scales. In fact, its application at the microscopic levels is irrelevant and moot. Its like trying invoke quantum mechanical principles to explain how a planet orbits its star.

The 'commonness' or 'rareness' question you pose, is unanswerable without further discoveries and a lot more data.
Even then, a 'likely' outcome is not a dead certainty.

The presence of life on Earth does not imply life elsewhere, and the number of exo-planets discovered in the observable universe, is a moot point until another discovery is made within it.

Selfsim
2012-Jun-10, 02:37 AM
I agree with this view of "life in the universe" and I think "terrestrial" and "extra-terrestrial" represents an artificial distinction in a universe that is obviously neither geocentric nor anthropocentric. From the perspective of a neutral observer, say a visitor from another galaxy, the Earth will be one instance of life in this galaxy. This neutral observer won't draw the distinction of Earth-life and Exo-life. Relative to this neutral observer all life in this galaxy will be exo-life.Such a hypothetical 'neutral' observer would have to be something along the lines of Maxwell's demon, otherwise its own presence biases the outcome of the observation (thus not achieving 'neutrality'). How this demon would then define life, might be a perplexing question, as it itself, would be neither living nor non-living. If it was neither living nor non-living, it would be incapable of distinguishing between the two observations ... so, how would it recognise 'life' anywhere? If it couldn't recognise life anywhere, then the distinction between the terms Earth-'life' and non-Earth 'life', disappears as well.

The frame of reference from which it observes other parts of the universe, would be irrelevant.

Colin Robinson
2012-Jun-10, 03:53 AM
What does one have to do with the other? How does Copernican astronomy relate to what terms are used to describe "other life"???

A term like "extra-terrestrial" involves a conceptual separation of the Earth from the rest of the universe.

Today, thanks to Copernicus we think of the Earth as a planet comparable to other planets. And yet, many relics of pre-Copernican thinking remain in the way we talk about the universe.

For instance, the very fact that we speak of "the Earth" is based on the old idea that Earth is an object in a class of its own. We don't speak of "the Mars" or "the Jupiter".

We do speak of "the Moon" and "the Sun", but only because each of these bodies looks unique when viewed from Earth. We don't speak of "the Ganymede" or "the Sirius".

The term "extra-terrestrial" -- as in "extra-terrestrial life" -- is based on the same old idea, that Earth is in a class of its own. We might as well speak of the highlands of the Moon as "extra-terrestrial mountains", or the lakes of Titan as "exo-lakes".


Well, that's an easy one...we don't know....

I agree that we don't know how frequent or rare life is in the universe.

We know a little more than we did in the days of Kepler, when it was thought that the Moon might have life on it.


personal opinion is that there is in fact other advanced civilizations somewhere out there, but the distances involved are so vast, I think it quite possible that we will never meet ET's.

I'm inclined to think that worlds with advanced civilizations on them may be a lot less frequent than those with ecosystems of microbes. This conjecture is based on how long our own world has had micro-organisms on it, compared with how long it has had our civilization.


I'd love to be proved wrong.

If we hope to learn more than we know now, it is important that we don't jump to premature conclusions, either positive or negative.

An example of a premature negative conclusion is Senator
Richard Bryan's famous dismissal of radio SETI:

"The Great Martian Chase... may finally come to an end. As of today millions have been spent and we have yet to bag a single little green fellow."

Would you agree that cynicism like that is unhelpful to research?

Ara Pacis
2012-Jun-10, 04:26 AM
A term like "extra-terrestrial" involves a conceptual separation of the Earth from the rest of the universe. It is separate, with regards to life, as far as we can tell.


Today, thanks to Copernicus we think of the Earth as a planet comparable to other planets. And yet, many relics of pre-Copernican thinking remain in the way we talk about the universe. No we don't. It means we think of the earth as not favored or unique, not that we think that it's like everything else. That's not incompatible with the idea that the conditions for life are uncommon enough that we'll never find it elsewhere. the Copernican Principle is about how we view probability, but has no bearing on the physical reality that determines probability.


For instance, the very fact that we speak of "the Earth" is based on the old idea that Earth is an object in a class of its own. We don't speak of "the Mars" or "the Jupiter". Provincialism is provincial, and semantics is semantic. We use articles with it because earth can have different meanings in normal conversation. The moon is often referred to that way because we use the word generically instead of using a proper name for it in common conversation. you may notice that sometimes people don't capitilize earth or moon unless its used without an article.


We do speak of "the Moon" and "the Sun", but only because each of these bodies looks unique when viewed from Earth. We don't speak of "the Ganymede" or "the Sirius".On the contrary, Ganymede is "a moon" and Sirius is "a sun" for bodies in its system.


The term "extra-terrestrial" -- as in "extra-terrestrial life" -- is based on the same old idea, that Earth is in a class of its own. We might as well speak of the highlands of the Moon as "extra-terrestrial mountains", or the lakes of Titan as "exo-lakes".Geographic features are characteristics of extra-terrestrial objects, not extra-terrestrial objects on their own. One of these things is not like the others.


We know a little more than we did in the days of Kepler, when it was thought that the Moon might have life on it.IIRC, the moon does have life on it that we put there.

Selfsim
2012-Jun-10, 04:32 AM
Today, thanks to Copernicus we think of the Earth as a planet comparable to other planets. And yet, many relics of pre-Copernican thinking remain in the way we talk about the universe.This reads like an ode to Copernicus !
The modern perspective is that uniqueness, diversity and ubiquity all co-exist simultaneously, at varying scales of granularity.
The quest is to discover the scales at which each exists, doesn't exist, or co-exist.

The blanket rejection of the idea of uniqueness at arbitrary scales within the observable universe, is just as much a philosophical stance as geocentrism !

The Laws of Physics may apply regardless of one's frame of reference within the observable universe, at the same (or different) time(s), but the adoption of different values of the constants by natural processes, (in the solutions to the fundamental equations), may also occur beyond it.

Colin Robinson
2012-Jun-10, 05:11 AM
The generalisation of 'life' beyond the one sample we have undeniable evidence for, is the issue I see here.

I agree that we should be careful about generalizing from a single example.

But how many examples do we know, of planets which are habitable, and yet do not have life?

The closest thing we have to such a case (habitable yet lifeless) is Mars... except that we don't yet have undeniable evidence either for its habitability or for the absence of life there....


The presence of life on Earth does not imply life elsewhere,

Conversely, if it is confirmed that Mars has no life on it...

would the absence of life on Mars imply absence of life elsewhere?

If we were to draw sweeping conclusions from a lifeless Mars, wouldn't we be generalizing from a sample size of one?

Colin Robinson
2012-Jun-10, 07:25 AM
It is separate, with regards to life, as far as we can tell.

Perhaps that depends on what you mean by "as far as we can tell". I would agree that as yet we have no conclusive direct evidence of life on other worlds.

Please consider another class of things we have no conclusive direct evidence for yet -- exomoons, i.e. natural satellites of planets in other solar systems.

Would you say that our own solar system is in a separate category, with regard to moons, as far as we can tell?


On the contrary, Ganymede is "a moon" and Sirius is "a sun" for bodies in its system.

True. Nonetheless, when we speak of "the Moon" we don't usually mean Ganymede, and when we speak of "the Sun", we don't usually mean Sirius.

Selfsim
2012-Jun-10, 07:53 AM
I agree that we should be careful about generalizing from a single example.

But how many examples do we know, of planets which are habitable, and yet do not have life?

The closest thing we have to such a case (habitable yet lifeless) is Mars... except that we don't yet have undeniable evidence either for its habitability or for the absence of life there....If the test for a generalised hypothesis returns null or positive results .. then progress can be made.

If the test returns no result, then the test should be revised, or change the hypothesis.

That the test results might be hard to obtain, is of no concern to theoretical science.

If one seeks to establish a physical theory, one needs real-world results, consistent with that theory.

Marching on, assuming that a mapping between theory and the real world exists, is delusional.




The presence of life on Earth does not imply life elsewhereConversely, if it is confirmed that Mars has no life on it... would the absence of life on Mars imply absence of life elsewhere?No.

If we were to draw sweeping conclusions from a lifeless Mars, wouldn't we be generalizing from a sample size of one?Yes.

What's your point here, Colin ?

Colin Robinson
2012-Jun-10, 09:24 AM
What's your point here, Colin ?

My point is that there is more than one kind of speculation.

Please consider the following propositions:

1.Out of the total number of habitable worlds in the universe, the majority have some form of life on them.
2.Out of the total number of habitable worlds in the universe, the majority are without life.

Presumably one or other of these is true. (Unless the proportion of habitable worlds with life is exactly 50 percent...)

I'd agree with you that proposition 1 is not proven. Although we do have one example of a habitable world with life on it, namely Earth, that does not prove proposition 1. To prove it (as you've pointed out) we would either need a very thorough understanding of abiogenesis, or else we would need to find other habitable worlds and identify organisms on them.

On the other hand, proposition 2 is not proven either. We don't yet even have one confirmed example of a habitable world without life on it. Mars may turn out to be an example of this, but we don't actually know that yet. Even if Mars does turn out to be both habitable and lifeless, it will still be one example only. We would then need a larger sample of habitable worlds to determine whether Earth or Mars is more typical. Or else we would need a thorough understanding of abiogenesis, and why it is a low-probability event.

Selfsim
2012-Jun-10, 12:09 PM
My point is that there is more than one kind of speculation.

Please consider the following propositions:

1.Out of the total number of habitable worlds in the universe, the majority have some form of life on them.
2.Out of the total number of habitable worlds in the universe, the majority are without life.

Presumably one or other of these is true. (Unless the proportion of habitable worlds with life is exactly 50 percent...)
Well, no.
Assuming 'the universe' refers to the 'observable universe' (only), the following statement is present-day physical fact ... ('truth' has nothing to do with it):
3. Out of the total number of habitable worlds in the universe, we know of extant life on one planet only.

I really dislike the term 'habitable worlds', but for the sake of harmony .. I'll ride along with it ... for the moment. ;)
We should also discount any lifeforms sent along on our probes, etc, also.

Statements #1 and #2 are not practically verifiable or falsifiable, because it is not feasible to travel to the necessary number of 'habitable worlds', in order to apply the necessary tests, and retrieve the results, (distances being the main limiting factor).

If 'the universe' is theoretically infinite, (in time, and spatially), then in theory:
4. There would be an infinite number of life instances throughout the universe, including exact duplicates of Earth-life, in every detail.
The problem here of course, is that it in practice, it is also not feasible to test this statement. I doubt that it would be theoretically feasible either, although there is a theoretical/philosophical argument called 'Infinite Tasking', which might just sneak it over the line, as far as theoretical testability is concerned.


I'd agree with you that proposition 1 is not proven. Although we do have one example of a habitable world with life on it, namely Earth, that does not prove proposition 1. To prove it (as you've pointed out) we would either need a very thorough understanding of abiogenesis, or else we would need to find other habitable worlds and identify organisms on them.

On the other hand, proposition 2 is not proven either. We don't yet even have one confirmed example of a habitable world without life on it. Mars may turn out to be an example of this, but we don't actually know that yet. Even if Mars does turn out to be both habitable and lifeless, it will still be one example only. We would then need a larger sample of habitable worlds to determine whether Earth or Mars is more typical. Or else we would need a thorough understanding of abiogenesis, and why it is a low-probability event.'Proofs' exist in mathematics ... and Courts of Law .. I'm not aware of such in physics. Verification/falsification of the 'majority' term, would involve testing the necessary number of 'habitable worlds' within the finite set, within the observable universe .. which is not practically feasible.
If we gain knowledge of biological, environmental causative and inhibitive factors from discoveries, and this knowledge then goes into an abiogenesis theory, then probablisitic estimates might gain some evidence-based credibility.

Regards

R.A.F.
2012-Jun-10, 12:54 PM
My point is that there is more than one kind of speculation.

Well, evidenced speculation isn't speculation anymore, so there is only one "type", that being unevidenced speculation.

Paul Wally
2012-Jun-10, 02:55 PM
Such a hypothetical 'neutral' observer would have to be something along the lines of Maxwell's demon, otherwise its own presence biases the outcome of the observation (thus not achieving 'neutrality'). How this demon would then define life, might be a perplexing question, as it itself, would be neither living nor non-living. If it was neither living nor non-living, it would be incapable of distinguishing between the two observations ... so, how would it recognise 'life' anywhere? If it couldn't recognise life anywhere, then the distinction between the terms Earth-'life' and non-Earth 'life', disappears as well.


What you are saying implies that there are no neutrally observable differences between living and non-living systems, which is absurd.



If one seeks to establish a physical theory, one needs real-world results, consistent with that theory.


Yes that's right, consistent with, but this theory must also have implications that might possibly be inconsistent with future real-world results.


Marching on, assuming that a mapping between theory and the real world exists, is delusional.

The whole point of testing a theory is to check the "mapping between theory and real world", so complete mapping is never assumed. But a theory must have implications beyond the available evidence, otherwise it is really completely useless as a scientific theory.





If 'the universe' is theoretically infinite, (in time, and spatially), then in theory:
4. There would be an infinite number of life instances throughout the universe, including exact duplicates of Earth-life, in every detail.
The problem here of course, is that it in practice, it is also not feasible to test this statement. I doubt that it would be theoretically feasible either, although there is a theoretical/philosophical argument called 'Infinite Tasking', which might just sneak it over the line, as far as theoretical testability is concerned.



We have a much stronger theoretical base of scientific discoveries in physics, chemistry, geology etc. to work from than the empty "in theory" scenario you're sketching above. What is needed is an explanation of how life emerges in a universe working according to laws we have discovered until now. Once we have such an explanation then that explanation can be tested against the evidence.



Well, evidenced speculation isn't speculation anymore, so there is only one "type", that being unevidenced speculation.

Well, in a scientific context, it's called "conjecture" and it's purpose is usually to explain something.

Colin Robinson
2012-Jun-10, 11:21 PM
Out of the total number of habitable worlds in the universe, we know of extant life on one planet only.

Out of the total number of habitable worlds in the universe, we have tested for extant life on two planets only.

What we know is limited. The question is, how can we know more?


I really dislike the term 'habitable worlds',

Why do you dislike the term "habitable worlds"?


We should also discount any lifeforms sent along on our probes, etc, also.

Agreed. Claimed survival of earth microbes on devices sent to the Moon doesn't tell us much about how common or rare life is in the universe. Except that it makes the idea of spacecraft-assisted panspermia seem a little more feasible.


If we gain knowledge of biological, environmental causative and inhibitive factors from discoveries, and this knowledge then goes into an abiogenesis theory, then probablisitic estimates might gain some evidence-based credibility.

I agree that greater understanding of abiogenesis would help us to estimate how many worlds abiogenesis has happened on.

Regards
Colin

Ara Pacis
2012-Jun-10, 11:21 PM
Perhaps that depends on what you mean by "as far as we can tell". I would agree that as yet we have no conclusive direct evidence of life on other worlds.As far as we can tell we can't rule out pre-historic cross-contamination in our own solar system, so even if we find life elsewhere in this solar system, we may not be able to show that it came from a separate abiogenesis event.


Please consider another class of things we have no conclusive direct evidence for yet -- exomoons, i.e. natural satellites of planets in other solar systems.

Would you say that our own solar system is in a separate category, with regard to moons, as far as we can tell?There is no such thing as an exo-moon. Moons cannot be described as exo because moons cannot be exo. A moon, by definition, is always subject to identification with a planet. A planet may be exo, and thus an exo-planet may have a moon, but no planet, local or exo, can have an exo-moon because at that point it is no longer a moon.


True. Nonetheless, when we speak of "the Moon" we don't usually mean Ganymede, and when we speak of "the Sun", we don't usually mean Sirius.If we lived on Jupiter, we might, if we chose to ignore all the other moons. If we lived in the Sirian system we almost certainly would. A frame of reference is a reference for framing.

Selfsim
2012-Jun-11, 12:08 AM
I agree with this view of "life in the universe" and I think "terrestrial" and "extra-terrestrial" represents an artificial distinction in a universe that is obviously neither geocentric nor anthropocentric. From the perspective of a neutral observer, say a visitor from another galaxy, the Earth will be one instance of life in this galaxy. This neutral observer won't draw the distinction of Earth-life and Exo-life. Relative to this neutral observer all life in this galaxy will be exo-life.
Such a hypothetical 'neutral' observer would have to be something along the lines of Maxwell's demon, otherwise its own presence biases the outcome of the observation (thus not achieving 'neutrality'). How this demon would then define life, might be a perplexing question, as it itself, would be neither living nor non-living. If it was neither living nor non-living, it would be incapable of distinguishing between the two observations ... so, how would it recognise 'life' anywhere? If it couldn't recognise life anywhere, then the distinction between the terms Earth-'life' and non-Earth 'life', disappears as well.What you are saying implies that there are no neutrally observable differences between living and non-living systems, which is absurd.No more absurd than your hypothetical 'neutral' alien observer.
How can an alien observer possibly be 'neutral' in this case ?


If one seeks to establish a physical theory, one needs real-world results, consistent with that theory.Yes that's right, consistent with, but this theory must also have implications that might possibly be inconsistent with future real-world results.Why must it ?
How would anyone possibly know, in the present-day, about any 'future real-world inconsistencies', such that they would form part of a present-day 'theory', for an as yet unobserved phenomenon?


The whole point of testing a theory is to check the "mapping between theory and real world", so complete mapping is never assumed. But a theory must have implications beyond the available evidence, otherwise it is really completely useless as a scientific theory.Well, we're starting to make progress … finally ! (Only in as far as your scoping of what abiogenesis is to be used for, (ie: prediction), from your own perspective).

Evolutionary molecular biological research is far from being 'completely useless'. Its interpretation within the context of predictions of abiogenesis elsewhere, cannot realise value in science until it has evidence in direct support of a second emergence .. and for all the other reasons cited in the other thread. (http://www.bautforum.com/showthread.php/133485-Is-Life-Inevitable)


We have a much stronger theoretical base of scientific discoveries in physics, chemistry, geology etc. to work from than the empty "in theory" scenario you're sketching above. What is needed is an explanation of how life emerges in a universe working according to laws we have discovered until now. Once we have such an explanation then that explanation can be tested against the evidence.Why is this needed ? If there is a purpose, then philosophical determinism is the driver.
Its becoming much clearer that this 'theory' is really a speculative hypothesis bounded by known Physics (which I don't have a problem with) … it is not a scientific theory, because it cannot predict specifically emergence, as it has no basis in empiricism until a second emergence is either synthesised in the lab or discovered someplace.

I am concluding that the "must" term you keep citing, is evidence of a desire, driven by a philosophical belief, that the universe and life emergence, be fundamentally determinable .. which is falsified in general, by many physical examples so far cited in other threads.


Well, in a scientific context, it's called "conjecture" and it's purpose is usually to explain something.I'm not sure what definitions of scientific Theory and Hypothesis you're drawing from, but as a first blush, mine are (roughly):

Hypothesis: A tentative statement such as ‘if A happens then B must happen’ that can be tested by direct experiment or observation. A repeatedly verified hypothesis can be expressed as a law or a theory. A disproven hypothesis can sometimes be re-tested and found to be subsequently verified, as measurements improve.

Theory: An explanation for why/how certain laws and facts exist, that can be tested to determine its accuracy. It takes only one negative example to disprove a theory and one can't examine all examples of a phenomenon throughout all time and space, (the problem of induction). Theories are used to make predictions.

The highlighted and underlined parts of the above distinguish for me, what you're describing is actually a hypothesis, (a speculative one at that), which doesn't predict, due to a lack of description of directly applicable, relevant laws and fact, (in this case specific to life emergence). Inferences drawn from other areas of science do not inevitably form a solid basis for prediction in complex systems, such as life, or complex biochemical pathways.

I offer this as a possible way to describe where I'm coming from .. not as a way to promote argument. If my definition is not agreed, then at least we'll understand why we aren't seeing eye-to-eye on this.

Regards

Colin Robinson
2012-Jun-11, 12:16 AM
There is no such thing as an exo-moon. Moons cannot be described as exo because moons cannot be exo. A moon, by definition, is always subject to identification with a planet. A planet may be exo, and thus an exo-planet may have a moon, but no planet, local or exo, can have an exo-moon because at that point it is no longer a moon.

You are thinking of what is called a rogue planet (http://en.wikipedia.org/wiki/Rogue_planet). The term exoplanet (http://en.wikipedia.org/wiki/exoplanet) simply means a planet outside our own solar system. "Extrasolar planet" is a more longwinded synonym. If an exoplanet has a moon, it is termed an exomoon (http://en.wikipedia.org/wiki/exomoon), or extrasolar moon.

Why did I mention extrasolar moons? Simply because:

1.We have zero direct evidence that they exist.
2.There are cogent indirect reasons for thinking that they would exist.
3.Looking for direct evidence is considered valid scientific work.
4.If they do exist, they will not be a basically new class of thing, rather members of an existing class of thing (moons), but in different and more remote locations.

All of which, as far as I can see, also applies to life beyond Earth.

Selfsim
2012-Jun-11, 12:27 AM
Out of the total number of habitable worlds in the universe, we have tested for extant life on two planets only.

What we know is limited. The question is, how can we know more?Fair enough .. agreed.
Exploration and direct testing is one way to know more.


Why do you dislike the term "habitable worlds"?My definition, (including online dictionary definitions), of 'world' is:
"The Earth, (or planet in this case), together with its countries, peoples, societies, institutions, lifeforms and natural features."

In this case those other 'worlds' are more accurately termed as 'planets'.



If we gain knowledge of biological, environmental causative and inhibitive factors from discoveries, and this knowledge then goes into an abiogenesis theory, then probablisitic estimates might gain some evidence-based credibility.I agree that greater understanding of abiogenesis would help us to estimate how many worlds abiogenesis has happened on.I stand by my words above, (not necessarily what you said above). I'd prefer to change the exact wording by removing 'theory' and inserting 'hypothesis'. I also further qualified this perspective in my other statement with words to the effect of:
"Even a 'likely' outcome, is not a dead certainty".

Regards

Colin Robinson
2012-Jun-11, 12:37 AM
In this case those other 'worlds' are more accurately termed as 'planets'.

I see... The reason I use the term "habitable worlds", is that I mean to include habitable moons, as well as habitable planets.

Selfsim
2012-Jun-11, 02:12 AM
I see... The reason I use the term "habitable worlds", is that I mean to include habitable moons, as well as habitable planets.The language lets us down a bit, eh ?

.. perhaps a 'planety moony thingy' ? :)

Cheers

Selfsim
2012-Jun-11, 03:07 AM
Why did I mention extrasolar moons? Simply because:

1.We have zero direct evidence that they exist.
2.There are cogent indirect reasons for thinking that they would exist.
3.Looking for direct evidence is considered valid scientific work.
4.If they do exist, they will not be a basically new class of thing, rather members of an existing class of thing (moons), but in different and more remote locations.

All of which, as far as I can see, also applies to life beyond Earth.So now, 'Wally's Neutral Demon' (analogous with 'Maxwell's demon') .. is defined as being incapable of distinguishing between 'life' and a 'moon', eh (??)

:) (Just kidding).

Cheers

Ara Pacis
2012-Jun-11, 04:53 AM
You are thinking of what is called a rogue planet (http://en.wikipedia.org/wiki/Rogue_planet).No, I'm not.


If an exoplanet has a moon, it is termed an exomoon (http://en.wikipedia.org/wiki/exomoon), or extrasolar moon.According to who? Did I miss an IAU vote?

I was attempting to show the absurdity of the term, but apparently other people have absurd notions about semantics. Anyways, until there is an official definition, I'll use mine.


Why did I mention extrasolar moons? Simply because:

1.We have zero direct evidence that they exist.
2.There are cogent indirect reasons for thinking that they would exist.
3.Looking for direct evidence is considered valid scientific work.
4.If they do exist, they will not be a basically new class of thing, rather members of an existing class of thing (moons), but in different and more remote locations.

All of which, as far as I can see, also applies to life beyond Earth.You're making a classic mistake. You're confusing category for population.

Colin Robinson
2012-Jun-11, 05:27 AM
So now, 'Wally's Neutral Demon' (analogous with 'Maxwell's demon') .. is defined as being incapable of distinguishing between 'life' and a 'moon', eh (??)

:) (Just kidding).

Cheers

Seriously, Selfsim, I don't see what you find so ridiculous about Paul's concept of a neutral observer.

This is what Paul originally wrote:


I agree with this view of "life in the universe" and I think "terrestrial" and "extra-terrestrial" represents an artificial distinction in a universe that is obviously neither geocentric nor anthropocentric. From the perspective of a neutral observer, say a visitor from another galaxy, the Earth will be one instance of life in this galaxy. This neutral observer won't draw the distinction of Earth-life and Exo-life. Relative to this neutral observer all life in this galaxy will be exo-life.

Surely, it is clear (in this context) that a "neutral observer" means someone who observes things in this galaxy without beginning with the assumption that one particular planet or solar system is in a different category from all the rest?

We earthlings have actually been working towards this sort of conceptual neutrality for the past few centuries. It is what the Copernican revolution in astronomy is all about.

Why would a neutral observer use a term like "exomoons" for any moons of any solar systems except one? Would it not be more consistent with neutrality to speak of "moons of the Milky Way Galaxy"?

Why would a neutral observer use a different term like "exolife" for any living things on any planet except one? Would it not be more consistent with neutrality to speak of "life in the Milky Way Galaxy"?

Colin Robinson
2012-Jun-11, 05:54 AM
If an exoplanet has a moon, it is termed an exomoon, or extrasolar moon.
According to who?

According to, for instance, the astronomers engaged in the Hunt for Exomoons with Kepler project (HEK) (http://arxiv.org/abs/1201.0752).


I was attempting to show the absurdity of the term, but apparently other people have absurd notions about semantics.

I actually find the term "exomoon" somewhat absurd too. But no more absurd than the term "exolife"…


You're making a classic mistake. You're confusing category for population.

According to which classical authority is that a classic mistake? How is the mistake defined, and why do you think I am making it?

Selfsim
2012-Jun-11, 06:55 AM
Seriously, Selfsim, I don't see what you find so ridiculous about Paul's concept of a neutral observer.
.. {snip} ...
We earthlings have actually been working towards this sort of conceptual neutrality for the past few centuries. It is what the Copernican revolution in astronomy is all about.If you want to get serious about it, then I would recommend dropping the semantic games immediately.

The point is that the Copernican Principle has only loosely and scantily, indirectly inferred applicability only, when it comes to distinguishing 'Earth life'/'exo-life', 'terrestrial life'/'extra-terrestrial life', (or whatever hypothetical semantic flavour one chooses) at biological scale levels. As a matter of fact, the observer cannot escape the bias introduced by noticing the nature of its own existence (biology), in a universe where no other comparative life-forms have been observed. 'Neutrality' when it comes to observing a one-life model observable universe, is meaningless.

If the so-called neutral observer has developed knowledge of a universal model of life, courtesy of an astronomical amount of prior testing, then this would be the testing basis for distinguishing differences ... not a philosophical posit about the ubiquity of physical laws and environments throughout an observable universe.

Colin Robinson
2012-Jun-11, 08:15 AM
If you want to get serious about it, then I would recommend dropping the semantic games immediately.

Not quite sure what you mean by "semantic games"...

The topic I raised in the opening post of this thread was the difference between thinking in terms of "exo-life" or "life in the universe"... Are you saying that this whole topic is just a semantic game?


As a matter of fact, the observer cannot escape the bias introduced by noticing the nature of its own existence (biology), in a universe where no other comparative life-forms have been observed. 'Neutrality' when it comes to observing a one-life model observable universe, is meaningless.

It's true that no other life-forms have been observed by us terrestrials. Does that mean we are in a "one-life model observable universe"? Are "observed" and "observable" the same thing?

Has everything observable on the surface of Mars (for instance) already been observed? If so, why do we bother to send new devices there, such as the Curiosity rover?

Paul Wally
2012-Jun-11, 01:43 PM
How can an alien observer possibly be 'neutral' in this case ?


Maybe because I defined it as neutral. But your argument implies that neutrality is impossible, and that's why I'm asking, how can the distinction between living and non-living not be a neutral observation, i.e. how can life not be objectively recognizable as life? Is life relative? That would make the fact that we are alive relative too, which is absurd.


Why must it ?
How would anyone possibly know, in the present-day, about any 'future real-world inconsistencies', such that they would form part of a present-day 'theory', for an as yet unobserved phenomenon?

A theory must have implications beyond the evidence, otherwise it's completely useless as a theory. Now these implications might be inconsistent with future real-world discoveries. Scientific theories are not infallible.



Evolutionary molecular biological research is far from being 'completely useless'. Its interpretation within the context of predictions of abiogenesis elsewhere, cannot realise value in science until it has evidence in direct support of a second emergence .. and for all the other reasons cited in the other thread. (http://www.bautforum.com/showthread.php/133485-Is-Life-Inevitable)

I'm not referring to "evolutionary molecular biological research". I'm saying that anything that doesn't make predictions beyond current evidence is completely useless as a scientific theory. It shouldn't even be called a scientific theory. The Ptolemaic system of the solar system is an example of a theory that's incapable of making novel predictions and it's not even wrong, as Wolfgang Pauli would say. The research program that you're proposing implies that we cannot proceed theoretically unless we have evidence of a second instance of life, but if we cannot proceed theoretically with one instance there's no guarantee that a second instance is going to bring us any closer to solving the problem of abiogenesis. There's no guarantee that an n-th instance is going to solve the problem. That is because the problem is theoretical, that is, to explain how abiogenesis is possible in this universe.



Why is this needed ? If there is a purpose, then philosophical determinism is the driver.

The purpose is understanding, and in order to understand something we need to explain it.


Its becoming much clearer that this 'theory' is really a speculative hypothesis bounded by known Physics (which I don't have a problem with) … it is not a scientific theory, because it cannot predict specifically emergence, as it has no basis in empiricism until a second emergence is either synthesised in the lab or discovered someplace.

The theory I'm referring to, which explains abiogenesis from established empirically based scientific theories, doesn't exist yet. Since it doesn't exist yet, you cannot know beforehand what it will be capable of predicting.


I am concluding that the "must" term you keep citing, is evidence of a desire, driven by a philosophical belief, that the universe and life emergence, be fundamentally determinable .. which is falsified in general, by many physical examples so far cited in other threads.

"Fundamentally determinable" is a bit vague, therefore it is not at all clear what it is that is falsified, according to you. I proceed on the premise that the universe and life emergence is intelligible , but that's not the same as deterministic.



I'm not sure what definitions of scientific Theory and Hypothesis you're drawing from, but as a first blush, mine are (roughly):

Hypothesis: A tentative statement such as ‘if A happens then B must happen’ that can be tested by direct experiment or observation. A repeatedly verified hypothesis can be expressed as a law or a theory. A disproven hypothesis can sometimes be re-tested and found to be subsequently verified, as measurements improve.

In the definitions I've seen, the hypothesis is the antecedent of the conditional statement (if A then B), where only A is the hypothesis and B is that which requires explanation.
See the Wikipedia article on hypothesis (http://en.wikipedia.org/wiki/Hypothesis): "A hypothesis (from Greek ὑπόθεσις; plural hypotheses) is a proposed explanation for a phenomenon."



Inferences drawn from other areas of science do not inevitably form a solid basis for prediction in complex systems, such as life, or complex biochemical pathways.

As I repeatedly tried to make clear: Complexity is a mathematically implicit possibility, and therefore it can follow implicitly from a system defined purely on the basis of physical and chemical laws. These have been computationally demonstrated. The point is that you don't know that these "other areas of science", combined with purely mathematical complexity theory, are insufficient for the development of a theory of abiogenesis capable of making testable predictions.



I offer this as a possible way to describe where I'm coming from .. not as a way to promote argument. If my definition is not agreed, then at least we'll understand why we aren't seeing eye-to-eye on this.

Yes, your definition of hypothesis is not agreed upon. It appears to limit hypothesis to mere mechanical inductive generalization; something a computer can be taught to do. You assume that evidence leads like breadcrumbs to a comprehensive theory of phenomena. Inductive generalization leaves hardly any room for human creativity, conceptual inventiveness and originality.

Ara Pacis
2012-Jun-11, 07:38 PM
According to, for instance, the astronomers engaged in the Hunt for Exomoons with Kepler project (HEK) (http://arxiv.org/abs/1201.0752). Doesn't make them an authority on nomenclature.


I actually find the term "exomoon" somewhat absurd too. But no more absurd than the term "exolife"…Then don't use it. You have agency in what you do and what you say. I'm not a fan of the term exolife either, but it does have a different basis and description. A moon is a class of object, and is itself meaningless without a plant about which it orbits. A more proper formulation would be exoplanet moon because exo is not useful for defining the object moon due to the different degrees of separation in concept. I wouldn't be so hardcore about this, except the IAU has bent over backwards to make a ridiculous definition of "planet" such that we can't actually know if any object we detect in another system can be considered a planet (ignoring the fact that it doesn't orbit our sun). Some asteroids have objects orbiting them, we don't call those asteroid-moons, we just call them moons, or more properly, satellites.


According to which classical authority is that a classic mistake? How is the mistake defined, and why do you think I am making it?Group Dynamics Theory, for one. Have you no conception in the english language that you cannot determine the difference in meaning yourself? A group or population are part of a single system through interaction: it's a physical organization. A category or collection is based only on similar traits: it's a logical organization. For example, The student body of a college is a group, because they all interact in some manner. However, "freshmen of colleges across the country" is a category, since they do not interact as part of a unitary system.

Life is a system. Life, so far as we can tell, starts and continues and in a manner of thinking is, what I'll call, a hyper-organism with a continuous existence going back billions of years perhaps to a single origin. Life on Mars might be part of that hyper-organism but we don't know if there is life or if it is part of the same genesis because we have reason to believe that dispersal is plausible within our solar system. Life anywhere else in the universe is likely to not be related unless and until a link can be established. Thus, exo has some sort of distinction between us and them. However, balls of matter with certain arbitrary definitions scattered throughout the observable universe is exactly that, unrelated blobs of matter that merely present similar characteristics to a definition.

Selfsim
2012-Jun-11, 09:14 PM
Not quite sure what you mean by "semantic games"...

The topic I raised in the opening post of this thread was the difference between thinking in terms of "exo-life" or "life in the universe"... Are you saying that this whole topic is just a semantic game? Frankly, the OP struck me as announcing a seemingly deliberate attempt to skirt around the major elephant in the room, which is that other instances of emerged life, are not simply 'a given'. The word-play even announces to the reader that the whole issue of exo-life existence can be avoided by selective use of language labels. I call that semantics .. pure and simple.

Your OP reference to the Copernican Principle, also sounds the warning bells and a 'call-to-arms' to all casually interested amateur astronomers that a key principle of Cosmology is threatened if Earth-life is inferred to not be ubiquitously distributed. I call this game-play.


It's true that no other life-forms have been observed by us terrestrials. Does that mean we are in a "one-life model observable universe"? Who knows ?? Who can I consult with, who knows the 'truth' of this matter ? Paul Wally's 'Neutral' Demon, who is so far incapable of distinguishing life from non-life, and life from moons ?

Are "observed" and "observable" the same thing? Once again ... same answer .. when it comes to life ... who knows ?


Has everything observable on the surface of Mars (for instance) already been observed? If so, why do we bother to send new devices there, such as the Curiosity rover?Has everything observable on the surface of Earth already been observed ?
No way ! The latest predicted estimate of the number of eukaryote species on Earth is ~8.74 million, and only 1.94 million, (22%), have been described/catalogued to date ... all that after 3.2 to 4.4 million years of human evolutionary existence !
With that information, I'd say the above questions are indicative of yet more moot thinking, carrying no meaning.

In fact, an even bigger number of Earth-life species, all share the same life model ... with none displaying evidence of even one single, separate instance of independent emergence. I'd say that's some pretty good evidence that the emergence and subsequent evolution process, is pretty selective ... in spite of the attempted philosophically motivated co-option of the Copernican Principle into the life topic !

Colin Robinson
2012-Jun-11, 09:55 PM
Then don't use it. You have agency in what you do and what you say.

Yes. But if I invent new words, or give existing words new meanings, I may diminish the chance that others will understand what I say. "Exomoon" is a term in current usage in the scientific community, and that is why I've used it, even though I find it conceptually problematic.


I'm not a fan of the term exolife either

Why are you not a fan of the term "exolife"?


A group or population are part of a single system through interaction: it's a physical organization. A category or collection is based only on similar traits: it's a logical organization. For example, The student body of a college is a group, because they all interact in some manner. However, "freshmen of colleges across the country" is a category, since they do not interact as part of a unitary system.

Life is a system. Life, so far as we can tell, starts and continues and in a manner of thinking is, what I'll call, a hyper-organism with a continuous existence going back billions of years perhaps to a single origin. Life on Mars might be part of that hyper-organism but we don't know if there is life or if it is part of the same genesis because we have reason to believe that dispersal is plausible within our solar system. Life anywhere else in the universe is likely to not be related unless and until a link can be established. Thus, exo has some sort of distinction between us and them.

OK, life on Earth is a system, a population, perhaps a hyperorganism. Life on other worlds (especially worlds in other solar systems) would presumably not be part of the same population. I agree with you about all of this.

Nonetheless, life on other worlds would logically have to possess characteristics in common with life on Earth, as otherwise it would make no sense to call it "life" at all. So the term "life in the universe" makes sense as a category. Life on Earth is a population within that category.


However, balls of matter with certain arbitrary definitions scattered throughout the observable universe is exactly that, unrelated blobs of matter that merely present similar characteristics to a definition.

The balls of matter within this solar system -- the planets and moons -- do interact gravitationally, and have a presumed common origin in an ancient cloud of dust and gases. Why can't they, too, be considered a "population" or "group"?

If the term "exolife" is defensible on the grounds that Earth life is a population, while exolife would be outside that population, can't the terms "exoplanet" and "exomoon" be defended on analogous grounds --that the planets and moons of the solar system are a dynamically interacting group, whereas exoplanets and exomoons are outside that group?

Colin Robinson
2012-Jun-11, 11:25 PM
Frankly, the OP struck me as announcing a seemingly deliberate attempt to skirt around the major elephant in the room, which is that other instances of emerged life, are not simply 'a given'.

"Exolife", if it exists, is not an elephant in the room.

More a case of an elephant light-years away -- observable in principle, but actually observing one will take considerable effort.

Life on Earth is more like an elephant in the room -- why talk about it, we all know it is there?

But it should at least convince us that elephants do exist...


In fact, an even bigger number of Earth-life species, all share the same life model ... with none displaying evidence of even one single, separate instance of independent emergence.

Similarities between species of life on Earth are consistent with the hypothesis that abiogenesis occurred here exactly once. (It is consistent with several other hypotheses also, but the hypothesis that abiogenesis occurred exactly once is the most economical.) If this hypothesis is right, what conclusions follow about life elsewhere?

Either Earth is a typical case of a habitable planet or it isn't.

If Earth is a typical case, and if abiogenesis has occurred once on Earth, then it will have occurred once on each other typical habitable planet.

If Earth is not a typical case, then the presumed fact that abiogenesis has occurred once on Earth tells us nothing at all about whether abiogenesis on habitable planets is frequent or rare.

Ara Pacis
2012-Jun-12, 06:13 AM
Yes. But if I invent new words, or give existing words new meanings, I may diminish the chance that others will understand what I say. "Exomoon" is a term in current usage in the scientific community, and that is why I've used it, even though I find it conceptually problematic.If they jump off a bridge, will you too?


Why are you not a fan of the term "exolife"?It goes back to the whole definition of a planet debate. I don't want to use similar terminology for populations and categories because that causes the types of conflations I mentioned earlier in the thread.


OK, life on Earth is a system, a population, perhaps a hyperorganism. Life on other worlds (especially worlds in other solar systems) would presumably not be part of the same population. I agree with you about all of this.

Nonetheless, life on other worlds would logically have to possess characteristics in common with life on Earth, as otherwise it would make no sense to call it "life" at all. So the term "life in the universe" makes sense as a category. Life on Earth is a population within that category.That's premature. At present, life in the universe is identical to life on earth because it is the only category, so there is no need to differentiate.


The balls of matter within this solar system -- the planets and moons -- do interact gravitationally, and have a presumed common origin in an ancient cloud of dust and gases. Why can't they, too, be considered a "population" or "group"?

If the term "exolife" is defensible on the grounds that Earth life is a population, while exolife would be outside that population, can't the terms "exoplanet" and "exomoon" be defended on analogous grounds --that the planets and moons of the solar system are a dynamically interacting group, whereas exoplanets and exomoons are outside that group?Depends on the astronomer. but that misses the point, if you were really comparing apples to apples then exolife would not be analogous to exomoon or exoplanet but to exosolarsystem. Planet is not a system, it's a category, so comparing it to life is apples and oranges.

Colin Robinson
2012-Jun-12, 12:33 PM
Depends on the astronomer. but that misses the point, if you were really comparing apples to apples then exolife would not be analogous to exomoon or exoplanet but to exosolarsystem. Planet is not a system, it's a category, so comparing it to life is apples and oranges.

It's just occurred to me that, in all these terms, the prefix "exo" means "remote from us". An apple or orange a few light-years away would presumably be called an "exo-apple" or "exo-orange"…

Paul Wally
2012-Jun-12, 01:01 PM
That's premature. At present, life in the universe is identical to life on earth because it is the only category, so there is no need to differentiate.



Life in the universe, or simply 'life', is a universal. Life on Earth would then be a particular instance of the universal life. A universal has many particular instances, and although the particular instances are differentiated among themselves, they share similarities which make them instances of the same universal. So "life in the universe" is not identical to "life on Earth", simply because a universal cannot be identical to a particular. Even if "life on Earth" is the only instance of "life in the universe", it doesn't make sense to say that they are identical. It would be like saying, one particular apple is identical to the concept of "apple".

The question is then what is the concept of life i.e., the universal of life? Now this universal is something that we can define. So when we define life, we then have a universal called life. There would then be a whole space of possible instances satisfying our definition, our criteria so to speak. The question of the existence of other life is then a question of whether some of the other instances of our concept of life exist in actuality. They may or may not exist in actuality, but they are still logically possible instances of the universal life.

Selfsim
2012-Jun-12, 09:35 PM
Maybe because I defined it as neutral. But your argument implies that neutrality is impossible, and that's why I'm asking, how can the distinction between living and non-living not be a neutral observation, i.e. how can life not be objectively recognizable as life? Is life relative? That would make the fact that we are alive relative too, which is absurd. Why is it absurd ?
Without sentience, could a rock distinguish life from non-life ? Sentience is an emergent property of life, and it is a fundamental for distinguishing itself.
Gee, there are some things on Earth which cannot be clearly distinguished as 'life' also (viruses, etc) … is this 'absurd', too ?

And I am led to an understanding (by the proposers of Abiogenesis 'theories'), that the reference model for 'life' is 'Earth-life', (and that the exploration of the obs. universe, will lead to enmasse testing to see if that model can then be generalised into a universal theory of life). This, out of sheer necessity, makes it relative to ourselves, which you call 'absurd'.


A theory must have implications beyond the evidence, otherwise it's completely useless as a theory. Now these implications might be inconsistent with future real-world discoveries. Scientific theories are not infallible. A hypothesis must be capable of making testable, speculative conclusions. Once these conclusions are confirmed, it might be regarded as a theory. In this particular case, at best, it is the track record of successful testable conclusions, which would generate the distinction of the theory's ability to predict.

'The existence of life on Earth, implies life elsewhere', has no basis in direct evidence. It is not a theory. It is a speculative, philosophically based hypothesis, at best.

If your 'theory' of life/abiogenesis has no track record of making successful, testable predictions of life elsewhere, then so be it .. it is useless as a theory for predicting exo-life!

As a hypothesis however .. that's different. It may be capable of making testable speculative conclusions .. so we should get on with making and testing them.

Abiogenesis within the field of Evolutionary Molecular Biology (EMB), has tremendous value.
It is the way in which a piece of research is applied, which makes all the difference .. and the way abiogenesis, (derived from EMB), is being applied as an attempt at predicting exo-life, is completely flawed because its basis for prediction is empirically absent, as well as it dealing in non-linear processes, subject to chaotic environments.


I'm not referring to "evolutionary molecular biological research". I'm saying that anything that doesn't make predictions beyond current evidence is completely useless as a scientific theory. It shouldn't even be called a scientific theory.Agreed !
Abiogenesis 'theories', (hypotheses), as they presently stand, when used as a method of predicting exo-life, are completely useless !

The Ptolemaic system of the solar system is an example of a theory that's incapable of making novel predictions and it's not even wrong, as Wolfgang Pauli would say. The research program that you're proposing implies that we cannot proceed theoretically unless we have evidence of a second instance of life, but if we cannot proceed theoretically with one instance there's no guarantee that a second instance is going to bring us any closer to solving the problem of abiogenesis. There's no guarantee that an n-th instance is going to solve the problem. That is because the problem is theoretical, that is, to explain how abiogenesis is possible in this universe.If you acknowledge that the application of Abiogenesis in predicting exo-life elsewhere in the obs universe, is a speculative hypothesis, and not a theory, I have no problem.

Proceeding assuming it is a theory capable of predicting exo-life, is delusional.

By the way, I am not proposing any 'research programs'. Perhaps you forget where this conversation is being conducted ? I am not aware that this board is a platform for reviewing research programs !??


The theory I'm referring to, which explains abiogenesis from established empirically based scientific theories, doesn't exist yet. Since it doesn't exist yet, you cannot know beforehand what it will be capable of predicting.If it doesn't exist yet, then its not a theory. Its a figment of imagination.


"Fundamentally determinable" is a bit vague, therefore it is not at all clear what it is that is falsified, according to you. I proceed on the premise that the universe and life emergence is intelligible , but that's not the same as deterministic. And yet you assume its recurrence is predictable ? That sounds like determinable to me !



Inferences drawn from other areas of science do not inevitably form a solid basis for prediction in complex systems, such as life, or complex biochemical pathways.As I repeatedly tried to make clear: Complexity is a mathematically implicit possibility, and therefore it can follow implicitly from a system defined purely on the basis of physical and chemical laws. These have been computationally demonstrated. The point is that you don't know that these "other areas of science", combined with purely mathematical complexity theory, are insufficient for the development of a theory of abiogenesis capable of making testable predictions.Then put these 'theories' (hypotheses) to the test ! Most have been tested many times over, and returned null or non results! So there is no evidence to support their speculated predictive capabilities in the real world.

At the moment, these synthesised 'theories' (hypotheses) aren't presented as though they are capable of making accurate predictions about emergences of exo-life, even though many folk read this into those very research papers (ie: improperly infer it from them).


Yes, your definition of hypothesis is not agreed upon. It appears to limit hypothesis to mere mechanical inductive generalization; something a computer can be taught to do. You assume that evidence leads like breadcrumbs to a comprehensive theory of phenomena. Inductive generalization leaves hardly any room for human creativity, conceptual inventiveness and originality.Empirical science was created specifically to constrain 'human creativity, conceptual inventiveness, and originality' and direct it towards constructive, tangible progress in the real world.

By not using the tools, a story emerges which is merely sci-fi .. just take a look at the titles in this part of the forum for evidence of such !

I have no problems with speculation, so long as it is recognised as speculation. Those who cannot recognise reality when it presents itself, seem to also have lost the desire and/or skills needed to operate the toolset.

Selfsim
2012-Jun-12, 09:44 PM
Life in the universe, or simply 'life', is a universal. Life on Earth would then be a particular instance of the universal life. A universal has many particular instances, and although the particular instances are differentiated among themselves, they share similarities which make them instances of the same universal. So "life in the universe" is not identical to "life on Earth", simply because a universal cannot be identical to a particular. Even if "life on Earth" is the only instance of "life in the universe", it doesn't make sense to say that they are identical. It would be like saying, one particular apple is identical to the concept of "apple".

The question is then what is the concept of life i.e., the universal of life? Now this universal is something that we can define. So when we define life, we then have a universal called life. There would then be a whole space of possible instances satisfying our definition, our criteria so to speak. The question of the existence of other life is then a question of whether some of the other instances of our concept of life exist in actuality. They may or may not exist in actuality, but they are still logically possible instances of the universal life.The search for exo-life (and subsequent biological testing of samples), IS the test of a speculative version of a universal theory of life.

Until such tests are carried out on a large number of samples sourced from other 'worlds', the theory' (hypothesis), is purely speculative and carries zero significance.

Your opening statement in the above has zero empirical evidence supporting it beyond Earth-life, and has highly questionable theoretical reasoning. At best, it is a philosophically based assertion only and I take exception to the assertion that it represents reality.

Prove it !

Ara Pacis
2012-Jun-12, 10:15 PM
Life in the universe, or simply 'life', is a universal. Life on Earth would then be a particular instance of the universal life. A universal has many particular instances, and although the particular instances are differentiated among themselves, they share similarities which make them instances of the same universal. So "life in the universe" is not identical to "life on Earth", simply because a universal cannot be identical to a particular. Even if "life on Earth" is the only instance of "life in the universe", it doesn't make sense to say that they are identical. It would be like saying, one particular apple is identical to the concept of "apple".Observation suggests otherwise. If there is one apple, then all apples are the one.


The question is then what is the concept of life i.e., the universal of life? Now this universal is something that we can define. So when we define life, we then have a universal called life. There would then be a whole space of possible instances satisfying our definition, our criteria so to speak. The question of the existence of other life is then a question of whether some of the other instances of our concept of life exist in actuality. They may or may not exist in actuality, but they are still logically possible instances of the universal life.I thought that archtypes as a serious concept in empiricism went out of fashion with Plato.

Colin Robinson
2012-Jun-13, 12:43 AM
'The existence of life on Earth, implies life elsewhere', has no basis in direct evidence. It is not a theory. It is a speculative, philosophically based hypothesis, at best.

I would put it this way...

The existence of life on Earth, when combined with the notion that Earth is a planet, raises questions like:

* Do other planets have life on them, or is Earth the only planet with life?

* How common or uncommon is it for a planet to have life on it?

* If other planets do have life, what sorts of life do they have? Are the chemistries and morphologies similar or different to those seen here?

* If other planets do not have life, why not? Is it simply because they differ from Earth in ways that mean nothing could live there? Is it because even on a habitable planet, emergence of life is a low-probability thing?

* If life hasn't happened on other Earth-like and chemically-active planets, what has happened? Are there self-perpetuating chemical systems which are not living organisms?

Questions like these have been considered by scientists and non-scientists even since Copernicus presented his argument that Earth is, in fact a planet.

"We don't know" is not an answer that satisfies our curiosity.

All substantial answers (positive or negative) are speculations...

The all-important further question is:

* What sort of research, if any, may answer questions like these?

Selfsim
2012-Jun-13, 01:27 AM
"We don't know" is not an answer that satisfies our curiosity.So why should curiosity distort the reality of the situation .. that being "unknown" ?
Geee, I thought most humans learned to keep their wants and desires separate from reality around the pre-adolescence years !? (Apparently not !)


All substantial answers (positive or negative) are speculations… So … ??
Why should that result in the reality of our situation being deliberately distorted by the same process of collective consensus about which speculative 'answer' is correct, or not ?

Sure, follow a line of enquiry .. but don't lose track of the reality of the situation .. which is simply and demonstrably, ... "unknown" !


The all-important further question is:
* What sort of research, if any, may answer questions like these?

Certainly not amateurs reading their philosophically based wants-and-desires into research reports, journals, magazines, biased mass media publications, etc, etc.

"The existence of life on Earth, does not imply life exists elsewhere" .. and;

"We know of extant life on one planet only";

… are statements based in demonstrable reality and theory ... they are supportable by all currently available verifiable, independently observational evidence, and they are falsifiable.

Live with it.

Colin Robinson
2012-Jun-13, 02:35 AM
"We know of extant life on one planet only";

We've attempted a scientific search for life on two planets only...


Certainly not amateurs reading their philosophically based wants-and-desires into research reports, journals, magazines, biased mass media publications, etc, etc.

In that case, we'd better rely on professionals, who combine specialist knowledge of planetary astronomy and biology. The astrobiologists.

Mind you, not all astrobiologists consider philosophy irrelevant to what they are doing.

Paul Wally
2012-Jun-13, 02:49 AM
Why is it absurd ?
Without sentience, could a rock distinguish life from non-life ? Sentience is an emergent property of life, and it is a fundamental for distinguishing itself.


What does sentience have to do with whether something is alive or not? A tree is a form of life, and there were living trees on Earth long before sentient humans were there to see it as alive. What is your definition of "life" then?



A hypothesis must be capable of making testable, speculative conclusions.

The purpose of an hypothesis is usually to explain some unexplained phenomenon, e.g. the emergence of life. The speculative part is the hypothesis, and the conclusions (consequences) are implied by the hypothesis for different test conditions.


Once these conclusions are confirmed, it might be regarded as a theory.
No, there is no "once". The number of conclusions depend on the number of possible test conditions, and we cannot know beforehand whether some test is going to refute the hypothesis. An hypothesis is regarded as a theory when it's well confirmed, i.e. when it has already made several successful predictions. But the difference between hypothesis and theory is just a matter of degree of confirmation, so it's not clear when an hypothesis becomes a theory. I don't think it's really important anyway. Both hypotheses and theories are fallible.


In this particular case, at best, it is the track record of successful testable conclusions, which would generate the distinction of the theory's ability to predict.

"Ability to predict" and "ability to make correct predictions" are two different things. A universal theory based on fundamental principles will have the ability to predict consequences for a wide range of possible test conditions. That such a theory will make correct predictions is not something that can be known beforehand.


'The existence of life on Earth, implies life elsewhere', has no basis in direct evidence. It is not a theory. It is a speculative, philosophically based hypothesis, at best.

And I didn't say that, nor did anyone else in this thread say that. So why bring it up?


If your 'theory' of life/abiogenesis has no track record of making successful, testable predictions of life elsewhere, then so be it .. it is useless as a theory for predicting exo-life!

As far as I'm concerned, there is no theory of abiogenesis yet. I'm proposing the possibility of such a theory, and I see no reason why such a theory should be impossible.



Abiogenesis within the field of Evolutionary Molecular Biology (EMB), has tremendous value.
It is the way in which a piece of research is applied, which makes all the difference .. and the way abiogenesis, (derived from EMB), is being applied as an attempt at predicting exo-life, is completely flawed because its basis for prediction is empirically absent, as well as it dealing in non-linear processes, subject to chaotic environments.


I don't know who you're talking about here. I'm sure there's a wide variety of different ideas out there on how to approach the problem.



Abiogenesis 'theories', (hypotheses), as they presently stand, when used as a method of predicting exo-life, are completely useless !
If you acknowledge that the application of Abiogenesis in predicting exo-life elsewhere in the obs universe, is a speculative hypothesis, and not a theory, I have no problem.

I cannot comment because I don't know what you are talking about specifically. Do you have any specific examples of such attempts at predicting exo-life?



If it doesn't exist yet, then its not a theory. Its a figment of imagination.

The important question is of course whether such a theory can exist, which is what I was talking about this whole time. In my view: I don't see why such a theory should be impossible.


And yet you assume its recurrence is predictable ? That sounds like determinable to me !

"Recurrence" means that the same thing happens again. So that word is not applicable here. If exo-life exists, then it exists independently from Earth-life. Maybe it has existed even before Earth-life. In that case we would be the "recurrence". If we had a theoretical explanation of how life in the universe is possible, we should be able to derive the necessary conditions for the likely emergence of life from such a theory. If such a theory is impossible then the emergence of life is unintelligible. If the theory makes wrong predictions then we revise our basic assumptions.


Then put these 'theories' (hypotheses) to the test ! Most have been tested many times over, and returned null or non results! So there is no evidence to support their speculated predictive capabilities in the real world.

Which theories?


At the moment, these synthesised 'theories' (hypotheses) aren't presented as though they are capable of making accurate predictions about emergences of exo-life, even though many folk read this into those very research papers (ie: improperly infer it from them).

Looks like the normal trial-and-error process of science, but this is all very general so I don't know what these theories are that you're referring to.


Empirical science was created specifically to constrain 'human creativity, conceptual inventiveness, and originality' and direct it towards constructive, tangible progress in the real world.

No, empirical science is about testing our ideas against empirical findings.


I have no problems with speculation, so long as it is recognised as speculation. Those who cannot recognise reality when it presents itself, seem to also have lost the desire and/or skills needed to operate the toolset.

Yet it seems that you don't believe that reality presents itself to us. Is a tree alive when nobody's looking?


The search for exo-life (and subsequent biological testing of samples), IS the test of a speculative version of a universal theory of life.

Until such tests are carried out on a large number of samples sourced from other 'worlds', the theory' (hypothesis), is purely speculative and carries zero significance.

Since we don't yet have this universal theory of life, I don't know what it is that you want to test. I'm curious as to exactly what these samples are supposed to test in absence of any theory.


Your opening statement in the above has zero empirical evidence supporting it beyond Earth-life, and has highly questionable theoretical reasoning. At best, it is a philosophically based assertion only and I take exception to the assertion that it represents reality.

The fact that the concept of life is a universal doesn't require empirical evidence. "Life" is definable as a general concept, and that makes it a universally applicable concept. What this means is that it makes sense to ask the empirical question: "Is there life elsewhere in the universe?". If life was not a universally applicable concept, the question would have no meaning.


Observation suggests otherwise. If there is one apple, then all apples are the one.

No, it's not about observation. If the last apple was eaten , we would still have the concept of "apple".


I thought that archtypes as a serious concept in empiricism went out of fashion with Plato.

Well, it's not about what's the latest fashion but about whether you understand what I'm talking about. My point is that if we have a definition of something, that definition applies universally. That's the nature of definition. If we define the concept of life then that concept applies universally.



Sure, follow a line of enquiry .. but don't lose track of the reality of the situation .. which is simply and demonstrably, ... "unknown" !

"Unknown" is not the reality of the situation. The reality of the situation exists whether we know about it or not. I think you should try to get this distinction between "reality" and "knowledge" sorted out.

Ara Pacis
2012-Jun-13, 05:08 AM
No, it's not about observation. If the last apple was eaten , we would still have the concept of "apple".we have apples on earth and nowhere else, that is the observation. If there are no more apples and no more us along with them, then there is no concept.


Well, it's not about what's the latest fashion but about whether you understand what I'm talking about. My point is that if we have a definition of something, that definition applies universally. That's the nature of definition. If we define the concept of life then that concept applies universally.Fashion, in this sense, implies consensus. There is no consensus in modern empiricism, the scientific method and epistemology that archetypes have any meaning.

And what makes you think a hypothesis is separated from theory only by degree? A hypothesis is a logical conjecture based on observation that is, of course, falsifiable. A theory adds accompanying hypotheses, experimentation, repeatability/predictability, etc. And then there's laws that are something else entirely. Again, you're confusing system and category.


"We don't know" is not an answer that satisfies our curiosity.That has little to do with empiricism.


All substantial answers (positive or negative) are speculations...No, explanatory answers that have evidence and are suggestive highly reliable probability estimates are not speculations.

Colin Robinson
2012-Jun-13, 06:00 AM
All substantial answers (positive or negative) are speculations...

No, explanatory answers that have evidence and are suggestive highly reliable probability estimates are not speculations.

The posting you've quoted began with a list of questions about life in the universe. When I said that all substantial answers are speculations, I meant current suggested answers to those questions.

I'd agree that, even in relation to these questions, some suggested answers are more speculative that others.

For instance, compare:

1. the proposition that abiogenesis may have occurred not only on Earth, but also on other worlds with similar compositions, temperatures, etc.

2. the proposition (mentioned by Selfsim in the thread "Is Life Inevitable") that the sorts of chaotic chemistries whose outcome on Earth was abiogenesis, might on other planets lead to self-perpetuating but non-living chemical systems which remain non-living over billions of years.

Proposition 1 (as we keep being reminded) is a generalization from a single example.

Proposition 2, however, is a generalization from no examples at all. There is (as yet) no known case of a planet where the described scenario has occurred.

Proposition 2 is an interesting conjecture, all the same. I'm not sure how much it has been studied... but if it hasn't been, probably it should be. It may turn out to work mathematically. It may even, conceivably, turn out to be true.

Paul Wally
2012-Jun-13, 01:12 PM
we have apples on earth and nowhere else, that is the observation. If there are no more apples and no more us along with them, then there is no concept.

Now I didn't say there would be no more us along with apples. We have concepts of many extinct life-forms, we even have concepts of fictitious life-forms. To have a clearly defined concept of something does not require its existence in actuality.


Fashion, in this sense, implies consensus. There is no consensus in modern empiricism, the scientific method and epistemology that archetypes have any meaning.

Definition of abstract concepts are widely used in both science and mathematics. It has nothing to do with consensus. If life is defined as a certain kind of structural and functional organization, then that mathematical structure defines a space of possibilities all satisfying the definition of the structure. Earth-life forms would then be a particular subset of the entire space of possibilities implied by the definition.


A hypothesis is a logical conjecture based on observation that is, of course, falsifiable.

An hypothesis is a tentative explanation, and explanation usually requires more ingenuity than "logical conjecture based on observation". Sometimes it requires going beyond the evidence to some original principle explaining a wide range of seemingly unrelated phenomena. This way of thinking is called abduction and it's completely different from induction, which seldom if ever explains anything.

Ara Pacis
2012-Jun-13, 06:27 PM
2. the proposition (mentioned by Selfsim in the thread "Is Life Inevitable") that the sorts of chaotic chemistries whose outcome on Earth was abiogenesis, might on other planets lead to self-perpetuating but non-living chemical systems which remain non-living over billions of years.

Proposition 2, however, is a generalization from no examples at all. There is (as yet) no known case of a planet where the described scenario has occurred.

Proposition 2 is an interesting conjecture, all the same. I'm not sure how much it has been studied... but if it hasn't been, probably it should be. It may turn out to work mathematically. It may even, conceivably, turn out to be true.Would weather/geology count?

Ara Pacis
2012-Jun-13, 06:34 PM
Now I didn't say there would be no more us along with apples. We have concepts of many extinct life-forms, we even have concepts of fictitious life-forms. To have a clearly defined concept of something does not require its existence in actuality.It was an analogy. We are the apple.


Definition of abstract concepts are widely used in both science and mathematics. It has nothing to do with consensus. If life is defined as a certain kind of structural and functional organization, then that mathematical structure defines a space of possibilities all satisfying the definition of the structure. Earth-life forms would then be a particular subset of the entire space of possibilities implied by the definition. Abstraction =/= Archetype.

And as a matter of epistemology, how can a categorization scheme nest multiple varieties of something of which only one exists in a universe of possibilities in which none can be empirically predicted to exist? Until you know how life originated here, you have no basis for predicting that such a confluence of events could have happened elsewhere in time and space. Anything else is wishful thinking.


An hypothesis is a tentative explanation, and explanation usually requires more ingenuity than "logical conjecture based on observation". Sometimes it requires going beyond the evidence to some original principle explaining a wide range of seemingly unrelated phenomena. This way of thinking is called abduction and it's completely different from induction, which seldom if ever explains anything.And you still insist it's the same as a theory, only differing by degree?

Colin Robinson
2012-Jun-13, 11:00 PM
Would weather/geology count?

We're discussing whether the process whose outcome on Earth was abiogenesis, could have a different outcome on another planet.

While there are different theories about the process that led to emergence of life here, all theories (as far as I know) involve a range of organic compounds – amino-acids, for example – reacting chemically with one another in the presence of liquid water. I don't know whether or not the long-term result of such a chemical chaos, on another Earth-like planet, can be a chemical system other than life. But if it can, it would presumably be global chemistry very different from geology as we know it, or weather as we know it.

We might in fact need another word ending in -ology, if such a planet is every discovered.

Paul Wally
2012-Jun-14, 11:35 AM
We're discussing whether the process whose outcome on Earth was abiogenesis, could have a different outcome on another planet.

While there are different theories about the process that led to emergence of life here, all theories (as far as I know) involve a range of organic compounds – amino-acids, for example – reacting chemically with one another in the presence of liquid water. I don't know whether or not the long-term result of such a chemical chaos, on another Earth-like planet, can be a chemical system other than life. But if it can, it would presumably be global chemistry very different from geology as we know it, or weather as we know it.

We might in fact need another word ending in -ology, if such a planet is every discovered.

Yes, there is chemistry wherever there is matter. Perhaps we should use the term 'chemical complexity', then we can ask what the level of chemical complexity is on other planets and moons. We wouldn't make the distinction of Earth chemical complexity and exo-chemical complexity, just the class of phenomena called chemical complexity, and Earth biochemistry is an example of chemical complexity in the universe.

Gomar
2012-Jun-14, 03:52 PM
my opinions:
A)There are no alien, space, other-dimensional, non-human tourists, inhabitants, captains and their 1st mates with pointed ears walking around planet Earth. Thus, there are no aliens capable of doing so in the entire galaxy.

B)no alien artifacts, monoliths, probes, ships, signals, housing, structures, etc. exists on planet Earth. If the Egyptian pyramids had been made of steel, or diamonds, or there were elevators, lights, plumbing, high tech tools, alien machinery etc. then anyone would have no doubt that aliens made them.

C)No artificial placement, terra-forming, movements, of stars has ever been observed. Thus, no aliens exist capable of moving stars as easy as we place flowers, homes, roads, etc.

D)No explosions, or unusual activity, or sudden disappearance of stars or galaxies has been detected. Thus, proving, aliens do not wage war, nor blow up each other's worlds.

E)Humans are not caught and sold as slaves by aliens, as Africans were 500 years ago, proving no human slave market exists.

I could go on with many examples as to why aliens have never been, and never will be, on Earth, but I have to feed my dog, and my goldfish
which are my pets... proving I am more intelligent, because I am not their pet.

Ara Pacis
2012-Jun-14, 06:36 PM
Yes, there is chemistry wherever there is matter. Perhaps we should use the term 'chemical complexity', then we can ask what the level of chemical complexity is on other planets and moons. We wouldn't make the distinction of Earth chemical complexity and exo-chemical complexity, just the class of phenomena called chemical complexity, and Earth biochemistry is an example of chemical complexity in the universe.Now this I can agree with. Congratulations, you won the thread. :)

Selfsim
2012-Jun-15, 04:46 AM
Yes, there is chemistry wherever there is matter. Perhaps we should use the term 'chemical complexity', then we can ask what the level of chemical complexity is on other planets and moons. We wouldn't make the distinction of Earth chemical complexity and exo-chemical complexity, just the class of phenomena called chemical complexity, and Earth biochemistry is an example of chemical complexity in the universe.There is chemical complexity on Titan (& Venus, etc). But it seems reasonable to conclude that there are no sentient beings revealing themselves to us by, for example: sending us probes and signals or leaving evidence of past structures where they modified their environments to suit their needs. The complex chemistry there has produced different results from Earth's, (in spite of the same chemicals laws being followed), but under this idea, this would just be another variant instance of chemical complexity in the universe.

Should we then call this 'Titan-complex-chemistry' (TCC) and, perhaps Earth's should be 'Earth-complex-chemistry' (ECC)? Mars has chemical complexity too .. 'Mars-chemical-complexity' (MCC), perhaps? So does Saturn (SCC), Neptune (NCC), Uranus (UCC), Europa (ECC), Enceladeus (EnCC), and so on … they all exhibit environmental dissimilarity from eachother ...

They're all part of the same Solar System … should we call that 'Solar System Chemical Complexity' (SSCC) …?... there are other planetary systems too … should we call them 'Other Planetary Systems' complex chemistry (OPSCC) …?… hmm .. this is getting complicated … We could start by grouping all these by similar broad characteristics of complex chemistry .. and the physical characteristics, which allow for specific complex chemistries capable/not capable of supporting human-like life emergence … now the only planets for which we have any inklings about, when it comes to the presence/absence of Earth-like life, are the local group … should we then model our categories on these, and give them labels like …. Mercurians, Subterrans, Terrans, Superterrans, Neptunians, Jovians, etc, etc ?

This is starting to sound too much like 'planet vs the exo-planets' again … hmmm .. perhaps we could group them by something more generic .. Class M (Mesoplanet), Class T (Thermoplanet), Class P (Psychroplanet), Class hP (HypoPsychroplanet), etc, etc ?…. anything but planet/exo-planet because that non-Copernican perception theme keeps creeping back in again ! (Even though they might all be different in the chemical complexity detail .. which could make all the difference to the end products they produce (ala Titan, Venus, Earth, Kepler xyz etc) … problem is .. we just don't know enough about what level of initial detail distinguishes 'the necessary conditions', in terms of chemical complexity and end-process life products, (from our generalised abiogenesis theory), viewed from astronomical scales .. but we know that the laws of simple chemistry are universal and are fundamental. There is then the concern that we have no idea about how these map into a self-replicating complex cellular lifeform .. we speculate that process must also be universal, (and its end products), in order for our theory to be able to predict, (otherwise it wouldn't be any use). A formulaic approach almost declares that we should choose parameters for our model we know result in consistent, predictable outcomes .. otherwise the theory might become unstable !!

… We know that there exists a class of natural phenomena, where tiny differences in the initial conditions of many of these sub-chemical complex reactions, imposed by perhaps unpredictably changing environments over arbitrary abiogenesis timeframes, could tip the balance, so as to inhibit the progress towards 'life' (which is defined as being Earth life anyway) … and that this might well be the rule, rather than the exception … who knows ?

Regards

Selfsim
2012-Jun-15, 09:51 AM
As an example of how a particular hypothesised abiogenesis reaction may not go along a clearly predictable pathway, check out what Wiki (http://en.wikipedia.org/wiki/Abiogenesis#Further_transformation) has to say .. (Mind you, admittedly, they do point out that citations are required for some of the following, but it does serve as a reminder that there are things not so straightforward about one of the apparent 'basics'):


The spontaneous formation of complex polymers from abiotically generated monomers under the conditions posited by the "soup" theory is not at all a straightforward process. Besides the necessary basic organic monomers, compounds that would have prohibited the formation of polymers were formed in high concentration during the Miller–Urey and Oró experiments. The Miller experiment, for example, produces many substances that would undergo cross-reactions with the amino acids or terminate the peptide chain.
...
More fundamentally, it can be argued that the most crucial challenge unanswered by this theory is how the relatively simple organic building blocks polymerise and form more complex structures, interacting in consistent ways to form a protocell. For example, in an aqueous environment hydrolysis of oligomers/polymers into their constituent monomers would be favored over the condensation of individual monomers into polymers.

Ok.. in spite of these 'doubts' about the viability of this particular process being a good explanation of abiogenesis, (which is not my point), the point I'd like to make is that some chemical variables, like the concentration of inhibiting compounds, are also easily perturbed by micro-environmental fluctuations .. so how many more of such variables exist? If an exo-planet looks like Earth, (when viewed from Earth), does this necessarily imply the same result as what may have happened on Earth, once, billions of years ago? How does one go about developing a theory which could predict those micro-changes which might actually inhibit the abiogenesis ?

syzygy42 has mentioned several other examples of how flux along metabolic pathways, or along signalling pathways in feedback/regulatory networks in present-day biology, can be highly variable. He mentioned that there was a strong argument for a certain amount of noise being required, in order for a biological system to function properly.

How many analogous mechanisms might be involved in the abiogenesis process also, and how sensitive might these be to environmental fluctuations ? What happens when they are perturbed during the process ? Does the end result meet the thresholds for successful input into the next, (perhaps), nested step in the process ?

How can we go about developing a theory which could predict a successful 'exo-outcome', based on things observable from Earth? (Which is Copernically not privileged). Especially when the process might be subject to the same or different dynamicaly unpredictable local weather fluctuations as Earth's ? And how do we make the prediction if these factors are capable of inhibiting the 'expected' outcome ? What really are 'the necessary conditions' .?. and at what scales are they 'the necessary conditions' ?

Does the Copenican Principle have anything to say about why such unpredictable fluctuations can't arise?

Regards

Colin Robinson
2012-Jun-16, 05:49 AM
How many analogous mechanisms might be involved in the abiogenesis process also, and how sensitive might these be to environmental fluctuations ? What happens when they are perturbed during the process ? Does the end result meet the thresholds for successful input into the next, (perhaps), nested step in the process ?

How can we go about developing a theory which could predict a successful 'exo-outcome', based on things observable from Earth? (Which is Copernically not privileged). Especially when the process might be subject to the same or different dynamicaly unpredictable local weather fluctuations as Earth's ? And how do we make the prediction if these factors are capable of inhibiting the 'expected' outcome ? What really are 'the necessary conditions' .?. and at what scales are they 'the necessary conditions' ?

Does the Copenican Principle have anything to say about why such unpredictable fluctuations can't arise?

Could environmental fluctuations result in the chemistry of another Earth-like planet being less complex than the chemistry here? And perhaps stop anything emerging that could undergo darwinian evolution? Maybe yes...

Could environmental fluctuations result in the chemistry of yet another Earth-like planet being more complex than the chemistry here? And perhaps able to undergo a faster and/or more diverse darwinian evolution?

As I understand it, the principle of mediocrity (or Copernican principle) doesn't rule out differences between planets. It just says we may not assume that the differences will necessarily result in our own planet having the most of something.

Regards

Selfsim
2012-Jun-16, 06:51 AM
Could environmental fluctuations result in the chemistry of another Earth-like planet being less complex than the chemistry here? And perhaps stop anything emerging that could undergo darwinian evolution? Maybe yes...

Could environmental fluctuations result in the chemistry of yet another Earth-like planet being more complex than the chemistry here? And perhaps able to undergo a faster and/or more diverse darwinian evolution?

As I understand it, the principle of mediocrity (or Copernican principle) doesn't rule out differences between planets. It just says we may not assume that the differences will necessarily result in our own planet having the most of something.

RegardsWell ya know, Colin ... even though these conversations have been difficult, if one looks back over some of the issues raised, I do find a semblance of a basis for looking at this whole matter, in a different way.

Paul's point has been that he can't see why a generalised theory could not be developed. I have never actually thought that it couldn't. (As usual, we are addressing different matters ... beats me why this always seems to be the case ... ??). Anyway, my only issue is that if one attempts to do this, one should be deliberately cautious not to impose, (even accidentally), a deterministic philosophical view in order to have the outcome predictable ... This way of doing things actually breaks the traditional process by which classical science is normally done. (I'd have to come up with another post/thread to explain where I'm coming from, on this point).

Just a quick comment on your question about: "another Earth-like planet being more complex than the chemistry here? And perhaps able to undergo a faster and/or more diverse darwinian evolution?" ... In a very general sense, if a system gets 'too' complex, I think it it might completely shut down dynamically, as it clogs up with too much complexity .. which interestingly, hints at some optimal value, (and constraints), in order for the dynamics to be sustained. This value should also be tracked in such a generalised model.

I'm sure there are others .. like 'attractors', which would tend to 'rope in' certain 'preferred' behaviours. All of these are generalised parameters one could track (and maybe even simulate) ... its all been considered before, and has many man-years worth of theoretical development effort already poured into it all ... (mainly from the biological sciences stream .. and 'no' .. this hasn't come from anyone who particularly calls themselves an 'Astrobiologist' ;) ).

Randomness is still a very big player in it all, and it is for this reason predictability has to be 'suspended' ... (at least for the time being).

Regards

Paul Wally
2012-Jun-16, 12:53 PM
There is chemical complexity on Titan (& Venus, etc). But it seems reasonable to conclude that there are no sentient beings revealing themselves to us by, for example: sending us probes and signals or leaving evidence of past structures where they modified their environments to suit their needs. The complex chemistry there has produced different results from Earth's, (in spite of the same chemicals laws being followed), but under this idea, this would just be another variant instance of chemical complexity in the universe.

I'm glad we can at least agree on the universality of the concept of chemical complexity.


Should we then call this 'Titan-complex-chemistry' (TCC) and, perhaps Earth's should be 'Earth-complex-chemistry' (ECC)? Mars has chemical complexity too .. 'Mars-chemical-complexity' (MCC), perhaps? So does Saturn (SCC), Neptune (NCC), Uranus (UCC), Europa (ECC), Enceladeus (EnCC), and so on … they all exhibit environmental dissimilarity from eachother ...

Well no. I'm sure you will agree that the name of a planet has nothing to do with the kind of chemistry going on there. So the question is then how we can compare the chemistries of different planets. This is not a difficult problem. Complexity is something measurable in terms of the structural complexity of molecules as well as the dynamic complexity of the chemical processes. These are measurable criteria, and based on such criteria, the chemistries on different planets can be classified. We could go further and compare chemical processes on different planets in terms of their structural similarities, i.e. are there processes structurally similar to Earth biochemical processes?



They're all part of the same Solar System … should we call that 'Solar System Chemical Complexity' (SSCC) …?... there are other planetary systems too … should we call them 'Other Planetary Systems' complex chemistry (OPSCC) …?… hmm .. this is getting complicated … We could start by grouping all these by similar broad characteristics of complex chemistry .. and the physical characteristics, which allow for specific complex chemistries capable/not capable of supporting human-like life emergence … now the only planets for which we have any inklings about, when it comes to the presence/absence of Earth-like life, are the local group … should we then model our categories on these, and give them labels like …. Mercurians, Subterrans, Terrans, Superterrans, Neptunians, Jovians, etc, etc ?

See above.



This is starting to sound too much like 'planet vs the exo-planets' again … hmmm .. perhaps we could group them by something more generic .. Class M (Mesoplanet), Class T (Thermoplanet), Class P (Psychroplanet), Class hP (HypoPsychroplanet), etc, etc ?…. anything but planet/exo-planet because that non-Copernican perception theme keeps creeping back in again ! (Even though they might all be different in the chemical complexity detail .. which could make all the difference to the end products they produce (ala Titan, Venus, Earth, Kepler xyz etc) … problem is .. we just don't know enough about what level of initial detail distinguishes 'the necessary conditions', in terms of chemical complexity and end-process life products, (from our generalised abiogenesis theory), viewed from astronomical scales .. but we know that the laws of simple chemistry are universal and are fundamental. There is then the concern that we have no idea about how these map into a self-replicating complex cellular lifeform .. we speculate that process must also be universal, (and its end products), in order for our theory to be able to predict, (otherwise it wouldn't be any use). A formulaic approach almost declares that we should choose parameters for our model we know result in consistent, predictable outcomes .. otherwise the theory might become unstable !!

As I said, this is about structural comparison between different chemistries, which has nothing to do with the prefix "exo" nor with any planetary classification system that doesn't involve structural comparison between chemistries. As far as I know you are correct that we don't know how the "universal laws of simple chemistry map into self-replicating complex cellular lifeforms", but we can start with simple virtual or artificial chemistry models to see whether something structurally similar to self-replicating units emerge from that. We can then play around with such a model, for example, by randomizing some of variables to see how sensitive the self-replicating outcome is to random variations.





If an exo-planet looks like Earth, (when viewed from Earth), does this necessarily imply the same result as what may have happened on Earth, once, billions of years ago?

It probably doesn't imply the same result, but it might possibly imply a structurally similar (life-like) result, which followed a completely different pathway.



syzygy42 has mentioned several other examples of how flux along metabolic pathways, or along signalling pathways in feedback/regulatory networks in present-day biology, can be highly variable. He mentioned that there was a strong argument for a certain amount of noise being required, in order for a biological system to function properly.

Yes, but life has structure, if it was just noise there would be no biology and no "us" to talk about it. The structure is that which is invariant with respect to random perturbations (noise).


How many analogous mechanisms might be involved in the abiogenesis process also, and how sensitive might these be to environmental fluctuations ? What happens when they are perturbed during the process ? Does the end result meet the thresholds for successful input into the next, (perhaps), nested step in the process ?

Good question, and we don't know yet. That's why we must develop testable models.

Selfsim
2012-Jun-17, 06:29 AM
There is chemical complexity on Titan (& Venus, etc). But it seems reasonable to conclude that there are no sentient beings revealing themselves to us by, for example: sending us probes and signals or leaving evidence of past structures where they modified their environments to suit their needs. The complex chemistry there has produced different results from Earth's, (in spite of the same chemicals laws being followed), but under this idea, this would just be another variant instance of chemical complexity in the universe.I'm glad we can at least agree on the universality of the concept of chemical complexity.Hmm … 'gladness' may be a little premature here, Paul. I was 'trying the concept on' … my previous post was intended to contain a degree of parody of the current way 'exo-life' matters are interpreted by the 'custodians' of all things 'exo-life' (ie: the notorious 'Astrobiologists' ..).

Even universality of chemical complexity (CC), when taken as an assumption for attempting to predict abiogenesis events throughout the universe, is not a 'given'. Such 'universality', may simply tun out to be an indicator of the state of temporal evolution of abiogenetic chemistry, which may, or may not, ultimately evolve into life. I was watching a lecture the other day on the molecular behaviours of solutes/solvents within the vicinity of hydrophilic/hydrophobic surfaces, (liquid water being the solvent). This would not seem to fall into the category of 'complex chemistry' and yet, it was speculated that it may be a fundamental cause of cellular structure evolution.


Well no. I'm sure you will agree that the name of a planet has nothing to do with the kind of chemistry going on there.Well, one of the points I made, was that certain planet classifications are made on the basis of the system environment that planet finds itself located in. Such system environments influence the nature of the chemistry (courtesy of energy contributions, impacts, etc).


So the question is then how we can compare the chemistries of different planets. This is not a difficult problem. Complexity is something measurable in terms of the structural complexity of molecules as well as the dynamic complexity of the chemical processes. These are measurable criteria, and based on such criteria, the chemistries on different planets can be classified. We could go further and compare chemical processes on different planets in terms of their structural similarities, i.e. are there processes structurally similar to Earth biochemical processes?I'm not yet convinced that quantified measures of molecular complexity, necessarily lead to explanations of anything about why, (for eg), a chemical system of say, 50 compounds, differs from another of the same, or even smaller size (??) (For eg: recall the Belousov/Zhabotinsky experiments where the addition of some simple elements and compounds, produced non-linear oscillations, exhibiting a visibly fractal result).

Also, even in the simplest systems, quantification of structural, dynamic, and process simularities (structural) can become extremely cumbersome very quickly, and mathematics/algorithms can easily become overloaded when 3 dimensionality of molecules is considered. When one starts zooming in at different scales, the problem escalates if a fractal structure is encountered .. (eg at the levels of: molecule, cluster of molecules, micro-environment (liquid solvent ?), macro-environment (solids ?), etc). Any of these levels of detail, could make all the difference we might be looking for.

As I said, this is about structural comparison between different chemistries, which has nothing to do with the prefix "exo" nor with any planetary classification system that doesn't involve structural comparison between chemistries. As far as I know you are correct that we don't know how the "universal laws of simple chemistry map into self-replicating complex cellular lifeforms", but we can start with simple virtual or artificial chemistry models to see whether something structurally similar to self-replicating units emerge from that. We can then play around with such a model, for example, by randomizing some of variables to see how sensitive the self-replicating outcome is to random variations. Ok ... so if its to be a generalised model, I suggest we start a new thread.
As a starter, one way of looking at this is from the basics of Complexity Theory ... start out considering the different dynamics we're likely to encounter in our chemical complexity model: static, dynamic, evolving, self-organising. All parameters would have to be variables, which change over time, at different rates.
Global measures would need to apply in all fields (as an assumption), along with others covering unpredictability, non-equilibria, causal loops, and openness.
Some objectives wouldn't go astray either. Eg: explanations of the structures, relative complexity, control methods, constraints, chemistry and physics laws, and they have to be computable (quantified).

Throw all that into an iterative algorithm all at once, and see what pops out, eh ?

Paul Wally
2012-Jun-17, 08:15 PM
I was watching a lecture the other day on the molecular behaviours of solutes/solvents within the vicinity of hydrophilic/hydrophobic surfaces, (liquid water being the solvent). This would not seem to fall into the category of 'complex chemistry' and yet, it was speculated that it may be a fundamental cause of cellular structure evolution.

Chemical complexity is one form of measurable comparison, but certainly not the only one. I think what makes comparison easy in the case of chemistry is it's discrete nature. There is a finite number of chemical elements and they can combine in different possible ways, depending on physical conditions. Of course, chemistry cannot be divorced from physical conditions, but when we focus on measurable and comparable complexity then chemical complexity is one such measure. Surely you must agree that the chemical process of, for example, photosynthesis is much more complex than any chemical processes we've observed on Mars or Titan up till now.


Well, one of the points I made, was that certain planet classifications are made on the basis of the system environment that planet finds itself located in. Such system environments influence the nature of the chemistry (courtesy of energy contributions, impacts, etc).

But a classification system based on general physical characteristics of planets will be completely different from a classification based on chemical complexity. Planets belonging to the same category in the one classification will not necessarily belong to the same category in the other classification system.


I'm not yet convinced that quantified measures of molecular complexity, necessarily lead to explanations of anything about why, (for eg), a chemical system of say, 50 compounds, differs from another of the same, or even smaller size (??)

I think such a measure should depend on some clear quantifiable definition. For instance it wouldn't just be about number of compounds but also about the complexity of the chemical networks wherein these compounds interact within some structurally invariant whole; a system of some sort. You may now ask, but how do we distinguish a complex system from pure random chaos? See Complexity (http://en.wikipedia.org/wiki/Complexity), specifically the part on "Disorganized complexity vs. organized complexity".



(For eg: recall the Belousov/Zhabotinsky experiments where the addition of some simple elements and compounds, produced non-linear oscillations, exhibiting a visibly fractal result).

No problem. Studying such processes may also be useful in understanding life-emergence. Fractal geometry is after all quite common in biological systems too.



Also, even in the simplest systems, quantification of structural, dynamic, and process simularities (structural) can become extremely cumbersome very quickly, and mathematics/algorithms can easily become overloaded when 3 dimensionality of molecules is considered. When one starts zooming in at different scales, the problem escalates if a fractal structure is encountered .. (eg at the levels of: molecule, cluster of molecules, micro-environment (liquid solvent ?), macro-environment (solids ?), etc). Any of these levels of detail, could make all the difference we might be looking for.

Yes, as I said we start with a simple model, preferably something we (and our computers) can handle.



Ok ... so if its to be a generalised model, I suggest we start a new thread.
As a starter, one way of looking at this is from the basics of Complexity Theory ... start out considering the different dynamics we're likely to encounter in our chemical complexity model: static, dynamic, evolving, self-organising. All parameters would have to be variables, which change over time, at different rates.
Global measures would need to apply in all fields (as an assumption), along with others covering unpredictability, non-equilibria, causal loops, and openness.
Some objectives wouldn't go astray either. Eg: explanations of the structures, relative complexity, control methods, constraints, chemistry and physics laws, and they have to be computable (quantified).

Throw all that into an iterative algorithm all at once, and see what pops out, eh ?

Roughly, my approach would be to maybe define some interaction rules between idealized "molecules" (units) to see whether self-replication and evolvability results from that. If it doesn't then invent different generic models until it works. A lot of prerequisite thought needs to go into this though. I think the emergence of self-replication and evolvability is the key theoretical (mathematical) problem. If such an algorithm could be discovered (if it wasn't already) then that would mean the possibility of a general abstract mathematical theory of self-replication and evolvability. Since it would be purely mathematical, it must be applicable wherever a structurally similar situation exists.

willstaruss22
2012-Jun-23, 08:39 AM
I believe we cant even imagine what life in the universe is like, they may thrive in ways that would seem amazing to us. Creatures that have rock bodies, water body, diamond skeleton and very adaptable creatures who can fly then dive into a liquid and breath in that enviromnent. The movies? please we should be thinking way out the box!

Colin Robinson
2012-Jun-24, 02:19 AM
I believe we cant even imagine what life in the universe is like, they may thrive in ways that would seem amazing to us. Creatures that have rock bodies, water body, diamond skeleton and very adaptable creatures who can fly then dive into a liquid and breath in that enviromnent. The movies? please we should be thinking way out the box!

Most of what you describe is already known to exist on Earth.

If you are looking for a creature that can fly, dive and breath in a liquid medium, have you considered the flying fish?

For one with a rock body, how about the reef-building coral polyp?

For a water body... Don't all living bodies on this planet consist largely of water, including the human body?

A diamond skeleton would be something new...

Colin Robinson
2012-Jul-16, 11:43 PM
A comment I made earlier, which drew comments from others...


"We don't know" is not an answer that satisfies our curiosity.


So why should curiosity distort the reality of the situation .. that being "unknown" ?
Geee, I thought most humans learned to keep their wants and desires separate from reality around the pre-adolescence years !? (Apparently not !)



"We don't know" is not an answer that satisfies our curiosity.That has little to do with empiricism.

Unless we had a want/desire to know something – either due to curiosity, or because we hoped to use the knowledge to satisfy some other wish – why would we bother to find out about empirical reality or talk about it?

Science exists precisely because people have not been satisfied with "don't know" answers.