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Maybe that's why you're not willing to apply it to children in the womb?
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Maybe that's why you're not willing to apply it to children in the womb?I just invented it an hour ago.
Maybe that's why you're not willing to apply it to children in the womb?
You mean derailing a conversation between you and Subduction Zone?Perhaps because I recognise your comment as way off-topic and a deliberate attempt to further a personal agenda at the cost of derailing the conversation.
I've given a clear-cut definition (or synonym, if you prefer) for what "kind" is; even using the online etymology dictionary to back it up.I imagine they could invent an undefined word, similar to 'kinds', to confuse the issue. I am going to recommend 'splurgle' as an overarching creationist term for life including all cases which are scientifically fuzzy.
If you mean the characteristics you gave (ie: grow and change, react to the environment, reproduce, have a metabolism etc), all of those are known to depend on the physio-chemical properties of the environment in which they are measured. For example solubility, in an earthly context, is dependent on liquid water being present for use as a solvent in earth-life's biochemistry. The surface temperature of Titan however, is not conducive to the presence of liquid water. DNA/RNA cannot dissolve in the liquid hydrocarbons present on Titan. DNA/RNA therefore could also not interact with other biomolecules at these temperatures .. which is a fundamental necessity for leading towards complexity in known biological systems. Titan's liquid methane solubility range is also too narrow for it to act as a solvent for any other known repeating sequence, longer chain genetic biopolymer candidates. Therefore any of life's known measurables, which depend on solubility in liquid water, would not be evident on Titan's surface.The characteristics are not environment dependent.
Two of the main suggested base 'metabolic' reactions catalysed by Titan's so-called (and mis-named) 'methanogens' are:Bradskii said:But I'll be quite happy to agree with you if you can come up with a different set of characteristics we could use for life in an alien environment.
If you mean the characteristics you gave (ie: grow and change, react to the environment, reproduce, have a metabolism etc), all of those are known to depend on the physio-chemical properties of the environment in which they are measured. For example solubility, in an earthly context, is dependent on liquid water being present for use as a solvent in earth-life's biochemistry. The surface temperature of Titan however, is not conducive to the presence of liquid water.
Traditionally Western Civilisation until the mid 17th to 18th centuries (which can equally be called Christendom) had a concept of graded souls. There was the Nutritive soul in plants, then the Animal soul, going up to the Rational soul in humans. Thereafter with the breakdown of old-style Scholastic Aristotleanism and the increasing adoption of the mechanical metaphor (of the soul in some sense 'driving' the body) perhaps from Descartes' influence, the idea of animals and plants being 'soulless' arose (or some idea of Transcendentalism or panpsychism based on classical philosophy). The concept of Life itself was also much looser before, as mediaevals were happy to ascribe life to the stars for instance, and debates on whether rivers were not in a sense 'alive' not unheard of. It is more the rigid post-Baconian and Linnaean nature that is at play today, creating our classifications that always has exceptions somewhere.(Interesting side issue - if trees lack souls do they have some kind of 'life force' to differentiate a tree from a piece of wood? This is a concept associated with animism. Is there a Christian equivalent?)
Re: my underline - That’s not exactly what I was saying there .. Let me go a little deeper (to clarify):Bradskii said:How does a lack of water prevent growth and change? Or prevent some life form reacting to the environment? Or reproduce? Is it possible to class something as alive if it doesn't grow? Or cannot react to it's environment (how would it feed?).
I thought I just did in my last post(?), as follows:Bradskii said:If you like you can give me some other characteristics of life other than those we use for terrestrial life that might be considered for alien life.
Life is critically dependent on transport of polar molecules within and between cells. I can't see any life processes functioning without a physical inter or intra-cell transport mechanism.
I thought I just did in my last post(?), as follows:
A measurable effect on the hydrogen mixing ratio in the troposphere, at certain levels of consumption, might be indicative of hypothetical Titan lifeforms. Anomalous depletions of acetylene and ethane, as well as hydrogen at the surface, would be indicative of one such non terrestrial lifeform .. (ie: one that is apparently envisaged by some, as possibly existing in a Titan context/environment).
The only way we'll know some alien life's characteristics, is by way of measurements and then noticing that those measurements are distinguishably dissimilar from those of the backdrop/environment from which that isolate was sampled. Those measurements then become the basis for what distinguishes life from its environment (and becomes part of its definition in that environment).Bradskii said:But we're not looking for what might indicate life. We're discussing the characteristics of life. Water or methane or oxygen or depletion of methane and ethane is not a defining characteristic of life. It's an indication that life might exist (notwithstanding that we could find an exoplanet soaked in water with abundant oxygen and lots of methane but with zero life). In which case we could try to find something that had the characteristics as previously discussed. If we do, then we have found life.
The only way we'll know some alien life's characteristics, is by way of measurements and then noticing that those measurements are distinguishably dissimilar from those of the backdrop/environment from which that isolate was sampled. Those measurements then become the basis for what distinguishes life from its environment (and becomes part of its definition in that environment).
'Try{ing} to find something that had the characteristics as previously discussed', is only known to be valid in the case of Earth-life. We don't have a clue as to whether those characteristics exist elsewhere. That is the real problem we're dealing with here. Researching a totally new, non-Earthly environment is not driven by some logical test which assumes the 'likely' existence of Earth-life somewhere else. That is not a scientific approach to the problem of dealing with the virtually unknown .. We ain't rollin' dices when researching a totally new, non-Earth environment, y'know? And that's in spite of how most people here, think science operates .. (I'm not just singling yourself out here ..).
The evidence for what I'm saying here, comes largely from the ambiguous outcomes of the Mars Viking probe life experiments of the 1970's. Those experiments ultimately failed because they approached the problem from that same flawed unscientific way of thinking
The environment some sample of sample of interest is isolated from, is 100% relevant .. its the baseline for comparison. We for example, are products of our environment .. if you don't accept this, then where do you think our life came from?Then you need to give possible alternative defining characteristics. What you've offered so far is possible evidence of life. If there are no alternatives characteristics, then how do we know when we've found life? And as I said, the environment is irrelevant. But proffer any environment you feel helps your case.
The environment some sample of sample of interest is isolated from, is 100% relevant .. its the baseline for comparison. We for example, are products of our environment .. if you don't accept this, then where do you think our life came from?
(As you argue your point there, you will be up against the mountains of biological evidence including evolution back to LUCA and the evidence of the standard genetic code).
Just because one cannot state a 'possible defining characteristic' which might satisfy your emotional demands, doesn't erase the real problem we're all confronted with when it comes to exo-life and the possibility of testing another instance of Abiogenesis elsewhere.
We cannot know, what we don't know yet .. for goodness sake!
A handful of people think it possible the failure was in the rejection of the positive results from two of the the three tests and unjustified confidence in the data from the GCMS that failed to detect organic matter. I'm one of those people. Another decade should tell us who is right.The evidence for what I'm saying here, comes largely from the ambiguous outcomes of the Mars Viking probe life experiments of the 1970's. Those experiments ultimately failed because they approached the problem from that same flawed unscientific way of thinking
NASA's astrobiology section defines it as “... a self-sustaining chemical system capable of Darwinian evolution”. But there are more general definitions - Erwin Schrodinger said, "Life is something that goes on doing something much longer than you would expect it to", which is a bit too general and subjective for my taste; philosopher Paul Churchland says life is, "Any semi-closed physical system that exploits the internal order it already possesses, and the energy flux passing through it, in such a way to maintain and/or increase its internal order"; Wikipedia gives some more... and those characteristics change depending on the physical context (the environment) and on the behaviours of the specimen within that context. Their preconceptions (including the definition of life) of 'how life must be', (in your scenario there), could quite easily be completely amiss in a really non-earth-like context.
No matter how much they talk it up, they don't know what they're looking for until 'a specimen of interest' shows up in some radically different non-earth environment. In the case of Titan, the arm-wavers have conjured up a scientifically meaningless lifeform called a 'methanogen' (because it will have to based on the methane). However the term 'methanogen' only has meaning in an Earth-life context. We have anaerobic methanogens here on Earth .. but their base chemistry is still related to all other Earth-life .. which will be nothing like Titan's. The term is being abused for the sake of stirring up interest in alien life.
What I'm saying here is that the definition of life is totally context dependent. We will have to restart the process of redefining it in the context of an alien landscape and our preconceived definition/notions and tests for it, will also have to be restarted from scratch in that new context.
So Curiosity's GCMS-CG is pretty well a state of the art instrument. It detected organics (chlorobenzene) at the Cumberland mudstone in Gale crater and some other reasonable (in mass) molecules. The controversy over Levin's experiments still continues however, (with still no consensus on detection methods). MSL/SAM has made no further announcements about more complex organics detection since, (AFAIK).A handful of people think it possible the failure was in the rejection of the positive results from two of the the three tests and unjustified confidence in the data from the GCMS that failed to detect organic matter. I'm one of those people. Another decade should tell us who is right.
.. and yet Darwian evolution is not possible under the low temperatures and physically absent liquid water conditions on Titan's surface (and methane lakes).NASA's astrobiology section defines it as “... a self-sustaining chemical system capable of Darwinian evolution”.
Yes .. a different definition to suit the particular context/environment under study .. Highlights what I've been saying about the importance of thoroughly categorising the natural environment as a first step .. which may/may not lead to concluding/diagnosing 'life' within that specific environment/context.FrumiousBandersnatch said:But there are more general definitions - Erwin Schrodinger said, "Life is something that goes on doing something much longer than you would expect it to", which is a bit too general and subjective for my taste; philosopher Paul Churchland says life is, "Any semi-closed physical system that exploits the internal order it already possesses, and the energy flux passing through it, in such a way to maintain and/or increase its internal order"; Wikipedia gives some more.
This one showed up recently .. which I tend to think of as being a rather well considered and well modelled attempt which might lead to better analysis techniques of remotely sourced mass spectrographic data. Well worth the read, (IMHO):NASA's astrobiology section defines it as “... a self-sustaining chemical system capable of Darwinian evolution”. But there are more general definitions - Erwin Schrodinger said, "Life is something that goes on doing something much longer than you would expect it to", which is a bit too general and subjective for my taste; philosopher Paul Churchland says life is, "Any semi-closed physical system that exploits the internal order it already possesses, and the energy flux passing through it, in such a way to maintain and/or increase its internal order"; Wikipedia gives some more.
The search for alien life is hard because we do not know what signatures are unique to life. We show why complex molecules found in high abundance are universal biosignatures and demonstrate the first intrinsic experimentally tractable measure of molecular complexity, called the molecular assembly index (MA). To do this we calculate the complexity of several million molecules and validate that their complexity can be experimentally determined by mass spectrometry. This approach allows us to identify molecular biosignatures from a set of diverse samples from around the world, outer space, and the laboratory, demonstrating it is possible to build a life detection experiment based on MA that could be deployed to extraterrestrial locations, and used as a complexity scale to quantify constraints needed to direct prebiotically plausible processes in the laboratory. Such an approach is vital for finding life elsewhere in the universe or creating de-novo life in the lab.
By what is it determined that Darwinian evolution isn't possible.. and yet Darwian evolution is not possible under the low temperatures and physically absent liquid water conditions on Titan's surface (and methane lakes).
Yet one particular NASA Ames Planetary scientists publishes papers on 'the possibility' of Titan based methanogenic 'lifeforms'? Why is that?
Yes .. a different definition to suit the particular context/environment under study .. Highlights what I've been saying about the importance of thoroughly categorising the natural environment as a first step .. which may/may not lead to concluding/diagnosing 'life' within that specific environment/context.
Life's definition is far from being established as a universal 'given' .. yet everyone throws around the term as though it is!?
2LoT, come on the argument has been used before.By what uis it determined that Darwinian evolution isn't possible
there.
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