Mars Life Confusion

[renormalised (Carl)]

They want to goto Gale Crater because it was most likely the bottom of a large lake. It's a good place to start when looking for the presence, past or present, of life. But that doesn't mean it's going to be found there. Nor does it mean that not finding it there that Mars never had life. As I said previously, the only surefire way they'll know if there was life there or not, is to go there and do the exploring ourselves. We're far better at finding fossils and/or living organisms than computers and machinery/detectors are, and if we get fooled sometimes with what we find, imagine how much more difficult it is for a probe. It can't think, nor extrapolate the possibilities....we can.

[renormalised (Carl)]

Well, it's a good example and one that NASA uses frequently to model Mars on. As I said, you may not find any life in the desert, but that's not to say the next valley over isn't full of mountain lions and vicunas

[renormalised (Carl)]

Originally Posted by CraigS

Yep I agree … however reference source is here and it says '1000' ... (blame Michael Schirber).

Cheers

If it was 1000 bar, as Schirber says, the ancient martian atmosphere at "sea level" would've been as dense as water. You could just about swim in it!!!!.

[CraigS]

Originally Posted by renormalised

Nor does it mean that not finding it there that Mars never had life.

Can you name one place on a planet where we know life emerged, where life cannot be found ?

What then, is the scientific basis for your above statement ?

Cheers

[renormalised (Carl)]

Originally Posted by CraigS

Can you name one place on a planet where we know life emerged, where life cannot be found ?

What then, is the scientific basis for your above statement ?

Cheers

Yep....the core of our planet

Unless, of course, you subscribe to the Hollow Earth Theory

Saying that a planet has never had life, based on evidence from only one or two spots which may or may not have been conducive to having life there in the first place isn't very scientific at all. You haven't exhausted all the possibilities for both the number of sites and degrees of habitation, for a start. And, you're basing your deliberations and prognosis on a statistically insignificant number of sampling sites. However, if they covered a good deal of the surface of the planet and also undertook a reasonable number of borehole surveys and never found any evidence for life on the planet, then I would be inclined to say that Mars never had any life on it. It also goes without saying that this would be in addition to other surveys done of the hydrological and other geological processes which may either support life or possibly mimic it (e.g. inorganic methane production etc).

That's why I take most of these surveys by probes, whilst interesting and rewarding in a limited, specific scientific sense, with a grain of salt. They're not definitive and never will be. Relying on their finding as somehow being able to provide definitive answers to any question is not the way to go about conducting a survey for something as complicated as looking for life. You can only use what they find as possible indicators, but of a rather limited nature. Nothing more or less.

[CraigS]

Originally Posted by renormalised

Yep....the core of our planet

.. Well, I did say, "Can you name one place on a planet" … as distinct from "in a planet"
Clearly, the proportion of of life bearing locations on the surface of this planet, completely swamps any locations where life may be absent and this then sets the criterion for sampling the surface of Mars.

Originally Posted by renormalised

… you're basing your deliberations and prognosis on a statistically insignificant number of sampling sites. However, if they covered a good deal of the surface of the planet ...
... a statistically insignificant number of sampling sites.

How much is 'a good deal', and what would be ‘a statistically significant number’ of samples ... and what is the scientific basis for estimating this?
How much of the surface of a life bearing planet supports life, and what does this tell us about how much of the surface has to be searched ?

Originally Posted by renormalised

That's why I take most of these surveys by probes, whilst interesting and rewarding in a limited, specific scientific sense, with a grain of salt. They're not definitive and never will be. Relying on their finding as somehow being able to provide definitive answers to any question is not the way to go about conducting a survey for something as complicated as looking for life. You can only use what they find as possible indicators, but of a rather limited nature. Nothing more or less.

I think I can see that you'll never be satisfied with any negative finding returned by a robotic probe. What would be your stance if it returns a ‘positive’ result and what is the scientific basis for this ?

We can only work with the tools/technologies we currently have, and are able to send there. The framing of the mission goal is important here, because it is, for all intents and purposes, the definition of the ‘experiment’. The results and conclusions of that experiment should be expressed in terms of whatever they set out to accomplish ... as defined in the wording of those goals.
(Sounds like another post, to me .. see my next one).

Anyway, we should review this aspect once the thing gets there and starts producing results .. we have no idea of what will happen .. it may not even make it to the Crater, anyway.

Cheers

[CraigS]

It seems the title I chose for this thread might be appropriate, as there is clearly a lot of confusion about the MSL/Curiosity mission goals.

So, straight from the horse's mouth (NASA/JPL's site) …

The MSL mission has four primary science objectives to meet the overall habitability assessment goal:

1) The first is to assess the biological potential of at least one target environment by determining the nature and inventory of organic carbon compounds, searching for the chemical building blocks of life, and identifying features that may record the actions of biologically relevant processes.

2) The second objective is to characterize the geology of the landing region at all appropriate spatial scales by investigating the chemical, isotopic, and mineralogical composition of surface and near-surface materials, and interpreting the processes that have formed rocks and soils.

3) The third objective is to investigate planetary processes of relevance to past habitability (including the role of water) by assessing the long timescale atmospheric evolution and determining the present state, distribution, and cycling of water and carbon dioxide.

4) The fourth objective is to characterize the broad spectrum of surface radiation, including galactic cosmic radiation, solar proton events, and secondary neutrons.

So, notice that they are searching for present-day evidence of past habitability environments … so, I stand corrected .. and I retract what I implied earlier .. ie: something along the lines of: 'this is the first time they've gone specifically searching for life' … clearly this is not strictly accurate.

My previous statement is as much a result of the media spin on the true mission objectives, (ie: it was not intentionally, my own view).

Cheers

[CraigS]

More detail (for the record) …

MSL will investigate a site that shows clear evidence for ancient aqueous processes based on orbital data and undertake the search for past and present habitable environments. Assessment of present habitability requires an evaluation of the characteristics of the environment and the processes that influence it from microscopic to regional scales and a comparison of those characteristics with what is known about the capacity of life, as we know it, to exist in such environments. Determination of past habitability has the added requirement of inferring environments and processes in the past from observation in the present. Such assessments require the integration of a wide variety of chemical, physical, and geological observations.

MSL is not a life detection mission and is not designed to detect extant vital processes that would betray present-day microbial metabolism. Nor does it have the ability to image microorganisms or their fossil equivalents. MSL does have, however, the capability to detect complex organic molecules in rocks and soils.

If present, these might be of biological origin, but could also reflect the influx of carbonaceous meteorites. More indirectly, MSL will have the analytical capability to probe other less unique biosignatures, specifically, the isotopic composition of inorganic and organic carbon in rocks and soils, particular elemental and mineralogical concentrations and abundances, and the attributes of unusual rock textures. The main challenge in establishment of a biosignature is finding patterns, either chemical or textural, that are not easily explained by physical processes.

MSL will also be able to evaluate the concentration and isotopic composition of potentially biogenic atmospheric gases such as methane, which has recently been detected in the modern atmosphere. But compared to the current and past missions that have all been targeted to find evidence for past or present water, the task of searching for habitable environments is significantly more challenging (e.g., Grotzinger, Nature Geoscience, 2009).

Primarily, this is because the degree to which organic carbon would be preserved on the Martian surface–even if it were produced in abundance–is unknown.

I can't believe that they're not sending up a microscope capable of looking for micro-organisms or their fossil remnants ! (See text in bold above).

Cheers

[renormalised (Carl)]

Originally Posted by CraigS

.. Well, I did say, "Can you name one place on a planet" … as distinct from "in a planet"
Clearly, the proportion of of life bearing locations on the surface of this planet, completely swamps any locations where life may be absent and this then sets the criterion for sampling the surface of Mars.

Well, let's not get into semantics here

You can't use the Earth as a sampling criteria for another planet simply because of the differences which which each planet exhibits. That's why trying to extrapolate from one given example is dangerous, scientifically, and statistically meaningless. You get skewed and inaccurate answers. Or you get the wrong impression about what's going to occur....i.e. your theories are predicated on a set of assumptions which may or may not even be applicable in the circumstances. Nature doesn't follow the scientific method, nor does it have to follow any set of assumptions made by anyone, nor does it have to follow anyone's expectations. That's what makes this kind of exploration interesting. Don't discount anything, just because it doesn't meet your previous assumptions and expectations.

Originally Posted by CraigS

How much is 'a good deal', and what would be ‘a statistically significant number’ of samples ... and what is the scientific basis for estimating this?
How much of the surface of a life bearing planet supports life, and what does this tell us about how much of the surface has to be searched ?

That's about as inane as saying "how long is a piece of string"...it can be as long as you like, or not. It all depends on your definition of what a reasonable amount of coverage is going to be, based on the limitations of your study, but it would most certainly be more than one sampling location. That would tell you very little, either way. However, if you had, let say, 10 or so locations spread widely over the surface of the planet and you were getting results from all of them, either way, then you could make some conclusions from that. But the more you sample, the better your results and the stronger your conclusion can be. If you were getting ambiguous results no matter what you did, then you would have to reevaluate your previous assumptions and your theories and try another tack.

Originally Posted by CraigS

I think I can see that you'll never be satisfied with any negative finding returned by a robotic probe. What would be your stance if it returns a ‘positive’ result and what is the scientific basis for this ?

Robotic probes are a "suck it and see" proposition. They limited by their capacity to do only that which they're programmed to do and they can't take advantage of the unexpected or "leap over logic" to look in new and different ways. They can only do what they're designed to do and if the designers get it wrong to begin with or their assumptions about what to find are biased in any way, then the results returned will reflect this. The Viking probes were a prime example of this. They got the results they did because they didn't understand Mars and their assumptions as to what would be there and how they were going to go about testing them were faulty. They produced ambiguous results....yes/no/maybe. Even if the present mission produced positive results, I would still want hands on confirmation and study of a much wider set of samples before I was ready to make a conclusive statement either way. If I was to find irrefutable evidence for fossilised life on the planet, then the case would be closed. If I found nothing after running many tests and sampled a good proportion of the planet, then it would be the same deal. If that sampling meant hundreds of rock samples and many drill cores from a dozen sites or more, then so be it. That's what it will take.

Originally Posted by CraigS

We can only work with the tools/technologies we currently have, and are able to send there. The framing of the mission goal is important here, because it is, for all intents and purposes, the definition of the ‘experiment’. The results and conclusions of that experiment should be expressed in terms of whatever they set out to accomplish ... as defined in the wording of those goals.
(Sounds like another post, to me .. see my next one).

The present set of tools is inadequate for the task. All they can do is give us a few extra bits of information with which to prove up our previous assumptions a little bit better than what they are at present. They will not give us a definitive answer. You may have a friend overseas that you correspond regularly with over the internet via webcam. You may get to know them reasonably well but you'll never know what they're really like until you actually go over and meet them in person. That's when you get your definitive answer. It's the same here.

Originally Posted by CraigS

Anyway, we should review this aspect once the thing gets there and starts producing results .. we have no idea of what will happen .. it may not even make it to the Crater, anyway.

Cheers

Not in one piece, at least

[renormalised (Carl)]

Here's a clanger....what if the life on Mars was silicon based. There's nothing stopping it from being as such and silicon is far more abundant an element in the Solar System than carbon is. How do you test for silicon based life??? They might drive right over the top of a whole patch of silicon based organisms and not even recognise them as even being alive by our definition.

That's the whole problem here....these probes are limited in so many ways. It's the reason why people need to go there and do the groundwork. Despite the paradigms under which they work, people aren't restricted by them unless they want to be.

[renormalised (Carl)]

Originally Posted by CraigS

More detail (for the record) …



I can't believe that they're not sending up a microscope capable of looking for micro-organisms or their fossil remnants ! (See text in bold above).

Cheers

With most of them, you need an electron microscope of one sort or another to do this and they're a little too large and power hungry to be sticking on a probe...even one as large as Curiosity

You can't rely on the assumption that the Martian microbes exhibited the characteristics of some of their Earthly counterparts and produced macroscopic structures...like microbe mats and stromatolite like structures. Any confirmation of this will come through the exploration of the rocks of the planet as a whole, not from one locality only.

It only goes to prove my case in point.

[CraigS]

Actually Carl, standing back and looking at this thread from a distance, I think I was on exactly the right track from the OP … there is a lot of confusion about how, and what to look for on Mars. I'm not even convinced that sending humans there for a reasonable amount of time, might provide definitive answers to the fundamental questions.

I think your approach (as usual) seems to be to take a bigger step beyond the 'what's known' .. and ultimately in the hunt for exo-life (as-we-don't-know-it), this may be a more effective and efficient way to get the real answers.

Unfortunately, the real world just doesn't work that way and we're saddled with exploration budget and scientific process constraints. Just getting another probe to Mars is probably a huge step forward for NASA at the moment, anyway. (I'm also not attempting, in any way, to criticise your views here .. and I know you're passionate about changing this in fairly radical ways (let's also try to not go down this discussion path on this particular thread .. I understand where you're coming from on this..)).

But working within those constraints, it seems to me that what this mission is doing, is providing more data which ultimately will build a more evidence-based description of life-supporting Habitable Zones (HZ). If they find the remnants of bio-signs, (as defined from an earth-based extremophile model), in the crater .. it would be a huge bonus and would demonstrate that we were well and truly on the right track in our thinking about exo-life .. and where to look for it .. and what to look for.

But in the case of not finding any bio-signs, because all our best effort scientific knowledge has led us to the highest probability HZ we presently know of, and maybe yields a negative result, also says something definitive about HZs and our present expectations about life elsewhere. Exactly what it says, depends on the data findings .. we'll just have to wait and see.

If you think a negative finding says little/nothing, then here's another question: "Why aren't we actively looking for life on the moon ?" Clearly, no scientist takes this possibility more seriously than the Mars case … and no-one is seriously looking on the Moon. So the findings of moon exploration have led us to view the moon is 'dead' and science moves forward on this basis. The presence of humans on the moon made no difference to the conclusion, either. So why would this not happen in the case of Mars after several probes have checked out the scene ?

I don't understand what you mean by 'Silicon based life'. The NASA Astrobiologists themselves, have said that they can only look for what we'd recognise. If we are incapable of recognising something as a life form, then it might as well not exist as far as we're concerned .. its like saying that pink-unicorns exist, and rule the universe .. 'there's no evidence for them but we know they exist' … sorry .. this just doesn't carry any weight in science. This is a faith-based if the pink unicorns don't expose themselves or influence us in a recognisable way. If they serendipitously give off C12 in methane gas ... then that's different, and I might celebrate the findings with the believers, and consider them as candidates for 'reality'.

Cheers

[CraigS]

Ok .. a summary of some info comparing Carbon ( C) vs Silicon (Si) biochemistry follows (from Wiki):

- Si has the same valency as C (ie: four), so it is theoretically large enough to carry biological information
- Si lacks the ability to form chemical bonds with diverse atoms .. (req'd for metabolism), when compared with carbon;
- has difficulty forming double, triple or covalent bonds, thus it lacks the diverse compound morphologies formed by Carbon (important for biochemistry);
- compounds of H and Si are highly reactive with water and long chains of these decompose;
- silicones (polymers of Si and O) are more stable than hydrocarbons in suphuric acid environments (quite common);
- complex long chain silicones are less stable than their C counterparts;
- silicon dioxide is a non-soluble solid at temps where water is liquid;
- Si based life breathing Oxygen would produce a solid by-product, thus respiratory organs would be filled with sand. This can be overcome at very high temperature or pressure environments .. (ie: not Mars surface);
- as at 1998, in the interstellar medium, 84 molecules are based on C, whilst only 8 are based on Si. Of those eight compounds, four also include C;
- the cosmic abundance of C to Si is about 10:1, (complex carbon compounds are thus more abundant to support C based foundation for life on planetary surfaces, than Si compounds);
- however, the abundance of Si to C on Earth is about 925:1 and yet, terrestrial life is C based. Thus it seems that C is more successful at forming life, in spite of its less comparative abundance, than Si;
- compounds formed by Si block the flow of heat, nonetheless biogenic silica is used by some life on Earth. Thus lifeforms comprising combinations of C and Si could achieve metabolism and digestion;

So, in terms of maximising the chance of detecting life on Mars' surface, from the above physical facts perspective, it would seem to make sense to constrain the probe/laboratory design around detecting Carbon based organic life … over the Si based life alternative.

Cheers

[renormalised (Carl)]

Originally Posted by CraigS

Ok .. a summary of some info comparing Carbon ( C) vs Silicon (Si) biochemistry follows (from Wiki):

- Si has the same valency as C (ie: four), so it is theoretically large enough to carry biological information
- Si lacks the ability to form chemical bonds with diverse atoms .. (req'd for metabolism), when compared with carbon;
- has difficulty forming double, triple or covalent bonds, thus it lacks the diverse compound morphologies formed by Carbon (important for biochemistry);
- compounds of H and Si are highly reactive with water and long chains of these decompose;
- silicones (polymers of Si and O) are more stable than hydrocarbons in suphuric acid environments (quite common);
- complex long chain silicones are less stable than their C counterparts;
- silicon dioxide is a non-soluble solid at temps where water is liquid;
- Si based life breathing Oxygen would produce a solid by-product, thus respiratory organs would be filled with sand. This can be overcome at very high temperature or pressure environments .. (ie: not Mars surface);
- as at 1998, in the interstellar medium, 84 molecules are based on C, whilst only 8 are based on Si. Of those eight compounds, four also include C;
- the cosmic abundance of C to Si is about 10:1, (complex carbon compounds are thus more abundant to support C based foundation for life on planetary surfaces, than Si compounds);
- however, the abundance of Si to C on Earth is about 925:1 and yet, terrestrial life is C based. Thus it seems that C is more successful at forming life, in spite of its less comparative abundance, than Si;
- compounds formed by Si block the flow of heat, nonetheless biogenic silica is used by some life on Earth. Thus lifeforms comprising combinations of C and Si could achieve metabolism and digestion;

So, in terms of maximising the chance of detecting life on Mars' surface, from the above physical facts perspective, it would seem to make sense to constrain the probe/laboratory design around detecting Carbon based organic life … over the Si based life alternative.

Cheers

Yes....all true. However, silicon based lifeforms would fall under the category of "life as we don't know it". That's what I said originally...how would we test for it. Especially if our life paradigm is looking for carbon based life, or lifeforms that metabolise, etc, in a similar fashion to carbon based forms.

What if the silicon based lifeforms were all solid state and crystalline in nature, which would most likely be the case. How are we going to test for that?? Would you even recognise it as being alive??. You could walk right past it and not even notice. Given our present technology and scientific paradigm in this respect, detecting such lifeforms would be very difficult. For one, we're not looking for them, and we also don't have the equipment to distinguish a silicon crystalline lifeform from a lump of rock.
They may or may not exist, granted, but we'll never know unless we go looking for them...or meet up with one at some stage. We're biased because we are carbon based and it's much easier to detect. But that doesn't mean we should ultimately limit ourselves to carbon based life. To do so would be wholly unimaginative and scientifically narrow minded. Even if we never find any, at least we'd have explored the possibilities.

Just had a funny thought....imagine having a deep conversation with what appeared to be a large lump of rock crystal

Wait a minute, there's some people who already do this!!!!!

[CraigS]

Down the bottom of that Wiki page, are several references to a major paper, (book actually), authored by the "Committee on the Limits of Organic Life in Planetary Systems, Committee on the Origins and Evolution of Life, National Research Council" its called: "The Limits of Organic Life in Planetary Systems; The National Academies Press, 2007".

All of the questions you have so far posed, Carl are covered in some way, shape, or form in this publication. Its purpose was primarily to provide guidance for NASA on the search for exo-life. The table of contents is here.

Of particular interest is the Chapter on "Strategies to Mitigate Anthropocentricity".

Here's a quote from that Chapter:

Finally, the committee considered more exotic solutions to problems that must be solved to create the emergent properties that we agree characterize life. It considered a hierarchy of “weirdness”:

- Is the linear dimensionality of biological molecules essential? Or can a monomer collection or two-dimensional molecules support Darwinian evolution?
- Must a standard liquid of some kind serve as the matrix for life? Can a supercritical fluid serve as well? Can life exist in the gas phase? In solid bodies, including ice?
- Must the information content of a living system be held in a polymer? If so, must it be a standard biopolymer? Or can the information to support life be placed in a mineral form or in a matrix that is not molecularly related to Darwinian processes?
- Are Darwinian processes and their inherent struggle to the death essential for living systems? Can altruistic processes that do not require death and extinctions and their associated molecular structures support the development of complex life?

After a hundred pages or so, and eight Chapters, the final conclusions/recommendations are here.

It seems to me that the MSL/Curiosity Rover technologies are a direct flow-on from these recommendations.

There has been a lot of consideration of all the aspects you raise .. and then more.
The conclusions have given rise to the technologies being sent along with MSL/Curiosity.

There's very few questions left in my mind that the Mars probe is maximising the chance of detecting recognisable bio-signs, in the most probable Habitable Zone presently accessible, and known to humans.

The definitional scope of this 'experiment' is sufficiently tight to enable very specific conclusions, within the practical constraints of the mission. The instruments themselves are designed to return precise results to minimise measurement uncertainties and rule out inaccurate readings.

What the conclusions of the measurements will be, depends on the data, and the conditions under which it is gathered.

One possible outcome could quite easily be, in the case of "no-organic chemistry bio-signs detected" in this high probability HZ, that there are indeed, "no-organic chemistry bio-signs detected" in this high probability HZ, of a high probability HZ planet.

If this were to happen, I would suggest a big re-think of HZ definitions in terms of environment, biologies, search strategies, missions, and detection technologies, would be a very rational outcome.

The opposite findings, I would think, would probably be sufficient to justify a manned mission at some stage in the future.

Cheers

[renormalised (Carl)]

Look what the paper is resting upon, Craig...organic life. In other words, carbon based or analogues of carbon based life. Even their mineral based "information carriers" are still within the confines of an organic chemistry of some sort. Darwinian evolution, etc. I've seen this paper before. They haven't covered anything to do with possible inorganic lifeforms, at least none that I can remember in the report.

What about lifeforms that are completely devoid of anything to do with organic chemistry. A solid state, crystalline lifeform would fit that description. If you saw a crystal sticking out of the ground and all you could see was some play of light through the crystal, could you tell if it was a living organism or not??. Given everything that was written in that report and the raison detre of the Curiosity mission??. I'd dare say no.

What about something that appears as an interstellar dust cloud. Have a read of Frank Boyle's "The Dark Cloud".

What about a lifeform that is nothing more than a type of living energy?? How do you begin to categorise that?? How do you recognise it??

In any case, talking about life and what it is.....what is life, actually. What allows a complicated soup of molecules to spark and become life. It's not self similarity and complexity or the ability to reproduce. There are a vast number of organic chemistries which fit that description that are as far from being alive as a glass of water. Ultimately, all any living creature is just a bag of organic molecules and water. So what sparks life....no scientist has the answer to that one. So, to preclude the possibility of another form of life other than organic (no matter its chemistry) and any process that drives it, is premature. We just don't know. The only thing we can do is work with what we got and find that first. Other possibilities will come if we look for them at a later date. If they don't, then we move on.

[CraigS]

Carl;
I don't mean this to be insulting, but I find your thinking to be unconstrained to the point of being science fiction.

How could anyone possibly conceive of a way of detecting, either remotely or locally, such inorganic lifeforms ? Especially if we haven't even detected them here on lifeform central ? Would we even call them lifeforms at all ? If so, why ? If not, then their very definition automatically excludes them from the scope of detecting lifeforms !

How would you design the detection systems for MSL/Curiosity with these models in mind ?

We've gotta get real about this .. otherwise the money will disappear from the budget before we can spend it !!

Cheers

[renormalised (Carl)]

Originally Posted by CraigS

Carl;
I don't mean this to be insulting, but I find your thinking to be unconstrained to the point of being science fiction.

How could anyone possibly conceive of a way of detecting, either remotely or locally, such inorganic lifeforms ? Especially if we haven't even detected them here on lifeform central ? Would we even call them lifeforms at all ? If so, why ? If not, then their very definition automatically excludes them from the scope of detecting lifeforms !

How would you design the detection systems for MSL/Curiosity with these models in mind ?

We've gotta get real about this .. otherwise the money will disappear from the budget before we can spend it !!

Cheers

Einstein once said the most important part of doing science is having an imagination. He's right....it's precisely where Relativity and many other great leaps forward came from. Where do you think String Theory originally came from. It's where most of our greatest inventions also came from. Edison said that invention was 10% inspiration and 90% perspiration....Tesla said he quoted that because he was the most unimaginative person he'd ever met. Leaps forward can come from anywhere. Even from the "everyday drudgery" of doing science...where someone takes a step back from the assembly line process of hypothesis testing and looks at a problem from a new and different angle. Not that this way of doing things doesn't create progress. It just happens far more slowly.

Being able to locate and detect such lifeforms is upto someone to come up with a way of doing so. We know about inorganic chemistry, we know about the structure of crystals, optics, EMR, etc etc. What we need to do is to put together what we already know and extrapolate on the known principles. Experiment with what we have and come up with new ideas.

This place is hardly lifeform central. Even though we don't know of any other life bearing planet, this universe is a very big place. We should and must be prepared for any eventuality, whatever way it happens to go. Even then, we'll be in for some very big surprises.

I agree, we need to concentrate on what we know to try and find out if that type of life (carbon based) exists elsewhere in our Solar System. But even if we don't find it (which I think we will, eventually), that doesn't mean to say that we're going to be the norm throughout the galaxy or the universe, even. We may just be the unlucky sods to be one of the few (or many, who knows) that only has one life bearing planet in a system. We may even be surrounded by silicon based life...we just don't know. Look at it this way...we've barely been doing science for not much longer than 400 years and rigorous science for 250 years (if you count the Industrial Revolution as being a part of it). We're still in the first day of kindergarten...we haven't even reached Grade 1 yet. We have a long way to go and very much to learn...even of the basics.

To even think we know what we're doing or have some sort of handle on things is arrogance in the extreme. People who actually know very little are usually the ones who think they know the most. It's a very bad habit that a lot of scientists have gotten themselves into. It's a bad habit this human species as whole has gotten itself into.

Oh, you speak of lifeforms that we haven't even detected yet on Earth that are like anything I have mentioned.

Ever heard of viruses. Prions??. They are carbon based, for the most part, but they most certainly don't act in a way you'd call life in any obvious sense. Many scientists don't even consider them as being living organisms.

What do we really understand of them...less than you might think.

[CraigS]

Originally Posted by renormalised

I agree, we need to concentrate on what we know to try and find out if that type of life (carbon based) exists elsewhere in our Solar System. But even if we don't find it (which I think we will, eventually), that doesn't mean to say that we're going to be the norm throughout the galaxy or the universe, even.

No .. but if we don't face up to the evidence of a negative finding in a high probability HZ, we would never revise the search criteria, (the primary one being, the definition of HZ .. as well as the astronomical/geological/chemical theoretical grounds underpinning it). No progress will be made !

I call this denialism !

… If this were to happen, we'd be deceiving ourselves (scientifically) ... for who knows how long !?!

Originally Posted by renormalised

We may just be the unlucky sods to be one of the few (or many, who knows) that only has one life bearing planet in a system.

This fear of feeling 'unlucky' is an irrational barrier to progression as a species. I see it as being more important for humans to overcome this, than the discovery of hypothetical exo-life forms. It could be argued that this fear is the basis for 'conjuring up' in their 'existence', in the first place!

Frankly, I presently don't care whether they 'exist', or not !

Originally Posted by renormalised

We may even be surrounded by silicon based life...we just don't know. Look at it this way...we've barely been doing science for not much longer than 400 years and rigorous science for 250 years (if you count the Industrial Revolution as being a part of it). We're still in the first day of kindergarten...we haven't even reached Grade 1 yet. We have a long way to go and very much to learn...even of the basics.

Your commentary on this thread reminds me of the question:

"How long is the coastline of England ?" …

The answer is of course, "Infinite" … why ? .. because it is a fractal pattern ...

Cheers

[supernova1965 (Warren)]

Apathy is the biggest killer of scientific progress when people don't care one way or the other. If they didn't care there would be no debate so I don't believe it when lack of care is stated.