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Water Not a Good Enough Guide To Find Alien Life
An anonymous reader noted an article in Cosmos that questions the conventional wisdom of the "follow the water" strategy of seeking extraterrestrial life, saying "There's an awful lot of places where water could exist — either on the surface of the Earth, or deep within it — yet life is largely concentrated in a small sliver of this."
To find aliens, follow the latinum!
It seems to me that "follow the water" is better than seeking randomly -- if you find no water, then there can't be any life (as we know it) anyway.
Sure, if you find water, it's not a guarantee that there *is* life -- but it seems like a good way to weed out "definitely no" prospects.
Esli epei etot cumprenan, shris soa Sfaha.
So my layman's knowledge of how we gather information on the composition of a planet involves with analyzing the spectrum of light reflected by the surface of that planet from its nearby star. While molecules in the atmosphere also reflect the light and influence it, what's below the surface is based on that assumption. From there we can use other methods to determine its size and how far it is from the star it orbits to check pressure and temperatures.
... so why is this even being brought up? The article even ends with the researchers agreeing that presence of water is still our best approximation and that there should be no change in strategy.
We cannot measure the water beneath the surface (to my knowledge) so the example of the earth's composition of water is moot. If you were to take the surface of earth covered by water and then that amount of water that contains life, I think the percentage would be much higher. The microbes and small organisms that our oceans are teaming with alone would be a scientific goldmine on another planet. Of course the deep trenches of the Atlantic and Pacific will throw off your rates but we can't measure them anyway on another planet or even water in the mantle
If water isn't good enough, what is better?
My work here is dung.
You know, the earth has bacteria and fungi floating around high in the atmosphere and deep undersea -- probably even under the deep ocean, though we haven't looked there yet.
Tiny sliver... HA!
-l
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Everywhere on Earth we find water, we find life.
He's an idiot. Nothing to see here, move along.
If life is just an evolved entity composed of randomly assembled machines, as some biologists claim, then it begs the question of wether or not there might be 'life' out there that is not water based, but based on say, sand -- or silicon.
ever bother to read them? I haven't had an article accepted in over 10 years and I suspect it's because I read the link I am referring to and write an appropriate headline.
It simple states that water can exists in environments that is hostile to life as we know it.
No shit, Sherlock.
I do take issue with the idea that only 12% of the water on earth has life. AFAIK, a cup of water from any natural source in or in the ground has some sort of life in it.
The Kruger Dunning explains most post on
I don't caim having read every single one, but I think this is the dumbest news item in Slashdot in months.
Maybe intelligence is just concentrated in a small sliver of it!
It's not clear what Lineweaver is trying to say, here. Even when I took graduate astrobiology nearly 10 years ago, we were taught that you needed three things for life: raw elements (CHON, in particular), water, and an energy source. From the article, it sounds like he thinks he's had this revelatory notion just now.
Of the three ingredients, water does seem to be the hardest to find in sufficient abundance for a good likelihood of life arising anywhere. There are certain the raw materials and often energy sources available in many places, but water seems to be the missing factor in most of the solar system. So it's not a sufficient condition, it does seem like the smart thing to look for first.
(Also, his 12% figure confuses me. Is he including the entire mantle, for example? Because there isn't a lot of water there, as I recall, so you wouldn't expect to find a lot of life there. That alone would pretty easily throw the calculation in favor of his result. However, we have found life in deep rocks under the Earth, which is still pretty amazing and suggests that it's danged hardy.)
Thats very possibly true (thus the appended "as we know it".) Unfortunately saying "Here are all the reasons you might be wrong" is a lot easier than determining new approaches and going out and looking, and you've got to start somewhere.
So until new evidence points us in another direction, "follow the water" is the best direction we have.
Yeah. "Questioning the conventional wisdom" has become a worthy pursuit for its own sake. The part of questioning the conventional wisdom where you first understand the conventional wisdom, and then come up with an informed question, seems to have fallen by the wayside. But if you point out this distinction, then you're apparently attacking the idea of questioning in the first place.
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Well I am not saying it is impossible. But water has a lot of really unique chemical properties that makes randomly evolving life more likely. Being that it devolves a lot of chemicals, as well as it is sticky could come in handy in making life processes, Oh lets get rid of those pieces and glue these together while their bonds are week they stick together for a while then split. While silicon my have a lot of life giving properties for it to occur naturally/randomly you would need some medium to try to create random combination. Otherwise Sand/Silicon will be quite happy in sand like state.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
Ah, but you see, based on our sample size of ONE planet, we've determined the conditions for life on all planets.
Comparing silicon to water is wrong - silicon based life could exist, but we are not water based life, we are carbon based. Water is a solvent which we use, so where we'd need to look is where there are other liquid solvents and enough energy to allow the required reactions to happen. As already said, liquid methane might do the trick as a water substitute, but silicon wouldn't.
Nobody is saying there can't be life without water.
They're saying that since we have no idea of what it would look like, or how to look for it, there is simply no point in trying to look for it.
Tell me, how would you undertake to look for the conditions of life that we don't even have any clue as to how it works chemically? At which point, you could look at any environment and say "well, we can't rule out life there" -- which basically serves no purpose. That doesn't narrow your search in any meaningful way.
We have no ability to posit a theory, test it, or look for it when water isn't involved. At least by sticking with water within a range similar to that of Earth, we can intelligently say "well, we have life that lives in 150C, that place could as well".
There really isn't any way we can look in places that are outside what we can understand. From a science perspective, that's just simply a dead-end at present.
Lost at C:>. Found at C.
If life is just an evolved entity composed of randomly assembled machines, as some biologists claim, then it begs the question of wether or not there might be 'life' out there that is not water based, but based on say, sand -- or silicon.
That is not what "begs the question" means.
http://begthequestion.info/
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I remember a few years ago many were saying that slashdot jumped the shark, to the point where saying it jumped the shark had jumped the shark.
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Looking up some of the author's actual publications on this issue shows some very interesting details that greatly modify this picture. See: http://www.mso.anu.edu.au/~charley/papers/Jones&LineweaverProceedingsv7color.pdf.
Most remarkably he calculates that 99% of the Earth's ACTUAL liquid water contains life!!
This 12% business is the volume of the Earth where liquid water can physically exist due to its pressure-temperature phase diagram - whether or not there is actually much (or any water) there.
There are yet more limitations on this claim: it is based on the presumption that there is no life below 5 km in the Earth's crust. This is a region very slightly explored, so it can hardly be said that this claim is based on extensive direct observation. The assumption is really that the temperatures below this depth are too high life to exist (the assumed limit is 150 C). But organisms known to survive this temperature dormantly (tardigrades) are actually complex organisms (not simple extremophiles), and it was only recently that organisms were discovered that actually thrive above 121 C (the temperature of an autoclave), so the assumption that this is really the upper limit seems weak.
And the claims get even weaker. Why have we only recently discovered thermophiles above 121 C? Because there are very few accessible locations where liquid water can exist above this temp in which to observe it! Concentrated salts can raise boiling points only so far, beyond which only considerable pressure will keep it liquid. Probably the only environments we can access currently to investigate the >150 C regime are the black smoker vents on the sea floor, where emerging water hits 400 C (before rapidly cooling due to mixing).
And by this same token, the high pressure high temperature liquid water regime will be impossible for astronomers to directly observe anyway (its buried under kilometers of rock, or deep, dense atmospheres, don't ya know).
So if it is an environment where we can actually hope to OBSERVE liquid water (rather than simply postulate its existence) then yes indeed, it is almost certain to be one where life-as-we-know-it can exist.
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Well, it wasn't long ago that we were finding the first exoplanets. Now, we've found a whole lot of them.
However, damned near everything is anomalous since some of these planets are pretty extreme in terms of temperature, proximity to sun, what have you.
I think we're going to need to catalog lots more planets before we start seeing patterns that might point us to lifeforms we can't fathom yet.
Lost at C:>. Found at C.
It's unlikely enough to assemble genetic material (DNA/RNA on Earth) in a protective sheath (lipid bilayer here) in a liquid, how much more unlikely in a gas? It also means that unlike a small pool which could collect the necessary elements to create compounds in necessary quantities, these components disperse quickly in a gas. That same effect that would make life react quickly (chemically) once present would also reduce their likelyhood of appearing at all.
It's also possible extra-terrestrial intelligence could be in the form of beings made from pure energy and living in the center of stars, but it doesn't seem like the place we should start to look for them...
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I just want to reiterate what the parent said, as I'm becoming frustrated with all of the "why do we assume it can't exist if it is not like us" posts.
No one is claiming life cannot exist without water, we are only stating that life as we know it cannot. Since we have no idea what the hell we would be looking for otherwise, and since we have limited (and in the search for ET life, extremely limited) we have to determine some heuristic for our search. Since water is A) easily detected with telescopes, and B) a requirement for life as we are aware, it is so far our best means of refining our search. There may be some amazing form of X based or X requiring life out there, but since we do not know X, it is not at all helpful to acknowledge its possible existence. If, on the other hand, we happen upon X based/requiring life, we can then include X in our parameters.
Please stop assuming that this is some circa 1900AD Newtonian Physics style oversight.
Your signature contains a syntax error in most languages, but I imagine that DoWhatIWant() returns with a functioning closing parenthesis when you want one.
In looking our global ecosystem it seems to me that it is extremely fragile. There are myriad of unique characteristics of our planet that come together to support life.
Earth is just the right size to allow for a decent atmosphere.
It is just the right distance from the sun which allows for water in liquid form.
The iron core creates a magnetic field that protects us from solar radiation.
Also consider that we have just recently been able to find exoplanets, and most of what we have found are large jupiter-like planets. It is no wonder that we have not found another life-supporting planet. (yet)
One thing I would like to note is that all the great concentrations of life on this planet occur in places that are chaotic. Places where there is a fabulous mix of nutrients.
Look at the undersea steam vents, coral reefs, rain forests, and marshes. All of these are places where there is a lot of 'mixing' going on. Natures' blender, if you wish. And on a global scale, the earth itself is a great mixer. Water washes down the mountains and evaporates into the air. The moon drives tides. Currents of water and air circulate around the planet. Volcanoes and plate rifts leak minerals into the oceans and air. Fresh and saltwater mix.
Now consider the deserts of our planet. Lots of sun, but no water. And the underwater 'dead zones' devoid of sunlight, oxygen, or nutrients. These are all places where there is very little moving and mixing.
Yet some places we would never think that life could exist, it does. And it does so because of the mixing. Water is a great facilitator to that mixing, but perhaps not a requirement.
Life flourishes in chaotic environments. It is stagnation that is the bane of life. If we want to find life in the variety that matches earth, we need to find planets that are varied and wild like ours.
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Silicon doesn't have much in the way of properties that would promote life. It's a nice sci-fi treatment, from maybe the 50's, but it's not realistic chemically for exactly the reason you mentioned. Silicon readily forms a single type of crystal with itself; carbon readily forms millions upon millions of different molecules with all sorts of other elements... especially hydrogen, who has a great way of bonding/not really bonding with itself.
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