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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.
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.
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/
If Slashdot were chemistry it would look like this:Cadaverine
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.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
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.