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Aliens are found! Well . . . Almost.

SLD said:
Biosignatures to be more precise. Too cool. But on a super earth orbiting a red dwarf so unlikely to be a signature of intelligent life.
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Do we really have such a firm grip on all the prerequisites for intelligent life, that we can rule it out from such a data sample?
Or could there be sets of conditions that could spawn intelligent life but are so dissimilar to earth’s conditions that we would rule them out?
 
A link without a sign up hassle.

www.nytimes.com

Astronomers Detect a Possible Signature of Life on a Distant Planet

Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable.
www.nytimes.com www.nytimes.com

Now a team of researchers is offering what it contends is the strongest indication yet of extraterrestrial life, not in our solar system but on a massive planet, known as K2-18b, that orbits a star 120 light-years from Earth. A repeated analysis of the exoplanet’s atmosphere suggests an abundance of a molecule that on Earth has only one known source: living organisms such as marine algae.

“It is in no one’s interest to claim prematurely that we have detected life,” said Nikku Madhusudhan, an astronomer at the University of Cambridge and an author of the new study, at a news conference on Tuesday. Still, he said, the best explanation for his group’s observations is that K2-18b is covered with a warm ocean, brimming with life.
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Sounds like a reasonable deduction based on what we do know.

It says nothing about the kind of life. Could be a plane of fungus or slime.
 
I agree that we don’t see recognizable signs of intelligent life or of conditions that would spawn it, by our understanding.
But I remain mindful that saying things are impossible is an impossible position to confirm. Was it Clarke?
Yes it was:

“First Law: If a distinguished but elderly scientist states something is possible, it's almost certainly true. Conversely, if they claim something is impossible, they are probably wrong.

I revert to that axiom when things are beyond my grasp (IOW, a lot).
 
I talked about this in THE Evolution Thread, but this deserves its own thread.
 
A year or two ago they found dimethyl sulfide signature but the signal was too weak to be confirmed. Produced only by life. A new study found not only the dms signature but also dimethyl disulfide, another life-only product and the signals are thousands of times stronger than earth concentration. Confirmed to three-sigma, need five-sigma.
 
SLD said:
www.nytimes.com

Astronomers Detect a Possible Signature of Life on a Distant Planet

Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable.
www.nytimes.com www.nytimes.com

Biosignatures to be more precise. Too cool. But on a super earth orbiting a red dwarf so unlikely to be a signature of intelligent life.
Click to expand...
The biosignature is three sigma, which is better than I think it was when they noticed it previously, but it still isn't the "We've got it!" level, as, if I'm not mistaken, there are other molecules that hang around the same spectral range.

And of course, while these signatures can indicate the potential for life, that is all it does at best.
 
Jimmy Higgins said:
SLD said:
www.nytimes.com

Astronomers Detect a Possible Signature of Life on a Distant Planet

Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable.
www.nytimes.com www.nytimes.com

Biosignatures to be more precise. Too cool. But on a super earth orbiting a red dwarf so unlikely to be a signature of intelligent life.
Click to expand...
The biosignature is three sigma, which is better than I think it was when they noticed it previously, but it still isn't the "We've got it!" level, as, if I'm not mistaken, there are other molecules that hang around the same spectral range.

And of course, while these signatures can indicate the potential for life, that is all it does at best.
Click to expand...

Right, they need 16-24 more hours of scope time to try for five-sigma. The point is there is no known way to produce these signatures except through life, though of course there could be such ways we do not know about.
 
Cambridge said an ocean world “teeming with life” is the best fit for the data they have.
 
Cue some fundamentalist idiot chiming in to claim it proves god exists in 3... 2... 1...
 
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On a related note, Curiosity rover finds best evidence yet for ancient life on Mars, and even what might have wiped it out if it has been wiped out.
 
pood said:
Produced only by life.
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Possibly.

The very name of the field of "organic chemistry" stems from vitalism - the firm and widespread belief that certain compounds could only be produced by life. A belief that was debunked by the 1828 synthesis of Urea from Ammonium Cyanate by Friedrich Wöhler.

Like "pornography", there's literally no solid definition of "life". We know it when we see it. All of our attempts at a definition either exclude something we are certain is alive; Or include something we are certain is not.

DMS has been detected on comets, which we are pretty confident do not harbour life. Maybe life does exist on comets; Or maybe DMS is not a definitive marker of life.

Vitalism was only disproven two centuries ago, so it is unsurprising that it is still being used as a foundation for all kinds of "scientific" endeavour.

I would be shocked if life were not commonplace on planets or moons which have liquid water; However I am highly skeptical of the idea that the detection of DMS is an adequate proof that a given exoplanet hosts life.
 
bilby said:
pood said:
Produced only by life.
Click to expand...
Possibly.

The very name of the field of "organic chemistry" stems from vitalism - the firm and widespread belief that certain compounds could only be produced by life. A belief that was debunked by the 1828 synthesis of Urea from Ammonium Cyanate by Friedrich Wöhler.

Like "pornography", there's literally no solid definition of "life". We know it when we see it. All of our attempts at a definition either exclude something we are certain is alive; Or include something we are certain is not.

DMS has been detected on comets, which we are pretty confident do not harbour life. Maybe life does exist on comets; Or maybe DMS is not a definitive marker of life.

Vitalism was only disproven two centuries ago, so it is unsurprising that it is still being used as a foundation for all kinds of "scientific" endeavour.

I would be shocked if life were not commonplace on planets or moons which have liquid water; However I am highly skeptical of the idea that the detection of DMS is an adequate proof that a given exoplanet hosts life.
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Quite right. Even if they verify DMS, they would then have to demonstrate it can’t be produced abiotically. The comet thing challenges that.
 
However, the DMS by itself has to be considered in a wider context. There appears to be a planet-wide ocean (of water? unclear), methane — related to life but also non-life — hydrogen, associated with life, and it appears to be in the habitable zone of its star.
 
There is also, possibly, the issue of what appears to be the huge abundance of DMS and dimethyl disulfide. It might that such a huge abundance is a strong indicator of “teeming” life, as cambridge put it, but I don’t know. Maybe someone else can elaborate on that.
 
pood said:
However, the DMS by itself has to be considered in a wider context. There appears to be a planet-wide ocean (of water? unclear), methane — related to life but also non-life — hydrogen, associated with life, and it appears to be in the habitable zone of its star.
Click to expand...
Hydrogen is literally everywhere. If there's matter in a place (even in intergalactic space, where atoms are widely separated and rarely meet), they are going to be mostly hydrogen atoms.

Methane and Ammonia are also ubiquitous, for the same reason - if there's carbon or nitrogen, if probably has hydrogen stuck to it (see above).

Water is the same deal - if there's an oxygen atom, it's likely to wind up as a water molecule because of all the bloody hydrogen that's worse than sand at the beach, and sticks to bloody everything.

Liquid water though, is fairly rare. And it's an excellent solvent and reaction medium for all kinds of stuff. If life really is just "complex chemistry", then it's reasonable to assume that liquid water is both a requirement for it, and a strong indicator of its likely presence.

I find it very difficult to envisage a planet sized object with permanently liquid water on its surface that does not develop life. With the surface area of a planet, the variety of trace elements, the plethora of energy gradients, and the statistical effectiveness of selection, it's hard to see how a planet with an ocean could fail to develop life.

Our sole experimental model did so very rapidly once it cooled sufficiently for oceans to form. Our best estimate suggests it took a mere three hundred million years; But the error bars on the formation of the first ocean, and on the emergence of the first life, overlap. So it could have taken even less time than that.

I would bet my boots that any planet (or moon) that has had liquid water oceans for more than a billion years will have life on it. The underlying chemistry is just not that complex - all the vast complexity and variety of life is down to subsequent selection and evolution, which once life gets going, is an incredibly powerful force for increasing diversity.
 
I think the indication here is that this planet is a water world, entirely covered by an ocean of water. But that is unclear from what I have read. Not sure what else the ocean could be made of. But, as mentioned, if it is water, we should infer an extraterrestrial Noah now riding an ark with two kinds of every six-eyed, tentacled alien.
 
pood said:
I think the indication here is that this planet is a water world, entirely covered by an ocean of water. But that is unclear from what I have read. Not sure what else the ocean could be made of. But, as mentioned, if it is water, we should infer an extraterrestrial Noah now riding an ark with two kinds of every six-eyed, tentacled alien.
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Brave of you to assume that two of every animal would be sufficient; Noah will be pretty embarrased if it comes time to repopulate the planet and it turns out that most of the animal species kinds have three genders...
 
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