How The JWST Could Detect Signs of Life on Exoplanets (universetoday.com) 25
Universe Today reports:
The best hope for finding life on another world isn't listening for coded messages or traveling to distant stars, it's detecting the chemical signs of life in exoplanet atmospheres. This long hoped-for achievement is often thought to be beyond our current observatories, but a new study argues that the James Webb Space Telescope (JWST) could pull it off.
Most of the exoplanets we've discovered so far have been found by the transit method. This is where a planet passes in front of its star from our point of view. Even though we can't observe the planet directly, we can see the star's brightness dip by a fraction of a percent. As we watch stars over time, we can find a regular pattern of brightness dips, indicating the presence of a planet. The star dips in brightness because the planet blocks some of the starlight. But if the planet also has an atmosphere, there is a small amount of light that will pass through the atmosphere before reaching us. Depending on the chemical composition of the atmosphere, certain wavelengths will be absorbed, forming absorption spectra within the spectra of the starlight.
We have long been able to identify atoms and molecules by their absorption and emission spectra, so in principle, we can determine a planet's atmospheric composition with the transit method... We have done this with a few exoplanets, such as detecting the presence of water and organic compounds, but these were done for large gas planets with thick atmospheres. We haven't been able to do this with rocky Earth-like worlds. Our telescopes just aren't sensitive enough for that.
But this new study shows that the JWST could detect certain chemical biosignatures depending on their abundance in the atmosphere.
Long-time Slashdot reader Baron_Yam writes that "The signature I like to imagine detecting is actually industrial pollution. Chemicals that aren't created by any known geological process and indicate not just life, but life smart enough to have advanced technology (but stupid enough to pollute their own air supply)."
Most of the exoplanets we've discovered so far have been found by the transit method. This is where a planet passes in front of its star from our point of view. Even though we can't observe the planet directly, we can see the star's brightness dip by a fraction of a percent. As we watch stars over time, we can find a regular pattern of brightness dips, indicating the presence of a planet. The star dips in brightness because the planet blocks some of the starlight. But if the planet also has an atmosphere, there is a small amount of light that will pass through the atmosphere before reaching us. Depending on the chemical composition of the atmosphere, certain wavelengths will be absorbed, forming absorption spectra within the spectra of the starlight.
We have long been able to identify atoms and molecules by their absorption and emission spectra, so in principle, we can determine a planet's atmospheric composition with the transit method... We have done this with a few exoplanets, such as detecting the presence of water and organic compounds, but these were done for large gas planets with thick atmospheres. We haven't been able to do this with rocky Earth-like worlds. Our telescopes just aren't sensitive enough for that.
But this new study shows that the JWST could detect certain chemical biosignatures depending on their abundance in the atmosphere.
Long-time Slashdot reader Baron_Yam writes that "The signature I like to imagine detecting is actually industrial pollution. Chemicals that aren't created by any known geological process and indicate not just life, but life smart enough to have advanced technology (but stupid enough to pollute their own air supply)."
Oxygen Atmosphere (Score:4, Interesting)
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There are some researchers who think it is possible significant amounts of oxygen might have been created on early Earth by geological methods - apparently oxygen is released when quartz is crushed, and things like earthquakes would have liberated it.
I assume photosynthesis is significantly better at the job, but (if I recall correctly) there are some anti-oxidant functions that are so widespread in terrestrial life that they might predate the Great Oxidation Event, indicating there was enough oxygen around
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apparently oxygen is released when quartz is crushed, and things like earthquakes would have liberated it.
Or large meteor impacts.
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There will be no conclusive finding of life on other worlds until we get an actual sample into
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Carbon does look like the best base though, due to it forming polymers so well, and liquid water is such a great solvent that they must be in the mix too somehow.
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There's also the ubiquity of those elements to consider. Not only are they effective at complex chemistry... they're everywhere in relative abundance.
Stupid enough to still use fossil fuels (Score:3, Insightful)
This is basically worthless for detecting any civilization, except for one that looks almost exactly like our own at roughly the same point in our history. But the thing is, we are at a rare inflection point in our development. Either we will clean up our act and our air, or we run out of time and self-destruct instead.
The article's proposed method of detecting industrial pollution in an exoplanetary atmosphere would be more likely to detect an extinct civilization than an active one. If a civilization is able to make it a couple hundred years past where we are technologically, they will likely have fusion figured out and be able to detoxify their atmosphere, and so we won't be able to detect them for long. On the other hand, if they run out of time and die out, their pollution will linger for much longer, like the stench of a rotting corpse on a planetary scale.
The article doesn't comment on it, but I wonder if the JWST would be able to detect the signature of a nuclear armageddon?
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The insight here is that should a significantly more advanced civilization exist within our galaxy, we won't be able to see them, but they will be able to see us. Will they want to help us along, take our shit, or just be completely indifferent to us?
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I suspect anybody who could see us will not be visiting because we've got nothing they would want.
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They can travel at the speed of light, easily.
The earth is 4 billion years old. Technological society for about 200. Within about 100 more years computers will take over. Computers are software. So they can travel as signals.
Imagine if we detected a signal far away. We would, of course, decode it, and if it was a program run it. Good bye earth.
More likely, intelligent life is extremely rare. But basic algae is probably not uncommon, it was the only thing for most of earth's existence to date.
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How does an alien software program run on our hardware? Who is going to emulate alien hardware and how?
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My experience with the kind of people you just replied to is that they cannot be reasoned with... they have their 'really clever idea' and they're so attached to it they won't let it go for anything.
If there was ever a response it would almost inevitably be, "The software aliens are superintelligent, you don't know what they could figure out".
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Um, obviously it is not going to come packaged with an idiot installer for the latest version of Windows. It will require decoding, but be designed to be decoded, and so much, much easier than, say, Cuniform. E.g.
2@3#5 3@6#9
Pretty obvious @ is + and # is =.
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Lets send some pings and see what happens (Score:2)
This is why I am comfortable with the idea of our civilization sending some beamed radio signal "pings" to candidate systems.
Doubt they can visit us, but we might start to be able to signal each other.
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Why would any advanced life want anything to do with us? Imagine you are walking along a forest and you come across a pit of vipers. Do you try to pet them? Try to teach them how to get along? Take them home? No at best you film them for your YouTube channel and leave them alone. At worst .. well.
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This is one of the most common tropes in science fiction: the idea that if we meet aliens, they will be horrified by human behavior, and will react by ignoring or quarantining us. (Or perhaps they'll just wag their fingers at us and call us "Styoopid! Styoopid!", like the aliens in Plan 9 from Outer Space).
But let's think about this idea critically for a moment. If there is alien life, it presumably started the same way that human life did: by evolving, over billions of years, from a series of lower organ
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I go further than that - bilateral symmetry, a brain in a skull at the highest point on the body with the primary sense organs in it for the reduced lag time, manipulating appendages facing forward, living on land, etc. Hell, I'd bet on the forward-facing eyes and place a smaller bet on them being social herbivores, too.
There are selection pressures that made us like we are, and while I wouldn't expect an intelligent alien to be able to pass for human, finding them to be only superficially different wouldn
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Depends on how much genetic engineering they've done to themselves.
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You make a good point and analysis. But first, I was half kidding. Second, the thing is it all depends on how advanced you need to be for light speed travel. What if the aliens are one million years ahead of us. Their last murderous ancestor would have been long dead and impulse, anxiety, or aggression genes replaced and edited into docile genes. Kind of how wolves became golden retrievers except with gene editing instead selective breeding. Sure they would have a record of their ancestors being violent, bu
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It's very probable, if not certain, that we're the dumbest intelligent life in the universe.
Send beamed radio signals to candidate systems plz (Score:2)
Send beamed radio signals to candidate systems plz.
SETI - METI - active broadcasts to candidate systems [livejournal.com]