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In the last decade, we have discovered thousands of planets outside our solar system and have learned that rocky, temperate worlds are numerous in our galaxy. The next step will involve asking even bigger questions. Could some of these planets host life? And if so, will we be able to recognize life elsewhere if we see it?
A group of leading researchers in astronomy, biology and geology has come together under NASA's Nexus for Exoplanet System Science, or NExSS, to take stock of our knowledge in the search for life on distant planets and to lay the groundwork for moving the related sciences forward.
In a set of five review papers published last week in the scientific journal Astrobiology, NExSS scientists took an inventory of the most promising signs of life, called biosignatures. The paper authors include four scientists from NASA's Jet Propulsion Laboratory in Pasadena, California. They considered how to interpret the presence of biosignatures, should we detect them on distant worlds. A primary concern is ensuring the science is strong enough to distinguish a living world from a barren planet masquerading as one.
https://www.jpl.nasa.gov/news/news.php?feature=7171
[Abstract]: Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life
[Also Covered By]: PHYS.ORG
(Score: 2) by frojack on Tuesday June 26 2018, @07:13PM (5 children)
That this story and the Jupiter The Van Gogh [soylentnews.org] one appear on the same page.
We could literally be staring at life in those Jupiter pictures and not have a single clue it was there. That atmosphere could be teaming with organisms, living in the swirls, or maybe generating them, and we would be clueless until they decided radio might be fun to play with.
We barely acknowledge life that isn't cellular in organization.
We simply ignore deeply subterranean possibilities. Except perhaps The Horta [startrek.com]
If it doesn't radiate or consume light, heat, or radio waves, we are blind to it.
No, you are mistaken. I've always had this sig.
(Score: 2) by takyon on Tuesday June 26 2018, @07:51PM
We can't detect subterranean life locked away on an exoplanet. We can't even do it in our own solar system yet. Pluto and so many other objects [wikipedia.org] could contain microbes inside of an underground ocean.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by suburbanitemediocrity on Tuesday June 26 2018, @09:00PM
The whole planet could be a sentient being.
https://en.wikipedia.org/wiki/Sentience#Sentience_quotient [wikipedia.org]
(Score: 4, Interesting) by bzipitidoo on Tuesday June 26 2018, @11:26PM (2 children)
Been working on this problem with just Mars, for over a century, starting with the wild and fanciful notions that Mars may have artificial canals built by intelligent Martians. There simply wasn't much information to work with. Now there's a lot more info, and the suppositions have changed radically, but there's still a lot of exploring and testing ahead. May be searching for centuries, maybe millennia, before we can feel pretty sure we've looked under every stone and ruled out every possibility imaginable. I think the leading idea now is that Mars could have had water oceans and microbial life that died out over a billion years ago as the oceans dried up. If there was microbial life, did it come from Earth or was there abiogenesis on Mars?
We still have much to learn about life on Earth. It was only in 1990 that the archaea were recognized as best represented in their own domain and not as a kingdom of bacteria. Today, they're still debating how best to classify organisms, and frequently proposing new schemes.
A means of doing universal computation, plus some sort of memory, stability, repeatability, and material, energy, and space to grow, may be all that's needed for life. It's stunningly easy to reach universal computation. Need any one of many simple processes. Of the basic logic operations, NOT, AND, and OR are not enough by themselves, but NAND and NOR are enough. Conway's Game of Life, and many other cellular automata, support universal computation. However, I'm guessing environments congenial to life in any form are relatively rare, that long term stability is not a trivial requirement, and that Earth is the only place with life in our solar system.
Heck, could it be possible for life to evolve on stars? We suppose that fusion and the intense heat is much too destructive to support any organization or preservation of information in a useful form, but perhaps we are wrong about that.
(Score: 2) by frojack on Tuesday June 26 2018, @11:59PM (1 child)
I have no idea of what is meant by "universal computation", but whatever it is I'm pretty sure you don't need it to meet the definition of life exhibited in countless forms right here on earth.
To assume you need concepts of AND and OR and NAND in life forms we haven't even found evidence for is kind of crazy. The whole point here is that mankind has to be prepared to find forms of life that don't meet our current definitions, may not conform to our most inclusive concepts, and are likely to be unrecognizable by those of us with fixed definitions and criteria in mind.
No, you are mistaken. I've always had this sig.
(Score: 2) by bzipitidoo on Wednesday June 27 2018, @01:47AM
Ah, no. Sorry, "universal computation" is a foundational idea of Computer Science, its proofs dating back to the 1930s. A universal computer is capable (in principle, if pesky little details like limited time and limited memory and capacity are ignored) of performing any computation that can be performed. There are extremely simple computation mechanics and systems that are not universal. For example, can't build a universal computer out of AND gates only, they aren't capable enough. But it is stunningly easy to achieve universality. NAND gates are enough. Might take millions of NAND gates, but if connected properly they can do any computation that can be done.
The question was, is there such a thing as more and less powerful computing models, and the answer is "no". That's what is meant by universality. A computer built from only NAND gates could do it all, is "universal". Beyond "not universal" and "universal", there is no such thing as different, separate classes of problems, or a computer that can compute answers to one set of problems but is incapable of computing answers to the other. For instance, in math, if a computer can do any one of addition, multiplication, exponentiation, logarithms, roots, trig, factoring, and so on, it can do them all. Computers do not have different capabilities that way.
Further, they differ in speed only by constant factors. A fast universal computer is only going to be 2 or 1000 or whatever constant faster than a slow universal computer.
If life is basically computation, and with universal computation so easily achieved, then life of at least the microbial sort might be very common in the universe. But I suspect it takes more than that. There could well be as yet undiscovered, unelucidated principles and requirements. The discipline of Computer Science is itself relatively young, and for centuries wasn't recognized as something more than just math, just another area of math like geometry and algebra. Perhaps quantum computing will someday be recognized as something that can be and should be studied separately from CS, and it should be called "quanting", or "uncertainematics" or "superpositioneering". Should be fun!