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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, @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!