posted
Time and again - most recently while seeing the video about Proxima Centauri b at the planetarium - I have been puzzled when scientists talked about how water is imperative to life, and implied that planets in the habitable zone of their star are especially interesting not only because we could potentially live there, but also because alien beings - if at all - would exist on such a planet.
It always seemed to me that our definition of life must be too narrow to reasonably demand alien races had to meet it. Why do so many people (seem to) think there can be no life but life as we know it? Even Formics and Pequeninos were "terrestrial extraterrestrials", unlikely similar to creatures on earth... For all I know, aliens might be gasiform, or beings of energy, living on stars, or made of some element entirely unbeknownst to us. Why is the common expectation so artificially limited?
Posts: 366 | Registered: May 2016
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posted
scientists don't think there can't be no life as we know it, they just are focusing their attention on the particular elements of organic chemistry that are MOST LIKELY to produce life, simply because it is chemically capable of producing sufficiently complex, mobile, and stable bonds and protien-like things, stuff that can develop chemically that would allow life to develop.
the core chemical nature of other possible life-generating substances does not appear to harbor the same objective capacity to create stuff that we could recognize as life. given all that we know. arsenic, ammonia, etc, there's other possibilities, but water may be the optimal life production material, or the only material that complex life can use as a base ingredient or whatever. it's the universal solvent.
there's also the whole part where the only sort of life we have any sort of guarantee is possible is our own planet's life, because we exist and we can observe our own biomechanical functions in great detail.
it's like saying 'okay you could technically make a argon-based superprocessor maybe in ways we don't understand yet but silicon seems just objectively better at the base mechanical functions of creating processors'
Posts: 15421 | Registered: Aug 2005
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I agree with Sam. It's not that scientists think that water-based life is the only life possible, it's just that it's the only concrete example we have. It's easier to search for an example of something you've already observed, rather than an example of something you've only speculated about.
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quote:Originally posted by Samprimary: scientists don't think there can't be no life as we know it, they just are focusing their attention on the particular elements of organic chemistry that are MOST LIKELY to produce life. ... there's also the whole part where the only sort of life we have any sort of guarantee is possible is our own planet's life, because we exist and we can observe our own biomechanical functions in great detail.
That first part does make a lot of sense - especially linked to the last part. But it is only most likely as far as we know... And in an infinite universe, deriving likelihood from that is really a guessing game, neh?
quote:Originally posted by Sean Monahan: it's just that it's the only concrete example we have. It's easier to search for an example of something you've already observed, rather than an example of something you've only speculated about.
And this, of course, is true. I just wish people would phrase it that way.
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posted
For life as we know it to exist, that is life based on chemistry, then chemical reactions must be able to occur. These reactions need to be stable, but dynamic, and there are only a limited range of pressures, heat, and radiation variables where such reactions can occur.
Too energetic and the large molecules will not be able to last long enough, too cold and the chemical reactions to create those large molecules won't be able to occur.
Chemistry is universal, according to all modern theories used in the sciences. Life, which moves and thinks, can not spontaneously emerge from a pile of lead. Nor can it form from a bag of hydrogen.
Carbon and Oxygen are special chemicals that have the right electron shells to create the molecules that can build and grow and become life, if they are neither frozen into a solid, or energized into life.
Chemistry of that type only occurs in planets in that "Goldilocks" range.
Posts: 1941 | Registered: Feb 2003
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quote:Originally posted by PanaceaSanans: But it is only most likely as far as we know... And in an infinite universe, deriving likelihood from that is really a guessing game, neh?
when it comes right down to it, the time and resources we have to spend on efforts to find extraterrestrial life are finite and have strict physical limitations and it is a paramount sort of rationality in that we would want to use our present knowledge to triage what attempts at finding it are made and where we would prioritize our searching.
the scientific focus on goldilocks zone water-bearing worlds serves multiple rational purposes:
- given the chemical properties of water, water-based life has a potential for life we don't see readily possible with so many other types of chemical environments. this is just a matter of the chemical properties of water.
- searching for 'life as we know it' increases the likelihood that we could recognize it as life, further amplifying the rational practicality of focusing on liquid water worlds. there may be plenty of types of life that would be difficult to discern or test for, like, say, life originating in the complex chemical processes deep within the unimaginable depths of gas giants. or some bizarre fluid magma life in the strange superpressurized environments of planetary mantles. or whatever. bit more difficult to look for, to say the least.
- lastly, if we're searching in this small teensy little part of the galaxy, it makes even more sense to look for life kind of like us, as a planet in the region has this sort of life and if there is any sort of extrasolar cause for that then you could hypothesize a greater than average chance of there being additionally life-fertilized worlds near it
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