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Evidence of life on Mars - how likely? Watch

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    (Original post by Kittyboy)
    Forget physics for a second, and focus on chemistry as I did. It's remarkably similar to the other dude bringing in solvents all of a sudden. I wish people would stop going off at tangents :/

    How can they possibly know that another type of element won't be able to take a similar role to carbon? You talk about carbon's complexity, but is that really such a big deal? Other elements might be a bit less complex, but that doesn't mean that they cannot support life, surely?
    Chemistry and physics are not discrete subjects. When you get to an advanced level of study you discover that there is quite a lot of overlap between the two subjects, especially past A-Level.

    The reasons that the other elements cannot sustain life on earth and in the universe in general are too complicated to go into here
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    (Original post by Plagioclase)
    They're inferior solvents but metabolic pathways using them as solvents have been predicted. Ammonia being flammable in oxygen is irrelevant if anaerobic metabolic pathways are used (i.e. most metabolic pathways) and obviously methane is even more exotic but it's still being studied seriously by exobiologists, that's the whole reason behind the NASA investigations into life on the Jovian and Saturnian moons, e.g. Titan.
    Fair enough but anaerobic metabolic pathways are energetically inferior to aerobic pathways which I think is true across all of earths life. I'm not saying that life completely based off anaerobic biochemistry is impossible but could it form complex, intelligent multi-cellular beings?
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    (Original post by Kittyboy)
    Forget physics for a second, and focus on chemistry as I did. It's remarkably similar to the other dude bringing in solvents all of a sudden. I wish people would stop going off at tangents :/

    How can they possibly know that another type of element won't be able to take a similar role to carbon? You talk about carbon's complexity, but is that really such a big deal? Other elements might be a bit less complex, but that doesn't mean that they cannot support life, surely?
    Yes, carbon's complexity is a massive deal. Life is incredibly complicated and this is all enabled by the fact that carbon-based molecules exhibit vastly more complex chemistry than any other element. People have thought about this and have theorised how life might arise around other elements and mechanisms have been suggested but they are all so vastly inferior to carbon-based chemistry that it's extremely difficult to see how they'd arise in the first place. If you've got an element that's relatively abundant in the universe and is perfect for life, it begs the question why you another element that is significantly inferior for life in every single way would become a basis for life instead. If Boron or Nitrogen or Arsenic based life, for whatever bizarre and inexplicable reason, were to ever emerge, it would be at a huge disadvantage to any carbon based life.

    To reiterate, I'm not saying that it's impossible for life to be based on an element that isn't carbon. I'm saying it's sufficiently unlikely for it not to be taken very seriously.

    We also should not forget the physics because it's very important. The fact that boron has such a low cosmic abundance completely rules it out as a basis for life. No matter how great an element is for life (and Boron isn't), if it's not there in the first place, it's not going to form life.

    (Original post by AngryRedhead)
    Fair enough but anaerobic metabolic pathways are energetically inferior to aerobic pathways which I think is true across all of earths life. I'm not saying that life completely based off anaerobic biochemistry is impossible but could it form complex, intelligent multi-cellular beings?
    Bear in mind though that if you look at the biodiversity across all forms of life on earth, by far the most diverse metabolic pathways are those expressed by single-celled, anaerobic prokaryotes. Aerobic respiration is indeed more efficient than anaerobic respiration but there are many, many more anaerobic metabolic pathways than aerobic as a result of the fact that there are many more anaerobic ecological niches than aerobic. Aerobic respiration is a relatively 'new' invention in the greater scheme of things, it is likely that most life in the universe - if there is any - would be anaerobic.

    But yes, as you correctly point out, it is unlikely that an anaerobic organism could ever become complex enough to become sentient, or anything close to that.
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    (Original post by Plagioclase)

    To reiterate, I'm not saying that it's impossible for life to be based on an element that isn't carbon. I'm saying it's sufficiently unlikely for it not to be taken very seriously.
    That took a while. So I win basically? "Unlikely" is kind of an irrelevant thing given that I believe life is a common occurrence in a potentially infinite, or just big , universe.

    I also love how you guys are taking about aerobic and anaerobic respiration. That's earth dude. I bet there's loads of other ways organisms convert energy into a compound that can easily release it
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    (Original post by Kittyboy)
    I never said that I thought solvent was the stuff in a glue tube? I think your patronising attitude is grasping for straws lol.

    By the sounds of it ammonia seems like a mighty fine solvent
    So why were you saying I was going off on a tangent for bringing up solvents then? This conversation is about the possibility of non-carbon based lifeforms and organisms are more than just what elements they are made up of. Metabolic processes in a cell wouldn't happen without a suitable solvent, that's why when people get dehydrated they die.
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    (Original post by Kittyboy)
    That took a while. So I win basically? "Unlikely" is kind of an irrelevant thing given that I believe life is a common occurrence in a potentially infinite, or just big , universe.

    I also love how you guys are taking about aerobic and anaerobic respiration. That's earth dude. I bet there's loads of other ways organisms convert energy into a compound that can easily release it
    I don't know why you're talking about "winning", saying that something is physically possible isn't the same thing as saying that something is likely. Your belief that life is a common occurrence throughout the universe is absolutely groundless. I'm pretty sure that you're just trying to wind us up now because I don't think you're that ignorant so I'm going to end this here. I'm sure there are plenty of other people who are willing to entertain you.
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    (Original post by AngryRedhead)
    So why were you saying I was going off on a tangent for bringing up solvents then?
    It's not irrelevant when other people have already introduced it into the conversation.

    (Original post by AngryRedhead)
    Metabolic processes in a cell wouldn't happen without a suitable solvent,
    I never said anything to make you reply with that. I never refuted that.
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    (Original post by Plagioclase)
    I don't know why you're talking about "winning"
    Well, I sort of won though? I just wanted to know if any other elements could take the role of carbon. The answer was yes and that yes took a while to get. I'm sorry if I come across as obnoxious. I'll just say that my winning is nothing compared to the depth of knowledge you obviously have and I wish I had.

    (Original post by Plagioclase)
    Your belief that life is a common occurrence throughout the universe is absolutely groundless. I'm pretty sure that you're just trying to wind us up now because I don't think you're that ignorant
    I'm not trying to wind anyone up. I even tried to cool the other dude down when he started to become demeaning towards me, and posted a picture of bears :/ I know you said you wouldn't reply anymore or whatever, but why is the concept that life is common groundless? NASA have found loads of earth-like planets with the correct conditions if we're considering carbon lifeforms alone. I do not think it's that big a deal, it's just we haven't found any because they may be small single-celled organisms like amoeba, and again, I refer back to the fermi paradox for more intelligent life.
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    (Original post by Kittyboy)
    Well, I sort of won though? I just wanted to know if any other elements could take the role of carbon. The answer was yes and that yes took a while to get. I'm sorry if I come across as obnoxious. I'll just say that my winning is nothing compared to the depth of knowledge you obviously have and I wish I had.
    If you count "winning" as it being physically possible to have life based on another element apart from carbon then okay, you won lol. Not entirely sure why this is a victory but well done anyway.
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    (Original post by Kittyboy)
    I'm not trying to wind anyone up. I even tried to cool the other dude down when he started to become demeaning towards me, and posted a picture of bears :/ I know you said you wouldn't reply anymore or whatever, but why is the concept that life is common groundless? NASA have found loads of earth-like planets with the correct conditions if we're considering carbon lifeforms alone. I do not think it's that big a deal, it's just we haven't found any because they may be small single-celled organisms like amoeba, and again, I refer back to the fermi paradox for more intelligent life.
    Finding habitable planets isn't the same thing as finding inhabited planets. This brings up a host of complex philosophical issues which aren't really relevant to this thread but yes, it's completely possible that the universe is full of life but it's also possible that it isn't. We simply do not know how likely it is for life to arise in the first place, nor do we have any good way of quantifying that number, nor most of the terms in the Drake Equation.
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    (Original post by Plagioclase)
    Finding habitable planets isn't the same thing as finding inhabited planets. This brings up a host of complex philosophical issues which aren't really relevant to this thread but yes, it's completely possible that the universe is full of life but it's also possible that it isn't. We simply do not know how likely it is for life to arise in the first place, nor do we have any good way of quantifying that number, nor most of the terms in the Drake Equation.
    Oh that makes perfect sense. Kind of disheartening really.
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    (Original post by Kittyboy)
    Why focus on an element that's similar to carbon? Why not one of the noble gases for instance?

    Everything we're talking about is hypothetical. Pointing out that the fermi paradox is borderline conspiracy theory-ish is itself meaningless in our debate.
    The noble gases do not form bonds. Any form of life is based eventually on chemistry, which the noble gases basically do not take part in.
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    (Original post by Kittyboy)
    It's not irrelevant when other people have already introduced it into the conversation.



    I never said anything to make you reply with that. I never refuted that.
    You said bringing up solvents was irrelevant to the topic of conversation when it's very relevant
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    (Original post by AngryRedhead)
    You said bringing up solvents was irrelevant to the topic of conversation when it's very relevant
    If you look back you just bring in solvents all of a sudden whilst also acting profoundly towards me - you even insinuate in this abrupt introduction how I don't know what solvents in this context are, despite our never discussing them. Just a weird occurrence, really weird. They were never previously discussed before that, and that's why I said it was irrelevant because we were not focused on solvents but on elements that could take carbon's place or something along those lines.

    Yeah, looking back I think you must have been in another argument at the time and got confused or something. This is all off topic unfortunately.
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    (Original post by Kittyboy)
    If you look back you just bring in solvents all of a sudden whilst also acting profoundly towards me - you even insinuate in this abrupt introduction how I don't know what solvents in this context are, despite our never discussing them. Just a weird occurrence, really weird. They were never previously discussed before that, and that's why I said it was irrelevant because we were not focused on solvents but on elements that could take carbon's place or something along those lines.

    Yeah, looking back I think you must have been in another argument at the time and got confused or something. This is all off topic unfortunately.
    Myself and Plagioclase had already explained to you why alternative biochemistries to carbon weren't really feasible which you decided to ignore for some reason. Fyi I wasn't the one posting pictures of bears.

    Solvents are just as relevant in a discussion about extra-terrestrial life as what the actual organism is composed of. I hope that everything is clearer for you now anyway
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    (Original post by anosmianAcrimony)
    The noble gases do not form bonds. Any form of life is based eventually on chemistry, which the noble gases basically do not take part in.
    I don't have a phd in chemistry surprise surprise - the noble gases were just an example and apparently there's other elements whilst not as complex are carbon can possibly assume its role.
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    (Original post by AngryRedhead)
    Myself and Plagioclase had already explained to you why alternative biochemistries to carbon weren't really feasible
    Oh you have? News to me :P
    (Original post by Plagioclase)
    To reiterate, I'm not saying that it's impossible for life to be based on an element that isn't carbon.

    (Original post by AngryRedhead)
    Fyi I wasn't the one posting pictures of bears.
    Again just what? I never said you were o.o


    (Original post by AngryRedhead)
    Solvents are just as relevant in a discussion about extra-terrestrial life as what the actual organism is composed of. I hope that everything is clearer for you now anyway
    The other dude made it clearer, quite depressingly so regrettably. I know solvents are relevant to the overall discussion, but you went from one topic we were discussing on substitutes for carbon straight to solvent, and then almost accused me of not knowing what a solvent was. Just strange is all.Anyways, thanks for the discussion, it was uh, hard to keep up in places between all the demeaning and off topic stuff .
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    (Original post by Kittyboy)
    Oh you have? News to me :P



    Again just what? I never said you were o.o


    The other dude made it clearer, quite depressingly so regrettably. I know solvents are relevant to the overall discussion, but you went from one topic we were discussing on substitutes for carbon straight to solvent, and then almost accused me of not knowing what a solvent was. Just strange is all.Anyways, thanks for the discussion, it was uh, hard to keep up in places between all the demeaning and off topic stuff .
    Yes, I explained why on the first page of this thread

    (Original post by Plagioclase)
    You will not find a respectable scientist on this planet who thinks that Boron or Nitrogen based life is remotely likely. For the reasons that AngryRedhead explained and more, it is very likely that any life that emerges in the universe will be carbon based. This is neither controversial nor is it earth-centric, it's a simple conclusion made from chemistry and physics. Carbon chemistry is vastly more complex than any other element, vastly more so than Nitrogen, and Boron-based life is even less likely because of its incredibly low cosmic abundance. Carbon, indisputably, has the most complex chemistry of any element. Scientists are not idiots, they are not saying this because it's a casual observation we've made on Earth. Secondly, I don't get which part of "the cosmic abundance of Boron is too low for it to be a base element for life" you didn't understand. We know that the abundance of Boron is low across the universe, both from theory and from observation. Again, you are the only person in the world who seems to be seriously arguing for Boron-based life or Boron-Nitrogen based life. The idea of non-carbon based life is nothing more than a scientific curiosity or a though experiment, it isn't something that astrobiologists take particularly seriously.
    Lol forget about it, you're obviously trolling at this point
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    (Original post by AngryRedhead)
    Yes, I explained why on the first page of this thread



    Lol forget about it, you're obviously trolling at this point
    The other guy later pointed out it was possible though, as delineated by his quote I put in my post quite clearly. Just because you're wrong doesn't automatically mean I'm trolling you know. You were the one being patronising if anyone is pointing fingers though lmao
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    (Original post by Kittyboy)
    The other guy later pointed out it was possible though, as delineated by his quote I put in my post quite clearly. Just because you're wrong doesn't automatically mean I'm trolling you know. You were the one being patronising if anyone is pointing fingers though lmao
    I never denied that non-carbon based life was possible, just very difficult to come by/ form. I then proceeded to give the chemical reasons why acknowledging Silicon as a possible alternative
 
 
 
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