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Earth May Harbor a Shadow Biosphere of Alien Life
An anonymous reader sends us to Cosmos Magazine for a speculative article arguing that a 'shadow biosphere' may exist on Earth, unrelated to life as we know it. If such non-carbon-based life were found here at home, it would alter the odds for how common life is elsewhere in the universe, astrobiologists say. "The tools and experiments researchers use to look for new forms of life — such as those on missions to Mars — would not detect biochemistries different from our own, making it easy for scientists to miss alien life, even if [it] was under their noses. ... Scientists are looking in places where life isn't expected — for example, in areas of extreme heat, cold, salt, radiation, dryness, or contaminated streams and rivers. [One researcher] is particularly interested in places that are heavily contaminated with arsenic, which, he suggests, might support forms of life that use arsenic the way life as we know it uses phosphorus."
You both have a point. The question is, where do you draw the line at what is life? Rocks may not have DNA or intelligence, but they do form, change, multiply and there's a recognisable process for destroying them. In a sense, rocks are a lot like the most basic forms of life that ever formed.
Let's be a little more serious now. Rocks around here probably won't ever advance beyond mimicking some very shaky comparisons to the most basic forms of life. But that doesn't stop us wondering if we're just seeing it on too small a scale to make that judgment. Perhaps it's safer to treat rocks as a failed attempt at life, one that happens too slowly to ever get beyond basic chemical reactions and simple molecular structures.
If it weren't for carbon-based life, who knows?
http://www.newscientist.com/article/mg19826533.600-early-life-could-have-relied-on-arsenic-dna.html tried looking up some examples of non carbon based life on earth that I'd heard of but couldn't find any however the ecology of undersea volcanic vents pretty much threw most ideas about heat tolerance and toxins being a problem out of the window.
Build a Man a Fire, and He'll Be Warm for a Day. Set a Man on Fire, and He'll Be Warm for the Rest of His Life.
You both have a point. The question is, where do you draw the line at what is life? Rocks may not have DNA or intelligence, but they do form, change, multiply and there's a recognisable process for destroying them.
Rocks do not have gaseous exchange (breathing) nor reproduce (cracking a rock to make two is _not_ reprodction). However, there is no definition of life that fire cannot meet, which the mule can. In other words, any non-contrived definition of life that includes the mule must also include fire. Here is a very basic explanation: http://simple.wikipedia.org/wiki/Life
It is dangerous to be right when the government is wrong.
You can form chains or rings of around 6 sulphurs (with oxygen), but carbon can be found in chains of 30+ atoms and in multiple ring systems.
It's very difficult to grasp how large the isomer spaces are - and how quickly they grow, but a recent guestimate I made was that if a program (molgen) can enumerate all possible C10H16 molecules in 2 seconds, and all C13H22 in 2 minutes, then it would take 2 days for C18H36 and 1 billion years for C36H72...
Also, there are 25,000 C10s and 9 million C15s. So the sheer number of possible carbon compounds argues that carbon is the only likely candidate.